From 963f9a5c6159d985eb16b115a7d27027074827ed Mon Sep 17 00:00:00 2001 From: dhruv <856960+dhruv@users.noreply.github.com> Date: Mon, 20 Mar 2023 15:34:53 -0700 Subject: [PATCH 1/4] Squashed 'src/secp256k1/' changes from bdf39000b9..8034c67a48 8034c67a48 Add doc/ellswift.md with ElligatorSwift explanation e90aa4e62e Add ellswift testing to CI 131faedd8a Add ElligatorSwift ctime tests 198a04c058 Add tests for ElligatorSwift 9984bfe476 Add ElligatorSwift benchmarks f053da3ab7 Add ellswift module implementing ElligatorSwift 76c64be237 Add functions to test if X coordinate is valid aff948fca2 Add benchmark for key generation 5ed9314d6d Add exhaustive tests for ecmult_const_xonly b69fe88d5e Add x-only ecmult_const version for x=n/d 427bc3cdcf Merge bitcoin-core/secp256k1#1236: Update comment for secp256k1_modinv32_inv256 647f0a5cb1 Update comment for secp256k1_modinv32_inv256 5658209459 Merge bitcoin-core/secp256k1#1228: release cleanup: bump version after 0.3.0 28e63f7ea7 release cleanup: bump version after 0.3.0 git-subtree-dir: src/secp256k1 git-subtree-split: 8034c67a48dc1334bc74ee4ba239111a23d9789e --- .cirrus.yml | 16 +- CMakeLists.txt | 4 +- Makefile.am | 4 + ci/cirrus.sh | 1 + configure.ac | 17 +- doc/ellswift.md | 476 ++++++++++++++++++++++ include/secp256k1_ellswift.h | 170 ++++++++ src/bench.c | 30 +- src/ctime_tests.c | 25 ++ src/ecmult_const.h | 21 + src/ecmult_const_impl.h | 126 ++++++ src/group.h | 6 + src/group_impl.h | 25 ++ src/modinv32_impl.h | 2 +- src/modules/ellswift/Makefile.am.include | 4 + src/modules/ellswift/bench_impl.h | 100 +++++ src/modules/ellswift/main_impl.h | 492 +++++++++++++++++++++++ src/modules/ellswift/tests_impl.h | 292 ++++++++++++++ src/secp256k1.c | 4 + src/tests.c | 101 ++++- src/tests_exhaustive.c | 47 ++- 21 files changed, 1947 insertions(+), 16 deletions(-) create mode 100644 doc/ellswift.md create mode 100644 include/secp256k1_ellswift.h create mode 100644 src/modules/ellswift/Makefile.am.include create mode 100644 src/modules/ellswift/bench_impl.h create mode 100644 src/modules/ellswift/main_impl.h create mode 100644 src/modules/ellswift/tests_impl.h diff --git a/.cirrus.yml b/.cirrus.yml index 0b904a4e38c7c..b4a44c7691851 100644 --- a/.cirrus.yml +++ b/.cirrus.yml @@ -21,6 +21,7 @@ env: ECDH: no RECOVERY: no SCHNORRSIG: no + ELLSWIFT: no ### test options SECP256K1_TEST_ITERS: BENCH: yes @@ -74,12 +75,12 @@ task: << : *LINUX_CONTAINER matrix: &ENV_MATRIX - env: {WIDEMUL: int64, RECOVERY: yes} - - env: {WIDEMUL: int64, ECDH: yes, SCHNORRSIG: yes} + - env: {WIDEMUL: int64, ECDH: yes, SCHNORRSIG: yes, ELLSWIFT: yes} - env: {WIDEMUL: int128} - - env: {WIDEMUL: int128_struct} - - env: {WIDEMUL: int128, RECOVERY: yes, SCHNORRSIG: yes} + - env: {WIDEMUL: int128_struct, ELLSWIFT: yes} + - env: {WIDEMUL: int128, RECOVERY: yes, SCHNORRSIG: yes, ELLSWIFT: yes} - env: {WIDEMUL: int128, ECDH: yes, SCHNORRSIG: yes} - - env: {WIDEMUL: int128, ASM: x86_64} + - env: {WIDEMUL: int128, ASM: x86_64 , ELLSWIFT: yes} - env: { RECOVERY: yes, SCHNORRSIG: yes} - env: {CTIMETESTS: no, RECOVERY: yes, ECDH: yes, SCHNORRSIG: yes, CPPFLAGS: -DVERIFY} - env: {BUILD: distcheck, WITH_VALGRIND: no, CTIMETESTS: no, BENCH: no} @@ -154,6 +155,7 @@ task: ECDH: yes RECOVERY: yes SCHNORRSIG: yes + ELLSWIFT: yes CTIMETESTS: no << : *MERGE_BASE test_script: @@ -173,6 +175,7 @@ task: ECDH: yes RECOVERY: yes SCHNORRSIG: yes + ELLSWIFT: yes CTIMETESTS: no matrix: - env: {} @@ -193,6 +196,7 @@ task: ECDH: yes RECOVERY: yes SCHNORRSIG: yes + ELLSWIFT: yes CTIMETESTS: no << : *MERGE_BASE test_script: @@ -210,6 +214,7 @@ task: ECDH: yes RECOVERY: yes SCHNORRSIG: yes + ELLSWIFT: yes CTIMETESTS: no << : *MERGE_BASE test_script: @@ -247,6 +252,7 @@ task: RECOVERY: yes EXPERIMENTAL: yes SCHNORRSIG: yes + ELLSWIFT: yes CTIMETESTS: no # Use a MinGW-w64 host to tell ./configure we're building for Windows. # This will detect some MinGW-w64 tools but then make will need only @@ -286,6 +292,7 @@ task: ECDH: yes RECOVERY: yes SCHNORRSIG: yes + ELLSWIFT: yes CTIMETESTS: no matrix: - name: "Valgrind (memcheck)" @@ -361,6 +368,7 @@ task: ECDH: yes RECOVERY: yes SCHNORRSIG: yes + ELLSWIFT: yes << : *MERGE_BASE test_script: - ./ci/cirrus.sh diff --git a/CMakeLists.txt b/CMakeLists.txt index 5c8aad6fcc2c6..ddc6c7e6d47bf 100644 --- a/CMakeLists.txt +++ b/CMakeLists.txt @@ -10,7 +10,7 @@ endif() # The package (a.k.a. release) version is based on semantic versioning 2.0.0 of # the API. All changes in experimental modules are treated as # backwards-compatible and therefore at most increase the minor version. -project(libsecp256k1 VERSION 0.3.0 LANGUAGES C) +project(libsecp256k1 VERSION 0.3.1 LANGUAGES C) # The library version is based on libtool versioning of the ABI. The set of # rules for updating the version can be found here: @@ -18,7 +18,7 @@ project(libsecp256k1 VERSION 0.3.0 LANGUAGES C) # All changes in experimental modules are treated as if they don't affect the # interface and therefore only increase the revision. set(${PROJECT_NAME}_LIB_VERSION_CURRENT 2) -set(${PROJECT_NAME}_LIB_VERSION_REVISION 0) +set(${PROJECT_NAME}_LIB_VERSION_REVISION 1) set(${PROJECT_NAME}_LIB_VERSION_AGE 0) set(CMAKE_C_STANDARD 90) diff --git a/Makefile.am b/Makefile.am index e3fdf4da27619..2b5e99455fde2 100644 --- a/Makefile.am +++ b/Makefile.am @@ -247,3 +247,7 @@ endif if ENABLE_MODULE_SCHNORRSIG include src/modules/schnorrsig/Makefile.am.include endif + +if ENABLE_MODULE_ELLSWIFT +include src/modules/ellswift/Makefile.am.include +endif diff --git a/ci/cirrus.sh b/ci/cirrus.sh index 8495c39203fdf..0b494c5de1d27 100755 --- a/ci/cirrus.sh +++ b/ci/cirrus.sh @@ -62,6 +62,7 @@ fi --with-ecmult-window="$ECMULTWINDOW" \ --with-ecmult-gen-precision="$ECMULTGENPRECISION" \ --enable-module-ecdh="$ECDH" --enable-module-recovery="$RECOVERY" \ + --enable-module-ellswift="$ELLSWIFT" \ --enable-module-schnorrsig="$SCHNORRSIG" \ --enable-examples="$EXAMPLES" \ --enable-ctime-tests="$CTIMETESTS" \ diff --git a/configure.ac b/configure.ac index a46a0a7be35b0..acf0bab851454 100644 --- a/configure.ac +++ b/configure.ac @@ -5,8 +5,8 @@ AC_PREREQ([2.60]) # backwards-compatible and therefore at most increase the minor version. define(_PKG_VERSION_MAJOR, 0) define(_PKG_VERSION_MINOR, 3) -define(_PKG_VERSION_PATCH, 0) -define(_PKG_VERSION_IS_RELEASE, true) +define(_PKG_VERSION_PATCH, 1) +define(_PKG_VERSION_IS_RELEASE, false) # The library version is based on libtool versioning of the ABI. The set of # rules for updating the version can be found here: @@ -14,7 +14,7 @@ define(_PKG_VERSION_IS_RELEASE, true) # All changes in experimental modules are treated as if they don't affect the # interface and therefore only increase the revision. define(_LIB_VERSION_CURRENT, 2) -define(_LIB_VERSION_REVISION, 0) +define(_LIB_VERSION_REVISION, 1) define(_LIB_VERSION_AGE, 0) AC_INIT([libsecp256k1],m4_join([.], _PKG_VERSION_MAJOR, _PKG_VERSION_MINOR, _PKG_VERSION_PATCH)m4_if(_PKG_VERSION_IS_RELEASE, [true], [], [-dev]),[https://github.com/bitcoin-core/secp256k1/issues],[libsecp256k1],[https://github.com/bitcoin-core/secp256k1]) @@ -178,6 +178,11 @@ AC_ARG_ENABLE(module_schnorrsig, AS_HELP_STRING([--enable-module-schnorrsig],[enable schnorrsig module [default=yes]]), [], [SECP_SET_DEFAULT([enable_module_schnorrsig], [yes], [yes])]) +AC_ARG_ENABLE(module_ellswift, + AS_HELP_STRING([--enable-module-ellswift],[enable ElligatorSwift module (experimental)]), + [enable_module_ellswift=$enableval], + [enable_module_ellswift=no]) + AC_ARG_ENABLE(external_default_callbacks, AS_HELP_STRING([--enable-external-default-callbacks],[enable external default callback functions [default=no]]), [], [SECP_SET_DEFAULT([enable_external_default_callbacks], [no], [no])]) @@ -380,6 +385,10 @@ if test x"$enable_module_schnorrsig" = x"yes"; then enable_module_extrakeys=yes fi +if test x"$enable_module_ellswift" = x"yes"; then + AC_DEFINE(ENABLE_MODULE_ELLSWIFT, 1, [Define this symbol to enable the ElligatorSwift module]) +fi + # Test if extrakeys is set after the schnorrsig module to allow the schnorrsig # module to set enable_module_extrakeys=yes if test x"$enable_module_extrakeys" = x"yes"; then @@ -422,6 +431,7 @@ AM_CONDITIONAL([ENABLE_MODULE_ECDH], [test x"$enable_module_ecdh" = x"yes"]) AM_CONDITIONAL([ENABLE_MODULE_RECOVERY], [test x"$enable_module_recovery" = x"yes"]) AM_CONDITIONAL([ENABLE_MODULE_EXTRAKEYS], [test x"$enable_module_extrakeys" = x"yes"]) AM_CONDITIONAL([ENABLE_MODULE_SCHNORRSIG], [test x"$enable_module_schnorrsig" = x"yes"]) +AM_CONDITIONAL([ENABLE_MODULE_ELLSWIFT], [test x"$enable_module_ellswift" = x"yes"]) AM_CONDITIONAL([USE_EXTERNAL_ASM], [test x"$enable_external_asm" = x"yes"]) AM_CONDITIONAL([USE_ASM_ARM], [test x"$set_asm" = x"arm"]) AM_CONDITIONAL([BUILD_WINDOWS], [test "$build_windows" = "yes"]) @@ -443,6 +453,7 @@ echo " module ecdh = $enable_module_ecdh" echo " module recovery = $enable_module_recovery" echo " module extrakeys = $enable_module_extrakeys" echo " module schnorrsig = $enable_module_schnorrsig" +echo " module ellswift = $enable_module_ellswift" echo echo " asm = $set_asm" echo " ecmult window size = $set_ecmult_window" diff --git a/doc/ellswift.md b/doc/ellswift.md new file mode 100644 index 0000000000000..ed8336fcccc89 --- /dev/null +++ b/doc/ellswift.md @@ -0,0 +1,476 @@ +# ElligatorSwift for secp256k1 explained + +In this document we explain how the `ellswift` module implementation is related to the +construction in the +["SwiftEC: Shallue–van de Woestijne Indifferentiable Function To Elliptic Curves"](https://eprint.iacr.org/2022/759) +paper by Jorge Chávez-Saab, Francisco Rodríguez-Henríquez, and Mehdi Tibouchi. + +* [1. Introduction](#1-introduction) +* [2. The decoding function](#2-the-decoding-function) + + [2.1 Decoding for `secp256k1`](#21-decoding-for-secp256k1) +* [3. The encoding function](#3-the-encoding-function) + + [3.1 Switching to *v, w* coordinates](#31-switching-to-v-w-coordinates) + + [3.2 Avoiding computing all inverses](#32-avoiding-computing-all-inverses) + + [3.3 Finding the inverse](#33-finding-the-inverse) + + [3.4 Dealing with special cases](#34-dealing-with-special-cases) + + [3.5 Encoding for `secp256k1`](#35-encoding-for-secp256k1) +* [4. Encoding and decoding full *(x, y)* coordinates](#4-encoding-and-decoding-full-x-y-coordinates) + + [4.1 Full *(x, y)* coordinates for `secp256k1`](#41-full-x-y-coordinates-for-secp256k1) + +## 1. Introduction + +The `ellswift` module effectively introduces a new 64-byte public key format, with the property +that (uniformly random) public keys can be encoded as 64-byte arrays which are computationally +indistinguishable from uniform byte arrays. The module provides functions to convert public keys +from and to this format, as well as convenience functions for key generation and ECDH that operate +directly on ellswift-encoded keys. + +The encoding consists of the concatenation of two (32-byte big endian) encoded field elements $u$ +and $t.$ Together they encode an x-coordinate on the curve $x$, or (see further) a full point $(x, y)$ on +the curve. + +**Decoding** consists of decoding the field elements $u$ and $t$ (values above the field size $p$ +are taken modulo $p$), and then evaluating $F_u(t)$, which for every $u$ and $t$ results in a valid +x-coordinate on the curve. The functions $F_u$ will be defined in [Section 2](#2-the-decoding-function). + +**Encoding** a given $x$ coordinate is conceptually done as follows: +* Loop: + * Pick a uniformy random field element $u.$ + * Compute the set $L = F_u^{-1}(x)$ of $t$ values for which $F_u(t) = x$, which may have up to *8* elements. + * With probability $1 - \dfrac{\\#L}{8}$, restart the loop. + * Select a uniformly random $t \in L$ and return $(u, t).$ + +This is the *ElligatorSwift* algorithm, here given for just x-coordinates. An extension to full +$(x, y)$ points will be given in [Section 4](#4-encoding-and-decoding-full-x-y-coordinates). +The algorithm finds a uniformly random $(u, t)$ among (almost all) those +for which $F_u(t) = x.$ Section 3.2 in the paper proves that the number of such encodings for +almost all x-coordinates on the curve (all but at most 39) is close to two times the field size +(specifically, it lies in the range $2q \pm (22\sqrt{q} + O(1))$, where $q$ is the size of the field). + +## 2. The decoding function + +First some definitions: +* $\mathbb{F}$ is the finite field of size $q$, of characteristic 5 or more, and $q \equiv 1 \mod 3.$ + * For `secp256k1`, $q = 2^{256} - 2^{32} - 977$, which satisfies that requirement. +* Let $E$ be the elliptic curve of points $(x, y) \in \mathbb{F}^2$ for which $y^2 = x^3 + ax + b$, with $a$ and $b$ + public constants, for which $\Delta_E = -16(4a^3 + 27b^2)$ is a square, and at least one of $(-b \pm \sqrt{-3 \Delta_E} / 36)/2$ is a square. + This implies that the order of $E$ is either odd, or a multiple of *4*. + If $a=0$, this condition is always fulfilled. + * For `secp256k1`, $a=0$ and $b=7.$ +* Let the function $g(x) = x^3 + ax + b$, so the $E$ curve equation is also $y^2 = g(x).$ +* Let the function $h(x) = 3x^3 + 4a.$ +* Define $V$ as the set of solutions $(x_1, x_2, x_3, z)$ to $z^2 = g(x_1)g(x_2)g(x_3).$ +* Define $S_u$ as the set of solutions $(X, Y)$ to $X^2 + h(u)Y^2 = -g(u)$ and $Y \neq 0.$ +* $P_u$ is a function from $\mathbb{F}$ to $S_u$ that will be defined below. +* $\psi_u$ is a function from $S_u$ to $V$ that will be defined below. + +**Note**: In the paper: +* $F_u$ corresponds to $F_{0,u}$ there. +* $P_u(t)$ is called $P$ there. +* All $S_u$ sets together correspond to $S$ there. +* All $\psi_u$ functions together (operating on elements of $S$) correspond to $\psi$ there. + +Note that for $V$, the left hand side of the equation $z^2$ is square, and thus the right +hand must also be square. As multiplying non-squares results in a square in $\mathbb{F}$, +out of the three right-hand side factors an even number must be non-squares. +This implies that exactly *1* or exactly *3* out of +$\\{g(x_1), g(x_2), g(x_3)\\}$ must be square, and thus that for any $(x_1,x_2,x_3,z) \in V$, +at least one of $\\{x_1, x_2, x_3\\}$ must be a valid x-coordinate on $E.$ There is one exception +to this, namely when $z=0$, but even then one of the three values is a valid x-coordinate. + +**Define** the decoding function $F_u(t)$ as: +* Let $(x_1, x_2, x_3, z) = \psi_u(P_u(t)).$ +* Return the first element $x$ of $(x_3, x_2, x_1)$ which is a valid x-coordinate on $E$ (i.e., $g(x)$ is square). + +$P_u(t) = (X(u, t), Y(u, t))$, where: + +$$ +\begin{array}{lcl} +X(u, t) & = & \left\\{\begin{array}{ll} + \dfrac{g(u) - t^2}{2t} & a = 0 \\ + \dfrac{g(u) + h(u)(Y_0(u) + X_0(u)t)^2}{X_0(u)(1 + h(u)t^2)} & a \neq 0 +\end{array}\right. \\ +Y(u, t) & = & \left\\{\begin{array}{ll} + \dfrac{X(u, t) + t}{u \sqrt{-3}} = \dfrac{g(u) + t^2}{2tu\sqrt{-3}} & a = 0 \\ + Y_0(u) + t(X(u, t) - X_0(u)) & a \neq 0 +\end{array}\right. +\end{array} +$$ + +$P_u(t)$ is defined: +* For $a=0$, unless: + * $u = 0$ or $t = 0$ (division by zero) + * $g(u) = -t^2$ (would give $Y=0$). +* For $a \neq 0$, unless: + * $X_0(u) = 0$ or $h(u)t^2 = -1$ (division by zero) + * $Y_0(u) (1 - h(u)t^2) = 2X_0(u)t$ (would give $Y=0$). + +The functions $X_0(u)$ and $Y_0(u)$ are defined in Appendix A of the paper, and depend on various properties of $E.$ + +The function $\psi_u$ is the same for all curves: $\psi_u(X, Y) = (x_1, x_2, x_3, z)$, where: + +$$ +\begin{array}{lcl} + x_1 & = & \dfrac{X}{2Y} - \dfrac{u}{2} && \\ + x_2 & = & -\dfrac{X}{2Y} - \dfrac{u}{2} && \\ + x_3 & = & u + 4Y^2 && \\ + z & = & \dfrac{g(x_3)}{2Y}(u^2 + ux_1 + x_1^2 + a) = \dfrac{-g(u)g(x_3)}{8Y^3} +\end{array} +$$ + +### 2.1 Decoding for `secp256k1` + +Put together and specialized for $a=0$ curves, decoding $(u, t)$ to an x-coordinate is: + +**Define** $F_u(t)$ as: +* Let $X = \dfrac{u^3 + b - t^2}{2t}.$ +* Let $Y = \dfrac{X + t}{u\sqrt{-3}}.$ +* Return the first $x$ in $(u + 4Y^2, \dfrac{-X}{2Y} - \dfrac{u}{2}, \dfrac{X}{2Y} - \dfrac{u}{2})$ for which $g(x)$ is square. + +To make sure that every input decodes to a valid x-coordinate, we remap the inputs in case +$P_u$ is not defined (when $u=0$, $t=0$, or $g(u) = -t^2$): + +**Define** $F_u(t)$ as: +* Let $u'=u$ if $u \neq 0$; $1$ otherwise (guaranteeing $u' \neq 0$). +* Let $t'=t$ if $t \neq 0$; $1$ otherwise (guaranteeing $t' \neq 0$). +* Let $t''=t'$ if $g(u') \neq -t'^2$; $2t'$ otherwise (guaranteeing $t'' \neq 0$ and $g(u') \neq -t''^2$). +* Let $X = \dfrac{u'^3 + b - t''^2}{2t''}.$ +* Let $Y = \dfrac{X + t''}{u'\sqrt{-3}}.$ +* Return the first $x$ in $(u' + 4Y^2, \dfrac{-X}{2Y} - \dfrac{u'}{2}, \dfrac{X}{2Y} - \dfrac{u'}{2})$ for which $x^3 + b$ is square. + +The choices here are not strictly necessary. Just returning a fixed constant in any of the undefined cases would suffice, +but the approach here is simple enough and gives fairly uniform output even in these cases. + +**Note**: in the paper these conditions result in $\infty$ as output, due to the use of projective coordinates there. +We wish to avoid the need for callers to deal with this special case. + +This is implemented in `secp256k1_ellswift_xswiftec_frac_var` (which decodes to an x-coordinate represented as a fraction), and +in `secp256k1_ellswift_xswiftec_var` (which outputs the actual x-coordinate). + +## 3. The encoding function + +To implement $F_u^{-1}(x)$, the function to find the set of inverses $t$ for which $F_u(t) = x$, we have to reverse the process: +* Find all the $(X, Y) \in S_u$ that could have given rise to $x$, through the $x_1$, $x_2$, or $x_3$ formulas in $\psi_u.$ +* Map those $(X, Y)$ solutions to $t$ values using $P_u^{-1}(X, Y).$ +* For each of the found $t$ values, verify that $F_u(t) = x.$ +* Return the remaining $t$ values. + +The function $P_u^{-1}$, which finds $t$ given $(X, Y) \in S_u$, is significantly simpler than $P_u:$ + +$$ +P_u^{-1}(X, Y) = \left\\{\begin{array}{ll} +Yu\sqrt{-3} - X & a = 0 \\ +\dfrac{Y-Y_0(u)}{X-X_0(u)} & a \neq 0 \land X \neq X_0(u) \\ +\dfrac{-X_0(u)}{h(u)Y_0(u)} & a \neq 0 \land X = X_0(u) \land Y = Y_0(u) +\end{array}\right. +$$ + +The third step above, verifying that $F_u(t) = x$, is necessary because for the $(X, Y)$ values found through the $x_1$ and $x_2$ expressions, +it is possible that decoding through $\psi_u(X, Y)$ yields a valid $x_3$ on the curve, which would take precedence over the +$x_1$ or $x_2$ decoding. These $(X, Y)$ solutions must be rejected. + +Since we know that exactly one or exactly three out of $\\{x_1, x_2, x_3\\}$ are valid x-coordinates for any $t$, +the case where either $x_1$ or $x_2$ is valid and in addition also $x_3$ is valid must mean that all three are valid. +This means that instead of checking whether $x_3$ is on the curve, it is also possible to check whether the other one out of +$x_1$ and $x_2$ is on the curve. This is significantly simpler, as it turns out. + +Observe that $\psi_u$ guarantees that $x_1 + x_2 = -u.$ So given either $x = x_1$ or $x = x_2$, the other one of the two can be computed as +$-u - x.$ Thus, when encoding $x$ through the $x_1$ or $x_2$ expressions, one can simply check whether $g(-u-x)$ is a square, +and if so, not include the corresponding $t$ values in the returned set. As this does not need $X$, $Y$, or $t$, this condition can be determined +before those values are computed. + +It is not possible that an encoding found through the $x_1$ expression decodes to a different valid x-coordinate using $x_2$ (which would +take precedence), for the same reason: if both $x_1$ and $x_2$ decodings were valid, $x_3$ would be valid as well, and thus take +precedence over both. Because of this, the $g(-u-x)$ being square test for $x_1$ and $x_2$ is the only test necessary to guarantee the found $t$ +values round-trip back to the input $x$ correctly. This is the reason for choosing the $(x_3, x_2, x_1)$ precedence order in the decoder; +any other order requires more complicated round-trip checks in the encoder. + +### 3.1 Switching to *v, w* coordinates + +Before working out the formulas for all this, we switch to different variables for $S_u.$ Let $v = (X/Y - u)/2$, and +$w = 2Y.$ Or in the other direction, $X = w(u/2 + v)$ and $Y = w/2:$ +* $S_u'$ becomes the set of $(v, w)$ for which $w^2 (u^2 + uv + v^2 + a) = -g(u)$ and $w \neq 0.$ +* For $a=0$ curves, $P_u^{-1}$ can be stated for $(v,w)$ as $P_u^{'-1}(v, w) = w\left(\frac{\sqrt{-3}-1}{2}u - v\right).$ +* $\psi_u$ can be stated for $(v, w)$ as $\psi_u'(v, w) = (x_1, x_2, x_3, z)$, where + +$$ +\begin{array}{lcl} + x_1 & = & v \\ + x_2 & = & -u - v \\ + x_3 & = & u + w^2 \\ + z & = & \dfrac{g(x_3)}{w}(u^2 + uv + v^2 + a) = \dfrac{-g(u)g(x_3)}{w^3} +\end{array} +$$ + +We can now write the expressions for finding $(v, w)$ given $x$ explicitly, by solving each of the $\\{x_1, x_2, x_3\\}$ +expressions for $v$ or $w$, and using the $S_u'$ equation to find the other variable: +* Assuming $x = x_1$, we find $v = x$ and $w = \pm\sqrt{-g(u)/(u^2 + uv + v^2 + a)}.$ +* Assuming $x = x_2$, we find $v = -u-x$ and $w = \pm\sqrt{-g(u)/(u^2 + uv + v^2 + a)}.$ +* Assuming $x = x_3$, we find $w = \pm\sqrt{x-u}$ and $v = -u/2 \pm \sqrt{-w^2(4g(u) + w^2h(u))}/(2w^2).$ + +### 3.2 Avoiding computing all inverses + +The *ElligatorSwift* algorithm as stated in Section 1 requires the computation of $L = F_u^{-1}(x)$ (the +set of all $t$ such that $(u, t)$ decode to $x$) in full. This is unnecessary. + +Observe that the procedure of restarting with probability $(1 - \frac{\\#L}{8})$ and otherwise returning a +uniformly random element from $L$ is actually equivalent to always padding $L$ with $\bot$ values up to length 8, +picking a uniformly random element from that, restarting whenever $\bot$ is picked: + +**Define** *ElligatorSwift(x)* as: +* Loop: + * Pick a uniformly random field element $u.$ + * Compute the set $L = F_u^{-1}(x).$ + * Let $T$ be the 8-element vector consisting of the elements of $L$, plus $8 - \\#L$ times $\\{\bot\\}.$ + * Select a uniformly random $t \in T.$ + * If $t \neq \bot$, return $(u, t)$; restart loop otherwise. + +Now notice that the order of elements in $T$ does not matter, as all we do is pick a uniformly +random element in it, so we do not need to have all $\bot$ values at the end. +As we have 8 distinct formulas for finding $(v, w)$ (taking the variants due to $\pm$ into account), +we can associate every index in $T$ with exactly one of those formulas, making sure that: +* Formulas that yield no solutions (due to division by zero or non-existing square roots) or invalid solutions are made to return $\bot.$ +* For the $x_1$ and $x_2$ cases, if $g(-u-x)$ is a square, $\bot$ is returned instead (the round-trip check). +* In case multiple formulas would return the same non- $\bot$ result, all but one of those must be turned into $\bot$ to avoid biasing those. + +The last condition above only occurs with negligible probability for cryptographically-sized curves, but is interesting +to take into account as it allows exhaustive testing in small groups. See [Section 3.4](#34-dealing-with-special-cases) +for an analysis of all the negligible cases. + +If we define $T = (G_{0,u}(x), G_{1,u}(x), \ldots, G_{7,u}(x))$, with each $G_{i,u}$ matching one of the formulas, +the loop can be simplified to only compute one of the inverses instead of all of them: + +**Define** *ElligatorSwift(x)* as: +* Loop: + * Pick a uniformly random field element $u.$ + * Pick a uniformly random integer $c$ in $[0,8).$ + * Let $t = G_{c,u}(x).$ + * If $t \neq \bot$, return $(u, t)$; restart loop otherwise. + +This is implemented in `secp256k1_ellswift_xelligatorswift_var`. + +### 3.3 Finding the inverse + +To implement $G_{c,u}$, we map $c=0$ to the $x_1$ formula, $c=1$ to the $x_2$ formula, and $c=2$ and $c=3$ to the $x_3$ formula. +Those are then repeated as $c=4$ through $c=7$ for the other sign of $w$ (noting that in each formula, $w$ is a square root of some expression). +Ignoring the negligible cases, we get: + +**Define** $G_{c,u}(x)$ as: +* If $c \in \\{0, 1, 4, 5\\}$ (for $x_1$ and $x_2$ formulas): + * If $g(-u-x)$ is square, return $\bot$ (as $x_3$ would be valid and take precedence). + * If $c \in \\{0, 4\\}$ (the $x_1$ formula) let $v = x$, otherwise let $v = -u-x$ (the $x_2$ formula) + * Let $s = -g(u)/(u^2 + uv + v^2 + a)$ (using $s = w^2$ in what follows). +* Otherwise, when $c \in \\{2, 3, 6, 7\\}$ (for $x_3$ formulas): + * Let $s = x-u.$ + * Let $r = \sqrt{-s(4g(u) + sh(u))}.$ + * Let $v = (r/s - u)/2$ if $c \in \\{3, 7\\}$; $(-r/s - u)/2$ otherwise. +* Let $w = \sqrt{s}.$ +* Depending on $c:$ + * If $c \in \\{0, 1, 2, 3\\}:$ return $P_u^{'-1}(v, w).$ + * If $c \in \\{4, 5, 6, 7\\}:$ return $P_u^{'-1}(v, -w).$ + +Whenever a square root of a non-square is taken, $\bot$ is returned; for both square roots this happens with roughly +50% on random inputs. Similarly, when a division by 0 would occur, $\bot$ is returned as well; this will only happen +with negligible probability. The division in the first branch in fact cannot occur at all, $u^2 + uv + v^2 + a = 0$ +implies $g(-u-x) = g(x)$ which would mean the $g(-u-x)$ is square condition has triggered +and $\bot$ would have been returned already. + +**Note**: In the paper, the $case$ variable corresponds roughly to the $c$ above, but only takes on 4 possible values (1 to 4). +The conditional negation of $w$ at the end is done randomly, which is equivalent, but makes testing harder. We choose to +have the $G_{c,u}$ be deterministic, and capture all choices in $c.$ + +Now observe that the $c \in \\{1, 5\\}$ and $c \in \\{3, 7\\}$ conditions effectively perform the same $v \rightarrow -u-v$ +transformation. Furthermore, that transformation has no effect on $s$ in the first branch +as $u^2 + ux + x^2 + a = u^2 + u(-u-x) + (-u-x)^2 + a.$ Thus we can extract it out and move it down: + +**Define** $G_{c,u}(x)$ as: +* If $c \in \\{0, 1, 4, 5\\}:$ + * If $g(-u-x)$ is square, return $\bot.$ + * Let $s = -g(u)/(u^2 + ux + x^2 + a).$ + * Let $v = x.$ +* Otherwise, when $c \in \\{2, 3, 6, 7\\}:$ + * Let $s = x-u.$ + * Let $r = \sqrt{-s(4g(u) + sh(u))}.$ + * Let $v = (r/s - u)/2.$ +* Let $w = \sqrt{s}.$ +* Depending on $c:$ + * If $c \in \\{0, 2\\}:$ return $P_u^{'-1}(v, w).$ + * If $c \in \\{1, 3\\}:$ return $P_u^{'-1}(-u-v, w).$ + * If $c \in \\{4, 6\\}:$ return $P_u^{'-1}(v, -w).$ + * If $c \in \\{5, 7\\}:$ return $P_u^{'-1}(-u-v, -w).$ + +This shows there will always be exactly 0, 4, or 8 $t$ values for a given $(u, x)$ input. +There can be 0, 1, or 2 $(v, w)$ pairs before invoking $P_u^{'-1}$, and each results in 4 distinct $t$ values. + +### 3.4 Dealing with special cases + +As mentioned before there are a few cases to deal with which only happen in a negligibly small subset of inputs (besides division by zero). +For cryptographically sized curves, if only random inputs are going to be considered, it is unnecessary to deal with these. Still, for completeness +we analyse them here. They generally fall into two categories: cases in which the encoder would produce $t$ values that +do not decode back to $x$ (or at least cannot guarantee that they do), and cases in which the encoder might produce the same +$t$ value for multiple $c$ inputs (thereby biasing that encoding): + +* In the branch for $x_1$ and $x_2$ (where $c \in \\{0, 1, 4, 5\\}$): + * When $g(u) = 0$, we would have $s=w=Y=0$, which is not on $S_u.$ This is only possible on even-ordered curves. + Excluding this also removes the one condition under which the simplified check for $x_3$ on the curve + fails (namely when $g(x_1)=g(x_2)=0$ but $g(x_3)$ is not square). + This does exclude some valid encodings: when both $g(u)=0$ and $u^2+ux+x^2+a=0$ (also implying $g(x)=0$), + the $S_u'$ equation degenerates to $0 = 0$, and many valid $t$ values may exist. Yet, these cannot be targetted uniformly by the + encoder anyway as there will generally be more than 8. + * When $g(x) = 0$, the same $t$ would be produced as in the $x_3$ branch (where $c \in \\{2, 3, 6, 7\\}$) which we give precedence + as it can deal with $g(u)=0$. + This is again only possible on even-ordered curves. +* In the branch for $x_3$ (where $c \in \\{2, 3, 6, 7\\}$): + * When $u = -u-v$ and $c \in \\{3, 7\\}$, the same $t$ would be returned as in the $c \in \\{2, 6\\}$ cases. + It is equivalent to checking whether the square root is zero. + This cannot occur in the $x_1$ / $x_2$ branch, as it would trigger the $g(-u-x)$ is square condition. + A similar concern for $w = -w$ does not exist, as $w=0$ is already impossible in both branches: in the first + it requires $g(u)=0$ which is already outlawed; in the second it would trigger division by zero. +* In the implementation of $P_u^{'-1}$, special cases can occur: + * For $a=0$ curves, $u=0$ and $t=0$ need to be avoided as they would trigger division by zero in the decoder. + The latter is only possible when $g(u)=0$ and can thus only occur on even-ordered curves. + * For $a \neq 0$ curves, $h(u)t^2 = -1$ needs to be avoided as it would trigger division by zero in the decoder. + * Also for $a \neq 0$ curves, if $w(u/2 + v) = X_0(u)$ but $w/2 \neq Y_0(u)$, no $t$ exists. + +**Define** a version of $G_{c,u}(x)$ which deals with all these cases: +* If $c \in \\{0, 1, 4, 5\\}:$ + * If $g(u) = 0$ or $g(x) = 0$, return $\bot$ (even curves only). + * If $g(-u-x)$ is square, return $\bot.$ + * Let $s = -g(u)/(u^2 + ux + x^2 + a)$ (cannot cause division by zero). + * Let $v = x.$ +* Otherwise, when $c \in \\{2, 3, 6, 7\\}:$ + * Let $s = x-u.$ + * Let $r = \sqrt{-s(4g(u) + sh(u))}.$ + * If $c \in \\{3, 7\\}$ and $r=0$, return $\bot.$ + * Let $v = (r/s - u)/2.$ +* Let $w = \sqrt{s}.$ +* Depending on $c:$ + * If $c \in \\{0, 2\\}:$ return $P_u^{'-1}(v, w).$ + * If $c \in \\{1, 3\\}:$ return $P_u^{'-1}(-u-v, w).$ + * If $c \in \\{4, 6\\}:$ return $P_u^{'-1}(v, -w).$ + * If $c \in \\{5, 7\\}:$ return $P_u^{'-1}(-u-v, -w).$ + +Given any $u$, using this algorithm over all $x$ and $c$ values, every $t$ value will be reached exactly once, +for an $x$ for which $F_u(t) = x$ holds, except for these cases that will not be reached: +* (Obviously) all cases where $P_u(t)$ is not defined: + * For $a=0$ curves, when $u=0$, $t=0$, or $g(u) = -t^2.$ + * For $a \neq 0$ curves, when $h(u)t^2 = -1$, $X_0(u) = 0$, or $Y_0(u) (1 - h(u) t^2) = 2X_0(u)t.$ +* When $g(u)=0$, the potentially many $t$ values that decode to an $x$ satisfying $g(x)=0$ using the $x_2$ formula. These were excluded by the $g(u)=0$ condition in the $c \in \\{0, 1, 4, 5\\}$ branch. + +These cases form a negligible subset of all $(u, t)$ for cryptographically sized curves. + +### 3.5 Encoding for `secp256k1` + +Specialized for odd-ordered $a=0$ curves: + +**Define** $G_{c,u}(x)$ as: +* If $u=0$, return $\bot.$ +* If $c \in \\{0, 1, 4, 5\\}:$ + * If $(-u-x)^3 + b$ is square, return $\bot$ + * Let $s = -(u^3 + b)/(u^2 + ux + x^2)$ (cannot cause division by 0). + * Let $v = x.$ +* Otherwise, when $c \in \\{2, 3, 6, 7\\}:$ + * Let $s = x-u.$ + * Let $r = \sqrt{-s(4(u^3 + b) + 3su^2)}.$ + * If $c \in \\{3, 7\\}$ and $r=0$, return $\bot.$ + * Let $v = (r/s - u)/2.$ +* Let $w = \sqrt{s}.$ +* Depending on $c:$ + * If $c \in \\{0, 2\\}:$ return $w(\frac{\sqrt{-3}-1}{2}u - v).$ + * If $c \in \\{1, 3\\}:$ return $w(\frac{\sqrt{-3}+1}{2}u + v).$ + * If $c \in \\{4, 6\\}:$ return $w(\frac{-\sqrt{-3}+1}{2}u + v).$ + * If $c \in \\{5, 7\\}:$ return $w(\frac{-\sqrt{-3}-1}{2}u - v).$ + +This is implemented in `secp256k1_ellswift_xswiftec_inv_var`. + +And the x-only ElligatorSwift encoding algorithm is still: + +**Define** *ElligatorSwift(x)* as: +* Loop: + * Pick a uniformly random field element $u.$ + * Pick a uniformly random integer $c$ in $[0,8).$ + * Let $t = G_{c,u}(x).$ + * If $t \neq \bot$, return $(u, t)$; restart loop otherwise. + +Note that this logic does not take the remapped $u=0$, $t=0$, and $g(u) = -t^2$ cases into account; it just avoids them. +While it is not impossible to make the encoder target them, this would increase the maximum number of $t$ values for a given $(u, x)$ +combination beyond 8, and thereby slow down the ElligatorSwift loop proportionally, for a negligible gain in uniformity. + +## 4. Encoding and decoding full *(x, y)* coordinates + +So far we have only addressed encoding and decoding x-coordinates, but in some cases an encoding +for full points with $(x, y)$ coordinates is desirable. It is possible to encode this information +in $t$ as well. + +Note that for any $(X, Y) \in S_u$, $(\pm X, \pm Y)$ are all on $S_u.$ Moreover, all of these are +mapped to the same x-coordinate. Negating $X$ or negating $Y$ just results in $x_1$ and $x_2$ +being swapped, and does not affect $x_3.$ This will not change the outcome x-coordinate as the order +of $x_1$ and $x_2$ only matters if both were to be valid, and in that case $x_3$ would be used instead. + +Still, these four $(X, Y)$ combinations all correspond to distinct $t$ values, so we can encode +the sign of the y-coordinate in the sign of $X$ or the sign of $Y.$ They correspond to the +four distinct $P_u^{'-1}$ calls in the definition of $G_{u,c}.$ + +**Note**: In the paper, the sign of the y coordinate is encoded in a separately-coded bit. + +To encode the sign of $y$ in the sign of $Y:$ + +**Define** *Decode(u, t)* for full $(x, y)$ as: +* Let $(X, Y) = P_u(t).$ +* Let $x$ be the first value in $(u + 4Y^2, \frac{-X}{2Y} - \frac{u}{2}, \frac{X}{2Y} - \frac{u}{2})$ for which $g(x)$ is square. +* Let $y = \sqrt{g(x)}.$ +* If $sign(y) = sign(Y)$, return $(x, y)$; otherwise return $(x, -y).$ + +And encoding would be done using a $G_{c,u}(x, y)$ function defined as: + +**Define** $G_{c,u}(x, y)$ as: +* If $c \in \\{0, 1\\}:$ + * If $g(u) = 0$ or $g(x) = 0$, return $\bot$ (even curves only). + * If $g(-u-x)$ is square, return $\bot.$ + * Let $s = -g(u)/(u^2 + ux + x^2 + a)$ (cannot cause division by zero). + * Let $v = x.$ +* Otherwise, when $c \in \\{2, 3\\}:$ + * Let $s = x-u.$ + * Let $r = \sqrt{-s(4g(u) + sh(u))}.$ + * If $c = 3$ and $r = 0$, return $\bot.$ + * Let $v = (r/s - u)/2.$ +* Let $w = \sqrt{s}.$ +* Let $w' = w$ if $sign(w/2) = sign(y)$; $-w$ otherwise. +* Depending on $c:$ + * If $c \in \\{0, 2\\}:$ return $P_u^{'-1}(v, w').$ + * If $c \in \\{1, 3\\}:$ return $P_u^{'-1}(-u-v, w').$ + +Note that $c$ now only ranges $[0,4)$, as the sign of $w'$ is decided based on that of $y$, rather than on $c.$ +This change makes some valid encodings unreachable: when $y = 0$ and $sign(Y) \neq sign(0)$. + +In the above logic, $sign$ can be implemented in several ways, such as parity of the integer representation +of the input field element (for prime-sized fields) or the quadratic residuosity (for fields where +$-1$ is not square). The choice does not matter, as long as it only takes on two possible values, and for $x \neq 0$ it holds that $sign(x) \neq sign(-x)$. + +### 4.1 Full *(x, y)* coordinates for `secp256k1` + +For $a=0$ curves, there is another option. Note that for those, +the $P_u(t)$ function translates negations of $t$ to negations of (both) $X$ and $Y.$ Thus, we can use $sign(t)$ to +encode the y-coordinate directly. Combined with the earlier remapping to guarantee all inputs land on the curve, we get +as decoder: + +**Define** *Decode(u, t)* as: +* Let $u'=u$ if $u \neq 0$; $1$ otherwise. +* Let $t'=t$ if $t \neq 0$; $1$ otherwise. +* Let $t''=t'$ if $u'^3 + b + t'^2 \neq 0$; $2t'$ otherwise. +* Let $X = \dfrac{u'^3 + b - t''^2}{2t''}.$ +* Let $Y = \dfrac{X + t''}{u'\sqrt{-3}}.$ +* Let $x$ be the first element of $(u' + 4Y^2, \frac{-X}{2Y} - \frac{u'}{2}, \frac{X}{2Y} - \frac{u'}{2})$ for which $g(x)$ is square. +* Let $y = \sqrt{g(x)}.$ +* Return $(x, y)$ if $sign(y) = sign(t)$; $(x, -y)$ otherwise. + +This is implemented in `secp256k1_ellswift_swiftec_var`. The used $sign(x)$ function is the parity of $x$ when represented as in integer in $[0,q).$ + +The corresponding encoder would invoke the x-only one, but negating the output $t$ if $sign(t) \neq sign(y).$ + +This is implemented in `secp256k1_ellswift_elligatorswift_var`. + +Note that this is only intended for encoding points where both the x-coordinate and y-coordinate are unpredictable. When encoding x-only points +where the y-coordinate is implicitly even (or implicitly square, or implicitly in $[0,q/2]$), the encoder in +[Section 3.5](#35-encoding-for-secp256k1) must be used, or a bias is reintroduced that undoes all the benefit of using ElligatorSwift +in the first place. diff --git a/include/secp256k1_ellswift.h b/include/secp256k1_ellswift.h new file mode 100644 index 0000000000000..995402cf976a5 --- /dev/null +++ b/include/secp256k1_ellswift.h @@ -0,0 +1,170 @@ +#ifndef SECP256K1_ELLSWIFT_H +#define SECP256K1_ELLSWIFT_H + +#include "secp256k1.h" + +#ifdef __cplusplus +extern "C" { +#endif + +/* This module provides an implementation of ElligatorSwift as well as + * a version of x-only ECDH using it. + * + * ElligatorSwift is described in https://eprint.iacr.org/2022/759 by + * Chavez-Saab, Rodriguez-Henriquez, and Tibouchi. It permits encoding + * public keys in 64-byte objects which are indistinguishable from + * uniformly random. + * + * Let f be the function from pairs of field elements to point X coordinates, + * defined as follows (all operations modulo p = 2^256 - 2^32 - 977) + * f(u,t): + * - Let C = 0xa2d2ba93507f1df233770c2a797962cc61f6d15da14ecd47d8d27ae1cd5f852, + * a square root of -3. + * - If u=0, set u=1 instead. + * - If t=0, set t=1 instead. + * - If u^3 + t^2 + 7 = 0, multiply t by 2. + * - Let X = (u^3 + 7 - t^2) / (2 * t) + * - Let Y = (X + t) / (C * u) + * - Return the first of [u + 4 * Y^2, (-X/Y - u) / 2, (X/Y - u) / 2] that is an + * X coordinate on the curve (at least one of them is, for any inputs u and t). + * + * Then an ElligatorSwift encoding of x consists of the 32-byte big-endian + * encodings of field elements u and t concatenated, where f(u,t) = x. + * The encoding algorithm is described in the paper, and effectively picks a + * uniformly random pair (u,t) among those which encode x. + * + * If the Y coordinate is relevant, it is given the same parity as t. + * + * Changes w.r.t. the the paper: + * - The u=0, t=0, and u^3+t^2+7=0 conditions result in decoding to the point + * at infinity in the paper. Here they are remapped to finite points. + * - The paper uses an additional encoding bit for the parity of y. Here the + * parity of t is used (negating t does not affect the decoded x coordinate, + * so this is possible). + */ + +/** A pointer to a function used for hashing the shared X coordinate along + * with the encoded public keys to a uniform shared secret. + * + * Returns: 1 if a shared secret was was successfully computed. + * 0 will cause secp256k1_ellswift_xdh to fail and return 0. + * Other return values are not allowed, and the behaviour of + * secp256k1_ellswift_xdh is undefined for other return values. + * Out: output: pointer to an array to be filled by the function + * In: x32: pointer to the 32-byte serialized X coordinate + * of the resulting shared point + * ours64: pointer to the 64-byte encoded public key we sent + * to the other party + * theirs64: pointer to the 64-byte encoded public key we received + * from the other party + * data: arbitrary data pointer that is passed through + */ +typedef int (*secp256k1_ellswift_xdh_hash_function)( + unsigned char *output, + const unsigned char *x32, + const unsigned char *ours64, + const unsigned char *theirs64, + void *data +); + +/** An implementation of an secp256k1_ellswift_xdh_hash_function which uses + * SHA256(key1 || key2 || x32), where (key1, key2) = sorted([ours64, theirs64]), and + * ignores data. The sorting is lexicographic. */ +SECP256K1_API extern const secp256k1_ellswift_xdh_hash_function secp256k1_ellswift_xdh_hash_function_sha256; + +/** A default secp256k1_ellswift_xdh_hash_function, currently secp256k1_ellswift_xdh_hash_function_sha256. */ +SECP256K1_API extern const secp256k1_ellswift_xdh_hash_function secp256k1_ellswift_xdh_hash_function_default; + +/* Construct a 64-byte ElligatorSwift encoding of a given pubkey. + * + * Returns: 1 when pubkey is valid. + * Args: ctx: pointer to a context object + * Out: ell64: pointer to a 64-byte array to be filled + * In: pubkey: a pointer to a secp256k1_pubkey containing an + * initialized public key + * rnd32: pointer to 32 bytes of entropy (must be unpredictable) + * + * This function runs in variable time. + */ +SECP256K1_API int secp256k1_ellswift_encode( + const secp256k1_context* ctx, + unsigned char *ell64, + const secp256k1_pubkey *pubkey, + const unsigned char *rnd32 +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4); + +/** Decode a 64-bytes ElligatorSwift encoded public key. + * + * Returns: always 1 + * Args: ctx: pointer to a context object + * Out: pubkey: pointer to a secp256k1_pubkey that will be filled + * In: ell64: pointer to a 64-byte array to decode + * + * This function runs in variable time. + */ +SECP256K1_API int secp256k1_ellswift_decode( + const secp256k1_context* ctx, + secp256k1_pubkey *pubkey, + const unsigned char *ell64 +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3); + +/** Compute an ElligatorSwift public key for a secret key. + * + * Returns: 1: secret was valid, public key was stored. + * 0: secret was invalid, try again. + * Args: ctx: pointer to a context object, initialized for signing. + * Out: ell64: pointer to a 64-byte area to receive the ElligatorSwift public key + * In: seckey32: pointer to a 32-byte secret key. + * auxrand32: (optional) pointer to 32 bytes of additional randomness + * + * Constant time in seckey and auxrand32, but not in the resulting public key. + * + * This function can be used instead of calling secp256k1_ec_pubkey_create followed + * by secp256k1_ellswift_encode. It is safer, as it can use the secret key as + * entropy for the encoding. That means that if the secret key itself is + * unpredictable, no additional auxrand32 is needed to achieve indistinguishability + * of the encoding. + */ +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ellswift_create( + const secp256k1_context* ctx, + unsigned char *ell64, + const unsigned char *seckey32, + const unsigned char *auxrand32 +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3); + +/** Given a private key, and ElligatorSwift public keys sent in both directions, + * compute a shared secret using x-only Diffie-Hellman. + * + * Returns: 1: shared secret was succesfully computed + * 0: secret was invalid or hashfp returned 0 + * Args: ctx: pointer to a context object. + * Out: output: pointer to an array to be filled by hashfp. + * In: theirs64: a pointer to the 64-byte ElligatorSwift public key received from the other party. + * ours64: a pointer to the 64-byte ElligatorSwift public key sent to the other party. + * seckey32: a pointer to the 32-byte private key corresponding to ours64. + * hashfp: pointer to a hash function. If NULL, + * secp256k1_elswift_xdh_hash_function_default is used + * (in which case, 32 bytes will be written to output). + * data: arbitrary data pointer that is passed through to hashfp + * (ignored for secp256k1_ellswift_xdh_hash_function_default). + * + * Constant time in seckey32. + * + * This function is more efficient than decoding the public keys, and performing ECDH on them. + */ +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ellswift_xdh( + const secp256k1_context* ctx, + unsigned char *output, + const unsigned char* theirs64, + const unsigned char* ours64, + const unsigned char* seckey32, + secp256k1_ellswift_xdh_hash_function hashfp, + void *data +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4) SECP256K1_ARG_NONNULL(5); + + +#ifdef __cplusplus +} +#endif + +#endif /* SECP256K1_ELLSWIFT_H */ diff --git a/src/bench.c b/src/bench.c index 833f70718b584..9b5afe323d5d8 100644 --- a/src/bench.c +++ b/src/bench.c @@ -121,6 +121,22 @@ static void bench_sign_run(void* arg, int iters) { } } +static void bench_keygen_run(void* arg, int iters) { + int i; + bench_sign_data *data = (bench_sign_data*)arg; + + for (i = 0; i < iters; i++) { + unsigned char pub33[33]; + size_t len = 33; + secp256k1_pubkey pubkey; + CHECK(secp256k1_ec_pubkey_create(data->ctx, &pubkey, data->key)); + CHECK(secp256k1_ec_pubkey_serialize(data->ctx, pub33, &len, &pubkey, SECP256K1_EC_COMPRESSED)); + memcpy(data->key, pub33 + 1, 32); + data->key[17] ^= i; + } +} + + #ifdef ENABLE_MODULE_ECDH # include "modules/ecdh/bench_impl.h" #endif @@ -133,6 +149,10 @@ static void bench_sign_run(void* arg, int iters) { # include "modules/schnorrsig/bench_impl.h" #endif +#ifdef ENABLE_MODULE_ELLSWIFT +# include "modules/ellswift/bench_impl.h" +#endif + int main(int argc, char** argv) { int i; secp256k1_pubkey pubkey; @@ -145,7 +165,9 @@ int main(int argc, char** argv) { /* Check for invalid user arguments */ char* valid_args[] = {"ecdsa", "verify", "ecdsa_verify", "sign", "ecdsa_sign", "ecdh", "recover", - "ecdsa_recover", "schnorrsig", "schnorrsig_verify", "schnorrsig_sign"}; + "ecdsa_recover", "schnorrsig", "schnorrsig_verify", "schnorrsig_sign", "ec", + "keygen", "ec_keygen", "ellswift", "encode", "ellswift_encode", "decode", + "ellswift_decode", "ellswift_keygen", "ellswift_ecdh"}; size_t valid_args_size = sizeof(valid_args)/sizeof(valid_args[0]); int invalid_args = have_invalid_args(argc, argv, valid_args, valid_args_size); @@ -207,6 +229,7 @@ int main(int argc, char** argv) { if (d || have_flag(argc, argv, "ecdsa") || have_flag(argc, argv, "verify") || have_flag(argc, argv, "ecdsa_verify")) run_benchmark("ecdsa_verify", bench_verify, NULL, NULL, &data, 10, iters); if (d || have_flag(argc, argv, "ecdsa") || have_flag(argc, argv, "sign") || have_flag(argc, argv, "ecdsa_sign")) run_benchmark("ecdsa_sign", bench_sign_run, bench_sign_setup, NULL, &data, 10, iters); + if (d || have_flag(argc, argv, "ec") || have_flag(argc, argv, "keygen") || have_flag(argc, argv, "ec_keygen")) run_benchmark("ec_keygen", bench_keygen_run, bench_sign_setup, NULL, &data, 10, iters); secp256k1_context_destroy(data.ctx); @@ -225,5 +248,10 @@ int main(int argc, char** argv) { run_schnorrsig_bench(iters, argc, argv); #endif +#ifdef ENABLE_MODULE_ELLSWIFT + /* ElligatorSwift benchmarks */ + run_ellswift_bench(iters, argc, argv); +#endif + return 0; } diff --git a/src/ctime_tests.c b/src/ctime_tests.c index 713eb427d32f6..f90ddc72f514c 100644 --- a/src/ctime_tests.c +++ b/src/ctime_tests.c @@ -30,6 +30,10 @@ #include "../include/secp256k1_schnorrsig.h" #endif +#ifdef ENABLE_MODULE_ELLSWIFT +#include "../include/secp256k1_ellswift.h" +#endif + static void run_tests(secp256k1_context *ctx, unsigned char *key); int main(void) { @@ -80,6 +84,9 @@ static void run_tests(secp256k1_context *ctx, unsigned char *key) { #ifdef ENABLE_MODULE_EXTRAKEYS secp256k1_keypair keypair; #endif +#ifdef ENABLE_MODULE_ELLSWIFT + unsigned char ellswift[64]; +#endif for (i = 0; i < 32; i++) { msg[i] = i + 1; @@ -171,4 +178,22 @@ static void run_tests(secp256k1_context *ctx, unsigned char *key) { SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret)); CHECK(ret == 1); #endif + +#ifdef ENABLE_MODULE_ELLSWIFT + VALGRIND_MAKE_MEM_UNDEFINED(key, 32); + ret = secp256k1_ellswift_create(ctx, ellswift, key, NULL); + VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret)); + CHECK(ret == 1); + + VALGRIND_MAKE_MEM_UNDEFINED(key, 32); + ret = secp256k1_ellswift_create(ctx, ellswift, key, key); + VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret)); + CHECK(ret == 1); + + VALGRIND_MAKE_MEM_UNDEFINED(key, 32); + VALGRIND_MAKE_MEM_DEFINED(&ellswift, sizeof(ellswift)); + ret = secp256k1_ellswift_xdh(ctx, msg, ellswift, ellswift, key, NULL, NULL); + VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret)); + CHECK(ret == 1); +#endif } diff --git a/src/ecmult_const.h b/src/ecmult_const.h index f891f3f306709..2c7018b8d400f 100644 --- a/src/ecmult_const.h +++ b/src/ecmult_const.h @@ -18,4 +18,25 @@ */ static void secp256k1_ecmult_const(secp256k1_gej *r, const secp256k1_ge *a, const secp256k1_scalar *q, int bits); +/** + * Same as secp256k1_ecmult_const, but takes in an x coordinate of the base point + * only, specified as fraction n/d (numerator/denominator). Only the x coordinate of the result is + * returned. + * + * If known_on_curve is 0, a verification is performed that n/d is a valid X + * coordinate, and 0 is returned if not. Otherwise, 1 is returned. + * + * d being NULL is interpreted as d=1. + * + * Constant time in the value of q, but not any other inputs. + */ +static int secp256k1_ecmult_const_xonly( + secp256k1_fe* r, + const secp256k1_fe *n, + const secp256k1_fe *d, + const secp256k1_scalar *q, + int bits, + int known_on_curve +); + #endif /* SECP256K1_ECMULT_CONST_H */ diff --git a/src/ecmult_const_impl.h b/src/ecmult_const_impl.h index 12dbcc6c5b692..7b5c60b22abdd 100644 --- a/src/ecmult_const_impl.h +++ b/src/ecmult_const_impl.h @@ -228,4 +228,130 @@ static void secp256k1_ecmult_const(secp256k1_gej *r, const secp256k1_ge *a, cons secp256k1_fe_mul(&r->z, &r->z, &Z); } +static int secp256k1_ecmult_const_xonly(secp256k1_fe* r, const secp256k1_fe *n, const secp256k1_fe *d, const secp256k1_scalar *q, int bits, int known_on_curve) { + + /* This algorithm is a generalization of Peter Dettman's technique for + * avoiding the square root in a random-basepoint x-only multiplication + * on a Weierstrass curve: + * https://mailarchive.ietf.org/arch/msg/cfrg/7DyYY6gg32wDgHAhgSb6XxMDlJA/ + * + * + * === Background: the effective affine technique === + * + * Let phi_u be the isomorphism that maps (x, y) on secp256k1 curve y^2 = x^3 + 7 to + * x' = u^2*x, y' = u^3*y on curve y'^2 = x'^3 + u^6*7. This new curve has the same order as + * the original (it is isomorphic), but moreover, has the same addition/doubling formulas, as + * the curve b=7 coefficient does not appear in those formulas (or at least does not appear in + * the formulas implemented in this codebase, both affine and Jacobian). See also Example 9.5.2 + * in https://www.math.auckland.ac.nz/~sgal018/crypto-book/ch9.pdf. + * + * This means any linear combination of secp256k1 points can be computed by applying phi_u + * (with non-zero u) on all input points (including the generator, if used), computing the + * linear combination on the isomorphic curve (using the same group laws), and then applying + * phi_u^{-1} to get back to secp256k1. + * + * Switching to Jacobian coordinates, note that phi_u applied to (X, Y, Z) is simply + * (X, Y, Z/u). Thus, if we want to compute (X1, Y1, Z) + (X2, Y2, Z), with identical Z + * coordinates, we can use phi_Z to transform it to (X1, Y1, 1) + (X2, Y2, 1) on an isomorphic + * curve where the affine addition formula can be used instead. + * If (X3, Y3, Z3) = (X1, Y1) + (X2, Y2) on that curve, then our answer on secp256k1 is + * (X3, Y3, Z3*Z). + * + * This is the effective affine technique: if we have a linear combination of group elements + * to compute, and all those group elements have the same Z coordinate, we can simply pretend + * that all those Z coordinates are 1, perform the computation that way, and then multiply the + * original Z coordinate back in. + * + * The technique works on any a=0 short Weierstrass curve. It is possible to generalize it to + * other curves too, but there the isomorphic curves will have different 'a' coefficients, + * which typically does affect the group laws. + * + * + * === Avoiding the square root for x-only point multiplication === + * + * In this function, we want to compute the X coordinate of q*(n/d, y), for + * y = sqrt((n/d)^3 + 7). Its negation would also be a valid Y coordinate, but by convention + * we pick whatever sqrt returns (which we assume to be a deterministic function). + * + * Let g = y^2*d^3 = n^3 + 7*d^3. This also means y = sqrt(g/d^3). + * Further let v = sqrt(d*g), which must exist as d*g = y^2*d^4 = (y*d^2)^2. + * + * The input point (n/d, y) also has Jacobian coordinates: + * + * (n/d, y, 1) + * = (n/d * v^2, y * v^3, v) + * = (n/d * d*g, y * sqrt(d^3*g^3), v) + * = (n/d * d*g, sqrt(y^2 * d^3*g^3), v) + * = (n*g, sqrt(g/d^3 * d^3*g^3), v) + * = (n*g, sqrt(g^4), v) + * = (n*g, g^2, v) + * + * It is easy to verify that both (n*g, g^2, v) and its negation (n*g, -g^2, v) have affine X + * coordinate n/d, and this holds even when the square root function doesn't have a + * determinstic sign. We choose the (n*g, g^2, v) version. + * + * Now switch to the effective affine curve using phi_v, where the input point has coordinates + * (n*g, g^2). Compute (X, Y, Z) = q * (n*g, g^2) there. + * + * Back on secp256k1, that means q * (n*g, g^2, v) = (X, Y, v*Z). This last point has affine X + * coordinate X / (v^2*Z^2) = X / (d*g*Z^2). Determining the affine Y coordinate would involve + * a square root, but as long as we only care about the resulting X coordinate, no square root + * is needed anywhere in this computation. + */ + + secp256k1_fe g, i; + secp256k1_ge p; + secp256k1_gej rj; + + /* Compute g = (n^3 + B*d^3). */ + secp256k1_fe_sqr(&g, n); + secp256k1_fe_mul(&g, &g, n); + if (d) { + secp256k1_fe b; + secp256k1_fe_sqr(&b, d); + VERIFY_CHECK(SECP256K1_B <= 8); /* magnitude of b will be <= 8 after the next call */ + secp256k1_fe_mul_int(&b, SECP256K1_B); + secp256k1_fe_mul(&b, &b, d); + secp256k1_fe_add(&g, &b); + if (!known_on_curve) { + /* We need to determine whether (n/d)^3 + 7 is square. + * + * is_square((n/d)^3 + 7) + * <=> is_square(((n/d)^3 + 7) * d^4) + * <=> is_square((n^3 + 7*d^3) * d) + * <=> is_square(g * d) + */ + secp256k1_fe c; + secp256k1_fe_mul(&c, &g, d); + if (!secp256k1_fe_is_square_var(&c)) return 0; + } + } else { + secp256k1_fe_add_int(&g, SECP256K1_B); + if (!known_on_curve) { + /* g at this point equals x^3 + 7. Test if it is square. */ + if (!secp256k1_fe_is_square_var(&g)) return 0; + } + } + + /* Compute base point P = (n*g, g^2), the effective affine version of (n*g, g^2, v), which has + * corresponding affine X coordinate n/d. */ + secp256k1_fe_mul(&p.x, &g, n); + secp256k1_fe_sqr(&p.y, &g); + p.infinity = 0; + + /* Perform x-only EC multiplication of P with q. */ + secp256k1_ecmult_const(&rj, &p, q, bits); + + /* The resulting (X, Y, Z) point on the effective-affine isomorphic curve corresponds to + * (X, Y, Z*v) on the secp256k1 curve. The affine version of that has X coordinate + * (X / (Z^2*d*g)). */ + secp256k1_fe_sqr(&i, &rj.z); + secp256k1_fe_mul(&i, &i, &g); + if (d) secp256k1_fe_mul(&i, &i, d); + secp256k1_fe_inv(&i, &i); + secp256k1_fe_mul(r, &rj.x, &i); + + return 1; +} + #endif /* SECP256K1_ECMULT_CONST_IMPL_H */ diff --git a/src/group.h b/src/group.h index b79ba597dbbbc..e966c2ba7827b 100644 --- a/src/group.h +++ b/src/group.h @@ -51,6 +51,12 @@ static void secp256k1_ge_set_xy(secp256k1_ge *r, const secp256k1_fe *x, const se * for Y. Return value indicates whether the result is valid. */ static int secp256k1_ge_set_xo_var(secp256k1_ge *r, const secp256k1_fe *x, int odd); +/** Determine whether x is a valid X coordinate on the curve. */ +static int secp256k1_ge_x_on_curve_var(const secp256k1_fe *x); + +/** Determine whether fraction xn/xd is a valid X coordinate on the curve. */ +static int secp256k1_ge_x_frac_on_curve_var(const secp256k1_fe *xn, const secp256k1_fe *xd); + /** Check whether a group element is the point at infinity. */ static int secp256k1_ge_is_infinity(const secp256k1_ge *a); diff --git a/src/group_impl.h b/src/group_impl.h index 82ce3f8d8bb75..0ade6077964ea 100644 --- a/src/group_impl.h +++ b/src/group_impl.h @@ -727,4 +727,29 @@ static int secp256k1_ge_is_in_correct_subgroup(const secp256k1_ge* ge) { #endif } +static int secp256k1_ge_x_on_curve_var(const secp256k1_fe* x) +{ + secp256k1_fe c; + secp256k1_fe_sqr(&c, x); + secp256k1_fe_mul(&c, &c, x); + secp256k1_fe_add_int(&c, SECP256K1_B); + return secp256k1_fe_is_square_var(&c); +} + +static int secp256k1_ge_x_frac_on_curve_var(const secp256k1_fe* xn, const secp256k1_fe* xd) { + /* We want to determine whether (xn/xd) is on the curve. + * + * (xn/xd)^3 + 7 is square <=> xd*xn^3 + 7*xd^4 is square (multiplying by xd^4, a square). + */ + secp256k1_fe r, t; + secp256k1_fe_mul(&r, xd, xn); /* r = xd*xn */ + secp256k1_fe_sqr(&t, xn); /* t = xn^2 */ + secp256k1_fe_mul(&r, &r, &t); /* r = xd*xn^3 */ + secp256k1_fe_sqr(&t, xd); /* t = xd^2 */ + secp256k1_fe_sqr(&t, &t); /* t = xd^4 */ + secp256k1_fe_mul_int(&t, SECP256K1_B); /* t = 7*xd^4 */ + secp256k1_fe_add(&r, &t); /* r = xd*xn^3 + 7*xd^4 */ + return secp256k1_fe_is_square_var(&r); +} + #endif /* SECP256K1_GROUP_IMPL_H */ diff --git a/src/modinv32_impl.h b/src/modinv32_impl.h index 643750560e090..8e400b697b098 100644 --- a/src/modinv32_impl.h +++ b/src/modinv32_impl.h @@ -232,7 +232,7 @@ static int32_t secp256k1_modinv32_divsteps_30(int32_t zeta, uint32_t f0, uint32_ return zeta; } -/* inv256[i] = -(2*i+1)^-1 (mod 256) */ +/* secp256k1_modinv32_inv256[i] = -(2*i+1)^-1 (mod 256) */ static const uint8_t secp256k1_modinv32_inv256[128] = { 0xFF, 0x55, 0x33, 0x49, 0xC7, 0x5D, 0x3B, 0x11, 0x0F, 0xE5, 0xC3, 0x59, 0xD7, 0xED, 0xCB, 0x21, 0x1F, 0x75, 0x53, 0x69, 0xE7, 0x7D, 0x5B, 0x31, diff --git a/src/modules/ellswift/Makefile.am.include b/src/modules/ellswift/Makefile.am.include new file mode 100644 index 0000000000000..e7efea29819b2 --- /dev/null +++ b/src/modules/ellswift/Makefile.am.include @@ -0,0 +1,4 @@ +include_HEADERS += include/secp256k1_ellswift.h +noinst_HEADERS += src/modules/ellswift/bench_impl.h +noinst_HEADERS += src/modules/ellswift/main_impl.h +noinst_HEADERS += src/modules/ellswift/tests_impl.h diff --git a/src/modules/ellswift/bench_impl.h b/src/modules/ellswift/bench_impl.h new file mode 100644 index 0000000000000..f562955dfab18 --- /dev/null +++ b/src/modules/ellswift/bench_impl.h @@ -0,0 +1,100 @@ +/*********************************************************************** + * Copyright (c) 2022 Pieter Wuille * + * Distributed under the MIT software license, see the accompanying * + * file COPYING or https://www.opensource.org/licenses/mit-license.php.* + ***********************************************************************/ + +#ifndef SECP256K1_MODULE_ELLSWIFT_BENCH_H +#define SECP256K1_MODULE_ELLSWIFT_BENCH_H + +#include "../../../include/secp256k1_ellswift.h" + +typedef struct { + secp256k1_context *ctx; + secp256k1_pubkey point[256]; + unsigned char rnd64[64]; +} bench_ellswift_data; + +static void bench_ellswift_setup(void* arg) { + int i; + bench_ellswift_data *data = (bench_ellswift_data*)arg; + static const unsigned char init[64] = { + 0x78, 0x1f, 0xb7, 0xd4, 0x67, 0x7f, 0x08, 0x68, + 0xdb, 0xe3, 0x1d, 0x7f, 0x1b, 0xb0, 0xf6, 0x9e, + 0x0a, 0x64, 0xca, 0x32, 0x9e, 0xc6, 0x20, 0x79, + 0x03, 0xf3, 0xd0, 0x46, 0x7a, 0x0f, 0xd2, 0x21, + 0xb0, 0x2c, 0x46, 0xd8, 0xba, 0xca, 0x26, 0x4f, + 0x8f, 0x8c, 0xd4, 0xdd, 0x2d, 0x04, 0xbe, 0x30, + 0x48, 0x51, 0x1e, 0xd4, 0x16, 0xfd, 0x42, 0x85, + 0x62, 0xc9, 0x02, 0xf9, 0x89, 0x84, 0xff, 0xdc + }; + memcpy(data->rnd64, init, 64); + for (i = 0; i < 256; ++i) { + int j; + CHECK(secp256k1_ellswift_decode(data->ctx, &data->point[i], data->rnd64)); + for (j = 0; j < 64; ++j) { + data->rnd64[j] += 1; + } + } + CHECK(secp256k1_ellswift_encode(data->ctx, data->rnd64, &data->point[255], init + 16)); +} + +static void bench_ellswift_encode(void* arg, int iters) { + int i; + bench_ellswift_data *data = (bench_ellswift_data*)arg; + + for (i = 0; i < iters; i++) { + CHECK(secp256k1_ellswift_encode(data->ctx, data->rnd64, &data->point[i & 255], data->rnd64 + 16)); + } +} + +static void bench_ellswift_create(void* arg, int iters) { + int i; + bench_ellswift_data *data = (bench_ellswift_data*)arg; + + for (i = 0; i < iters; i++) { + unsigned char buf[64]; + CHECK(secp256k1_ellswift_create(data->ctx, buf, data->rnd64, data->rnd64 + 32)); + memcpy(data->rnd64, buf, 64); + } +} + +static void bench_ellswift_decode(void* arg, int iters) { + int i; + secp256k1_pubkey out; + size_t len; + bench_ellswift_data *data = (bench_ellswift_data*)arg; + + for (i = 0; i < iters; i++) { + CHECK(secp256k1_ellswift_decode(data->ctx, &out, data->rnd64) == 1); + len = 33; + CHECK(secp256k1_ec_pubkey_serialize(data->ctx, data->rnd64 + (i % 32), &len, &out, SECP256K1_EC_COMPRESSED)); + } +} + +static void bench_ellswift_xdh(void* arg, int iters) { + int i; + bench_ellswift_data *data = (bench_ellswift_data*)arg; + + for (i = 0; i < iters; i++) { + CHECK(secp256k1_ellswift_xdh(data->ctx, data->rnd64 + (i % 33), data->rnd64, data->rnd64, data->rnd64 + ((i + 16) % 33), NULL, NULL) == 1); + } +} + +void run_ellswift_bench(int iters, int argc, char** argv) { + bench_ellswift_data data; + int d = argc == 1; + + /* create a context with signing capabilities */ + data.ctx = secp256k1_context_create(SECP256K1_CONTEXT_SIGN); + memset(data.rnd64, 11, sizeof(data.rnd64)); + + if (d || have_flag(argc, argv, "ellswift") || have_flag(argc, argv, "encode") || have_flag(argc, argv, "ellswift_encode")) run_benchmark("ellswift_encode", bench_ellswift_encode, bench_ellswift_setup, NULL, &data, 10, iters); + if (d || have_flag(argc, argv, "ellswift") || have_flag(argc, argv, "decode") || have_flag(argc, argv, "ellswift_decode")) run_benchmark("ellswift_decode", bench_ellswift_decode, bench_ellswift_setup, NULL, &data, 10, iters); + if (d || have_flag(argc, argv, "ellswift") || have_flag(argc, argv, "keygen") || have_flag(argc, argv, "ellswift_keygen")) run_benchmark("ellswift_keygen", bench_ellswift_create, bench_ellswift_setup, NULL, &data, 10, iters); + if (d || have_flag(argc, argv, "ellswift") || have_flag(argc, argv, "ecdh") || have_flag(argc, argv, "ellswift_ecdh")) run_benchmark("ellswift_ecdh", bench_ellswift_xdh, bench_ellswift_setup, NULL, &data, 10, iters); + + secp256k1_context_destroy(data.ctx); +} + +#endif /* SECP256K1_MODULE_ellswift_BENCH_H */ diff --git a/src/modules/ellswift/main_impl.h b/src/modules/ellswift/main_impl.h new file mode 100644 index 0000000000000..b408a8b66a33c --- /dev/null +++ b/src/modules/ellswift/main_impl.h @@ -0,0 +1,492 @@ +/*********************************************************************** + * Copyright (c) 2022 Pieter Wuille * + * Distributed under the MIT software license, see the accompanying * + * file COPYING or https://www.opensource.org/licenses/mit-license.php.* + ***********************************************************************/ + +#ifndef SECP256K1_MODULE_ELLSWIFT_MAIN_H +#define SECP256K1_MODULE_ELLSWIFT_MAIN_H + +#include "../../../include/secp256k1.h" +#include "../../../include/secp256k1_ellswift.h" +#include "../../hash.h" + +/** c1 = (sqrt(-3)-1)/2 */ +static const secp256k1_fe secp256k1_ellswift_c1 = SECP256K1_FE_CONST(0x851695d4, 0x9a83f8ef, 0x919bb861, 0x53cbcb16, 0x630fb68a, 0xed0a766a, 0x3ec693d6, 0x8e6afa40); +/** c2 = (-sqrt(-3)-1)/2 = -(c1+1) */ +static const secp256k1_fe secp256k1_ellswift_c2 = SECP256K1_FE_CONST(0x7ae96a2b, 0x657c0710, 0x6e64479e, 0xac3434e9, 0x9cf04975, 0x12f58995, 0xc1396c28, 0x719501ee); +/** c3 = (-sqrt(-3)+1)/2 = -c1 = c2+1 */ +static const secp256k1_fe secp256k1_ellswift_c3 = SECP256K1_FE_CONST(0x7ae96a2b, 0x657c0710, 0x6e64479e, 0xac3434e9, 0x9cf04975, 0x12f58995, 0xc1396c28, 0x719501ef); +/** c4 = (sqrt(-3)+1)/2 = -c2 = c1+1 */ +static const secp256k1_fe secp256k1_ellswift_c4 = SECP256K1_FE_CONST(0x851695d4, 0x9a83f8ef, 0x919bb861, 0x53cbcb16, 0x630fb68a, 0xed0a766a, 0x3ec693d6, 0x8e6afa41); + +/** Decode ElligatorSwift encoding (u, t) to a fraction xn/xd representing a curve X coordinate. */ +static void secp256k1_ellswift_xswiftec_frac_var(secp256k1_fe* xn, secp256k1_fe* xd, const secp256k1_fe* u, const secp256k1_fe* t) { + /* The implemented algorithm is the following (all operations in GF(p)): + * + * - c0 = sqrt(-3) = 0xa2d2ba93507f1df233770c2a797962cc61f6d15da14ecd47d8d27ae1cd5f852 + * - If u=0, set u=1. + * - If t=0, set t=1. + * - If u^3+7+t^2 = 0, set t=2*t. + * - Let X=(u^3+7-t^2)/(2*t) + * - Let Y=(X+t)/(c0*u) + * - If x3=u+4*Y^2 is a valid x coordinate, return x3. + * - If x2=(-X/Y-u)/2 is a valid x coordinare, return x2. + * - Return x1=(X/Y-u)/2 (which is now guaranteed to be a valid x coordinate). + * + * Introducing s=t^2, g=u^3+7, and simplifying x1=-(x2+u) we get: + * + * - ... + * - Let s=t^2 + * - Let g=u^3+7 + * - If g+s=0, set t=2*t, s=4*s + * - Let X=(g-s)/(2*t) + * - Let Y=(X+t)/(c0*u) = (g+s)/(2*c0*t*u) + * - If x3=u+4*Y^2 is a valid x coordinate, return x3. + * - If x2=(-X/Y-u)/2 is a valid x coordinate, return it. + * - Return x1=-(x2+u). + * + * Now substitute Y^2 = -(g+s)^2/(12*s*u^2) and X/Y = c0*u*(g-s)/(g+s) + * + * - ... + * - If g+s=0, set s=4*s + * - If x3=u-(g+s)^2/(3*s*u^2) is a valid x coordinate, return it. + * - If x2=(-c0*u*(g-s)/(g+s)-u)/2 is a valid x coordinate, return it. + * - Return x1=(c0*u*(g-s)/(g+s)-u)/2. + * + * Simplifying x2 using 2 additional constants: + * + * - c1 = (c0-1)/2 = 0x851695d49a83f8ef919bb86153cbcb16630fb68aed0a766a3ec693d68e6afa40 + * - c2 = (-c0-1)/2 = 0x7ae96a2b657c07106e64479eac3434e99cf0497512f58995c1396c28719501ee + * - ... + * - If x2=u*(c1*s+c2*g)/(g+s) is a valid x coordinate, return it. + * - ... + * + * Writing x3 as a fraction: + * + * - ... + * - If x3=(3*s*u^3-(g+s)^2)/(3*s*u^2) + * - ... + + * Overall, we get: + * + * - c1 = 0x851695d49a83f8ef919bb86153cbcb16630fb68aed0a766a3ec693d68e6afa40 + * - c2 = 0x7ae96a2b657c07106e64479eac3434e99cf0497512f58995c1396c28719501ee + * - If u=0, set u=1. + * - If t=0, set s=1, else set s=t^2 + * - Let g=u^3+7 + * - If g+s=0, set s=4*s + * - If x3=(3*s*u^3-(g+s)^2)/(3*s*u^2) is a valid x coordinate, return it. + * - If x2=u*(c1*s+c2*g)/(g+s) is a valid x coordinate, return it. + * - Return x1=-(x2+u) + */ + secp256k1_fe u1, s, g, p, d, n, l; + u1 = *u; + if (EXPECT(secp256k1_fe_normalizes_to_zero_var(&u1), 0)) u1 = secp256k1_fe_one; + secp256k1_fe_sqr(&s, t); + if (EXPECT(secp256k1_fe_normalizes_to_zero_var(t), 0)) s = secp256k1_fe_one; + secp256k1_fe_sqr(&l, &u1); /* l = u^2 */ + secp256k1_fe_mul(&g, &l, &u1); /* g = u^3 */ + secp256k1_fe_add_int(&g, SECP256K1_B); /* g = u^3 + 7 */ + p = g; /* p = g */ + secp256k1_fe_add(&p, &s); /* p = g+s */ + if (EXPECT(secp256k1_fe_normalizes_to_zero_var(&p), 0)) { + secp256k1_fe_mul_int(&s, 4); /* s = 4*s */ + /* recompute p = g+s */ + p = g; /* p = g */ + secp256k1_fe_add(&p, &s); /* p = g+s */ + } + secp256k1_fe_mul(&d, &s, &l); /* d = s*u^2 */ + secp256k1_fe_mul_int(&d, 3); /* d = 3*s*u^2 */ + secp256k1_fe_sqr(&l, &p); /* l = (g+s)^2 */ + secp256k1_fe_negate(&l, &l, 1); /* l = -(g+s)^2 */ + secp256k1_fe_mul(&n, &d, &u1); /* n = 3*s*u^3 */ + secp256k1_fe_add(&n, &l); /* n = 3*s*u^3-(g+s)^2 */ + if (secp256k1_ge_x_frac_on_curve_var(&n, &d)) { + /* Return n/d = (3*s*u^3-(g+s)^2)/(3*s*u^2) */ + *xn = n; + *xd = d; + return; + } + *xd = p; + secp256k1_fe_mul(&l, &secp256k1_ellswift_c1, &s); /* l = c1*s */ + secp256k1_fe_mul(&n, &secp256k1_ellswift_c2, &g); /* n = c2*g */ + secp256k1_fe_add(&n, &l); /* n = c1*s+c2*g */ + secp256k1_fe_mul(&n, &n, &u1); /* n = u*(c1*s+c2*g) */ + /* Possible optimization: in the invocation below, d^2 = (g+s)^2 is computed, + * which we already have computed above. This could be deduplicated. */ + if (secp256k1_ge_x_frac_on_curve_var(&n, &p)) { + /* Return n/p = u*(c1*s+c2*g)/(g+s) */ + *xn = n; + return; + } + secp256k1_fe_mul(&l, &p, &u1); /* l = u*(g+s) */ + secp256k1_fe_add(&n, &l); /* n = u*(c1*s+c2*g)+u*g*s */ + secp256k1_fe_negate(xn, &n, 2); /* n = -u*(c1*s+c2*g)+u*g*s */ +#ifdef VERIFY + VERIFY_CHECK(secp256k1_ge_x_frac_on_curve_var(xn, &p)); +#endif + /* Return n/p = -(u*(c1*s+c2*g)/(g+s)+u) */ +} + +/** Decode ElligatorSwift encoding (u, t) to X coordinate. */ +static void secp256k1_ellswift_xswiftec_var(secp256k1_fe* x, const secp256k1_fe* u, const secp256k1_fe* t) { + secp256k1_fe xn, xd; + secp256k1_ellswift_xswiftec_frac_var(&xn, &xd, u, t); + secp256k1_fe_inv_var(&xd, &xd); + secp256k1_fe_mul(x, &xn, &xd); +} + +/** Decode ElligatorSwift encoding (u, t) to point P. */ +static void secp256k1_ellswift_swiftec_var(secp256k1_ge* p, const secp256k1_fe* u, const secp256k1_fe* t) { + secp256k1_fe x; + secp256k1_ellswift_xswiftec_var(&x, u, t); + secp256k1_ge_set_xo_var(p, &x, secp256k1_fe_is_odd(t)); +} + +/* Try to complete an ElligatorSwift encoding (u, t) for X coordinate x, given u and x. + * + * There may be up to 8 distinct t values such that (u, t) decodes back to x, but also + * fewer, or none at all. Each such partial inverse can be accessed individually using a + * distinct input argument c (in range 0-7), and some or all of these may return failure. + * The following guarantees exist: + * - Given (x, u), no two distinct c values give the same successful result t. + * - Every successful result maps back to x through secp256k1_ellswift_xswiftec_var. + * - Given (x, u), all t values that map back to x can be reached by combining the + * successful results from this function over all c values, with the exception of: + * - this function cannot be called with u=0 + * - no result with t=0 will be returned + * - no result for which u^3 + t^2 + 7 = 0 will be returned. + */ +static int secp256k1_ellswift_xswiftec_inv_var(secp256k1_fe* t, const secp256k1_fe* x_in, const secp256k1_fe* u_in, int c) { + /* The implemented algorithm is this (all arithmetic, except involving c, is mod p): + * + * - If (c & 2) = 0: + * - If (-x-u) is a valid X coordinate, fail. + * - Let s=-(u^3+7)/(u^2+u*x+x^2). + * - If s is not square, fail. + * - Let v=x. + * - If (c & 2) = 2: + * - Let s=x-u. + * - If s=0, fail. + * - If s is not square, fail. + * - Let r=sqrt(-s*(4*(u^3+7)+3*u^2*s)); fail if it doesn't exist. + * - If (c & 1) = 1 and r = 0, fail. + * - Let v=(r/s-u)/2. + * - Let w=sqrt(s). + * - If (c & 5) = 0: return -w*(c3*u + v) + * - If (c & 5) = 1: return w*(c4*u + v) + * - If (c & 5) = 4: return w*(c3*u + v) + * - If (c & 5) = 5: return -w*(c4*u + v) + */ + secp256k1_fe x = *x_in, u = *u_in, u2, g, v, s, m, r, q; + + /* Normalize. */ + secp256k1_fe_normalize_weak(&x); + secp256k1_fe_normalize_weak(&u); + + + if (!(c & 2)) { + /* If -u-x is a valid X coordinate, fail. */ + m = x; /* m = x */ + secp256k1_fe_add(&m, &u); /* m = u+x */ + secp256k1_fe_negate(&m, &m, 2); /* m = -u-x */ + if (secp256k1_ge_x_on_curve_var(&m)) return 0; /* test if -u-x on curve */ + + /* Let s = -(u^3 + 7)/(u^2 + u*x + x^2) [first part] */ + secp256k1_fe_sqr(&s, &m); /* s = (u+x)^2 */ + secp256k1_fe_negate(&s, &s, 1); /* s= -(u+x)^2 */ + secp256k1_fe_mul(&m, &u, &x); /* m = u*x */ + secp256k1_fe_add(&s, &m); /* s = -(u^2 + u*x + x^2) */ + + /* If s is not square, fail. We have not fully computed s yet, but s is square iff + * -(u^3+7)*(u^2+u*x+x^2) is square. */ + secp256k1_fe_sqr(&g, &u); /* g = u^2 */ + secp256k1_fe_mul(&g, &g, &u); /* g = u^3 */ + secp256k1_fe_add_int(&g, SECP256K1_B); /* g = u^3+7 */ + secp256k1_fe_mul(&m, &s, &g); /* m = -(u^3 + 7)*(u^2 + u*x + x^2) */ + if (!secp256k1_fe_is_square_var(&m)) return 0; + + /* Let s = -(u^3 + 7)/(u^2 + u*x + x^2) [second part] */ + secp256k1_fe_inv_var(&s, &s); /* s = -1/(u^2 + u*x + x^2) */ + secp256k1_fe_mul(&s, &s, &g); /* s = -(u^3 + 7)/(u^2 + u*x + x^2) */ + + /* Let v = x. */ + v = x; + } else { + /* Let s = x-u. */ + secp256k1_fe_negate(&m, &u, 1); /* m = -u */ + s = m; /* s = -u */ + secp256k1_fe_add(&s, &x); /* s = x-u */ + + /* If s=0, fail. */ + if (secp256k1_fe_normalizes_to_zero_var(&s)) return 0; + + /* If s is not square, fail. */ + if (!secp256k1_fe_is_square_var(&s)) return 0; + + /* Let r = sqrt(-s*(4*(u^3+7)+3*u^2*s)); fail if it doesn't exist. */ + secp256k1_fe_sqr(&u2, &u); /* u2 = u^2 */ + secp256k1_fe_mul(&g, &u2, &u); /* g = u^3 */ + secp256k1_fe_add_int(&g, SECP256K1_B); /* g = u^3+7 */ + secp256k1_fe_normalize_weak(&g); + secp256k1_fe_mul_int(&g, 4); /* g = 4*(u^3+7) */ + secp256k1_fe_mul_int(&u2, 3); /* u2 = 3*u^2 */ + secp256k1_fe_mul(&q, &s, &u2); /* q = 3*s*u^2 */ + secp256k1_fe_add(&q, &g); /* q = 4*(u^3+7)+3*s*u^2 */ + secp256k1_fe_mul(&q, &q, &s); /* q = s*(4*(u^3+7)+3*u^2*s) */ + secp256k1_fe_negate(&q, &q, 1); /* q = -s*(4*(u^3+7)+3*u^2*s) */ + if (!secp256k1_fe_is_square_var(&q)) return 0; + VERIFY_CHECK(secp256k1_fe_sqrt(&r, &q)); /* r = sqrt(-s*(4*(u^3+7)+3*u^2*s)) */ + + /* If (c & 1) = 1 and r = 0, fail. */ + if ((c & 1) && secp256k1_fe_normalizes_to_zero_var(&r)) return 0; + + /* Let v=(r/s-u)/2. */ + secp256k1_fe_inv_var(&v, &s); /* v=1/s */ + secp256k1_fe_mul(&v, &v, &r); /* v=r/s */ + secp256k1_fe_add(&v, &m); /* v=r/s-u */ + secp256k1_fe_half(&v); /* v=(r/s-u)/2 */ + } + + /* Let w=sqrt(s). */ + VERIFY_CHECK(secp256k1_fe_sqrt(&m, &s)); /* m = sqrt(s) = w */ + + /* Return logic. */ + if ((c & 5) == 0 || (c & 5) == 5) { + secp256k1_fe_negate(&m, &m, 1); /* m = -w */ + } + /* Now m = {w if c&5=0 or c&5=5; -w otherwise}. */ + secp256k1_fe_mul(&u, &u, c&1 ? &secp256k1_ellswift_c4 : &secp256k1_ellswift_c3); + /* u = {c4 if c&1=1; c3 otherwise}*u */ + secp256k1_fe_add(&u, &v); /* u = {c4 if c&1=1; c3 otherwise}*u + v */ + secp256k1_fe_mul(t, &m, &u); + return 1; +} + +/** Find an ElligatorSwift encoding (u, t) for X coordinate x. + * + * hasher is a SHA256 object which a incrementing 4-byte counter is added to to + * generate randomness for the rejection sampling in this function. Its size plus + * 4 (for the counter) plus 9 (for the SHA256 padding) must be a multiple of 64 + * for efficiency reasons. + */ +static void secp256k1_ellswift_xelligatorswift_var(secp256k1_fe* u, secp256k1_fe* t, const secp256k1_fe* x, const secp256k1_sha256* hasher) { + /* Pool of 3-bit branch values. */ + unsigned char branch_hash[32]; + /* Number of 3-bit values in branch_hash left. */ + int branches_left = 0; + /* Field elements u and branch values are extracted from + * SHA256(hasher || cnt) for consecutive values of cnt. cnt==0 + * is first used to populate a pool of 64 4-bit branch values. The 64 cnt + * values that follow are used to generate field elements u. cnt==65 (and + * multiples thereof) are used to repopulate the pool and start over, if + * that were ever necessary. */ + uint32_t cnt = 0; + VERIFY_CHECK((hasher->bytes + 4 + 9) % 64 == 0); + while (1) { + int branch; + /* If the pool of branch values is empty, populate it. */ + if (branches_left == 0) { + secp256k1_sha256 hash = *hasher; + unsigned char buf4[4]; + buf4[0] = cnt; + buf4[1] = cnt >> 8; + buf4[2] = cnt >> 16; + buf4[3] = cnt >> 24; + ++cnt; + secp256k1_sha256_write(&hash, buf4, 4); + secp256k1_sha256_finalize(&hash, branch_hash); + branches_left = 64; + } + /* Take a 3-bit branch value from the branch pool (top bit is discarded). */ + --branches_left; + branch = (branch_hash[branches_left >> 1] >> ((branches_left & 1) << 2)) & 7; + /* Compute a new u value by hashing. */ + { + secp256k1_sha256 hash = *hasher; + unsigned char buf4[4]; + unsigned char u32[32]; + buf4[0] = cnt; + buf4[1] = cnt >> 8; + buf4[2] = cnt >> 16; + buf4[3] = cnt >> 24; + ++cnt; + secp256k1_sha256_write(&hash, buf4, 4); + secp256k1_sha256_finalize(&hash, u32); + if (!secp256k1_fe_set_b32(u, u32)) continue; + if (secp256k1_fe_is_zero(u)) continue; + } + /* Find a remainder t, and return it if found. */ + if (secp256k1_ellswift_xswiftec_inv_var(t, x, u, branch)) { + secp256k1_fe_normalize_var(t); + break; + } + } +} + +/** Find an ElligatorSwift encoding (u, t) for point P. */ +static void secp256k1_ellswift_elligatorswift_var(secp256k1_fe* u, secp256k1_fe* t, const secp256k1_ge* p, const secp256k1_sha256* hasher) { + secp256k1_ellswift_xelligatorswift_var(u, t, &p->x, hasher); + if (secp256k1_fe_is_odd(t) != secp256k1_fe_is_odd(&p->y)) { + secp256k1_fe_negate(t, t, 1); + secp256k1_fe_normalize_var(t); + } +} + +int secp256k1_ellswift_encode(const secp256k1_context* ctx, unsigned char *ell64, const secp256k1_pubkey *pubkey, const unsigned char *rnd32) { + secp256k1_ge p; + VERIFY_CHECK(ctx != NULL); + ARG_CHECK(ell64 != NULL); + ARG_CHECK(pubkey != NULL); + ARG_CHECK(rnd32 != NULL); + + if (secp256k1_pubkey_load(ctx, &p, pubkey)) { + static const unsigned char PREFIX[128 - 9 - 4 - 32 - 33] = "secp256k1_ellswift_encode"; + secp256k1_fe u, t; + unsigned char p33[33]; + secp256k1_sha256 hash; + + /* Set up hasher state */ + secp256k1_sha256_initialize(&hash); + secp256k1_sha256_write(&hash, PREFIX, sizeof(PREFIX)); + secp256k1_sha256_write(&hash, rnd32, 32); + secp256k1_fe_get_b32(p33, &p.x); + p33[32] = secp256k1_fe_is_odd(&p.y); + secp256k1_sha256_write(&hash, p33, sizeof(p33)); + VERIFY_CHECK(hash.bytes == 128 - 9 - 4); + + /* Compute ElligatorSwift encoding and construct output. */ + secp256k1_ellswift_elligatorswift_var(&u, &t, &p, &hash); + secp256k1_fe_get_b32(ell64, &u); + secp256k1_fe_get_b32(ell64 + 32, &t); + return 1; + } + /* Only returned in case the provided pubkey is invalid. */ + return 0; +} + +int secp256k1_ellswift_create(const secp256k1_context* ctx, unsigned char *ell64, const unsigned char *seckey32, const unsigned char *rnd32) { + secp256k1_ge p; + secp256k1_fe u, t; + secp256k1_sha256 hash; + secp256k1_scalar seckey_scalar; + static const unsigned char PREFIX[32] = "secp256k1_ellswift_create"; + static const unsigned char ZERO[32] = {0}; + int ret = 0; + + /* Sanity check inputs. */ + VERIFY_CHECK(ctx != NULL); + ARG_CHECK(ell64 != NULL); + memset(ell64, 0, 64); + ARG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx)); + ARG_CHECK(seckey32 != NULL); + + /* Compute (affine) public key */ + ret = secp256k1_ec_pubkey_create_helper(&ctx->ecmult_gen_ctx, &seckey_scalar, &p, seckey32); + secp256k1_declassify(ctx, &p, sizeof(p)); /* not constant time in produced pubkey */ + secp256k1_fe_normalize_var(&p.x); + secp256k1_fe_normalize_var(&p.y); + + /* Set up hasher state */ + secp256k1_sha256_initialize(&hash); + secp256k1_sha256_write(&hash, PREFIX, sizeof(PREFIX)); + secp256k1_sha256_write(&hash, seckey32, 32); + secp256k1_sha256_write(&hash, rnd32 ? rnd32 : ZERO, 32); + secp256k1_sha256_write(&hash, ZERO, 32 - 9 - 4); + secp256k1_declassify(ctx, &hash, sizeof(hash)); /* hasher gets to declassify private key */ + + /* Compute ElligatorSwift encoding and construct output. */ + secp256k1_ellswift_elligatorswift_var(&u, &t, &p, &hash); + secp256k1_fe_get_b32(ell64, &u); + secp256k1_fe_get_b32(ell64 + 32, &t); + + secp256k1_memczero(ell64, 64, !ret); + secp256k1_scalar_clear(&seckey_scalar); + + return ret; +} + +int secp256k1_ellswift_decode(const secp256k1_context* ctx, secp256k1_pubkey *pubkey, const unsigned char *ell64) { + secp256k1_fe u, t; + secp256k1_ge p; + VERIFY_CHECK(ctx != NULL); + ARG_CHECK(pubkey != NULL); + ARG_CHECK(ell64 != NULL); + + secp256k1_fe_set_b32(&u, ell64); + secp256k1_fe_normalize_var(&u); + secp256k1_fe_set_b32(&t, ell64 + 32); + secp256k1_fe_normalize_var(&t); + secp256k1_ellswift_swiftec_var(&p, &u, &t); + secp256k1_pubkey_save(pubkey, &p); + return 1; +} + +static int ellswift_xdh_hash_function_sha256(unsigned char *output, const unsigned char *x32, const unsigned char *ours64, const unsigned char *theirs64, void *data) { + secp256k1_sha256 sha; + + (void)data; + + secp256k1_sha256_initialize(&sha); + if (secp256k1_memcmp_var(ours64, theirs64, 64) <= 0) { + secp256k1_sha256_write(&sha, ours64, 64); + secp256k1_sha256_write(&sha, theirs64, 64); + } else { + secp256k1_sha256_write(&sha, theirs64, 64); + secp256k1_sha256_write(&sha, ours64, 64); + } + secp256k1_sha256_write(&sha, x32, 32); + secp256k1_sha256_finalize(&sha, output); + + return 1; +} + +const secp256k1_ellswift_xdh_hash_function secp256k1_ellswift_xdh_hash_function_sha256 = ellswift_xdh_hash_function_sha256; +const secp256k1_ellswift_xdh_hash_function secp256k1_ellswift_xdh_hash_function_default = ellswift_xdh_hash_function_sha256; + +int secp256k1_ellswift_xdh(const secp256k1_context* ctx, unsigned char *output, const unsigned char* theirs64, const unsigned char* ours64, const unsigned char* seckey32, secp256k1_ellswift_xdh_hash_function hashfp, void *data) { + int ret = 0; + int overflow; + secp256k1_scalar s; + secp256k1_fe xn, xd, px, u, t; + unsigned char sx[32]; + + VERIFY_CHECK(ctx != NULL); + ARG_CHECK(output != NULL); + ARG_CHECK(theirs64 != NULL); + ARG_CHECK(ours64 != NULL); + ARG_CHECK(seckey32 != NULL); + + if (hashfp == NULL) { + hashfp = secp256k1_ellswift_xdh_hash_function_default; + } + + /* Load remote public key (as fraction). */ + secp256k1_fe_set_b32(&u, theirs64); + secp256k1_fe_normalize_var(&u); + secp256k1_fe_set_b32(&t, theirs64 + 32); + secp256k1_fe_normalize_var(&t); + secp256k1_ellswift_xswiftec_frac_var(&xn, &xd, &u, &t); + + /* Load private key (using one if invalid). */ + secp256k1_scalar_set_b32(&s, seckey32, &overflow); + overflow = secp256k1_scalar_is_zero(&s); + secp256k1_scalar_cmov(&s, &secp256k1_scalar_one, overflow); + + /* Compute shared X coordinate. */ + secp256k1_ecmult_const_xonly(&px, &xn, &xd, &s, 256, 1); + secp256k1_fe_normalize(&px); + secp256k1_fe_get_b32(sx, &px); + + /* Invoke hasher */ + ret = hashfp(output, sx, ours64, theirs64, data); + + memset(sx, 0, 32); + secp256k1_fe_clear(&px); + secp256k1_scalar_clear(&s); + + return !!ret & !overflow; +} + +#endif diff --git a/src/modules/ellswift/tests_impl.h b/src/modules/ellswift/tests_impl.h new file mode 100644 index 0000000000000..c54d8558d61f2 --- /dev/null +++ b/src/modules/ellswift/tests_impl.h @@ -0,0 +1,292 @@ +/*********************************************************************** + * Copyright (c) 2022 Pieter Wuile * + * Distributed under the MIT software license, see the accompanying * + * file COPYING or https://www.opensource.org/licenses/mit-license.php.* + ***********************************************************************/ + +#ifndef SECP256K1_MODULE_ELLSWIFT_TESTS_H +#define SECP256K1_MODULE_ELLSWIFT_TESTS_H + +#include "../../../include/secp256k1_ellswift.h" + +struct ellswift_xswiftec_inv_test { + int enc_bitmap; + secp256k1_fe u; + secp256k1_fe x; + secp256k1_fe encs[8]; +}; + +struct ellswift_decode_test { + unsigned char enc[64]; + secp256k1_fe x; + int odd_y; +}; + +/* Set of (point, encodings) test vectors, selected to maximize branch coverage. + * Created using an independent implementation, and tested against paper author's code. */ +static const struct ellswift_xswiftec_inv_test ellswift_xswiftec_inv_tests[] = { + {0xcc, SECP256K1_FE_CONST(0x05ff6bda, 0xd900fc32, 0x61bc7fe3, 0x4e2fb0f5, 0x69f06e09, 0x1ae437d3, 0xa52e9da0, 0xcbfb9590), SECP256K1_FE_CONST(0x80cdf637, 0x74ec7022, 0xc89a5a85, 0x58e373a2, 0x79170285, 0xe0ab2741, 0x2dbce510, 0xbdfe23fc), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x45654798, 0xece071ba, 0x79286d04, 0xf7f3eb1c, 0x3f1d17dd, 0x883610f2, 0xad2efd82, 0xa287466b), SECP256K1_FE_CONST(0x0aeaa886, 0xf6b76c71, 0x58452418, 0xcbf5033a, 0xdc5747e9, 0xe9b5d3b2, 0x303db969, 0x36528557), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xba9ab867, 0x131f8e45, 0x86d792fb, 0x080c14e3, 0xc0e2e822, 0x77c9ef0d, 0x52d1027c, 0x5d78b5c4), SECP256K1_FE_CONST(0xf5155779, 0x0948938e, 0xa7badbe7, 0x340afcc5, 0x23a8b816, 0x164a2c4d, 0xcfc24695, 0xc9ad76d8)}}, + {0x33, SECP256K1_FE_CONST(0x1737a85f, 0x4c8d146c, 0xec96e3ff, 0xdca76d99, 0x03dcf3bd, 0x53061868, 0xd478c78c, 0x63c2aa9e), SECP256K1_FE_CONST(0x39e48dd1, 0x50d2f429, 0xbe088dfd, 0x5b61882e, 0x7e840748, 0x3702ae9a, 0x5ab35927, 0xb15f85ea), {SECP256K1_FE_CONST(0x1be8cc0b, 0x04be0c68, 0x1d0c6a68, 0xf733f82c, 0x6c896e0c, 0x8a262fcd, 0x392918e3, 0x03a7abf4), SECP256K1_FE_CONST(0x605b5814, 0xbf9b8cb0, 0x66667c9e, 0x5480d22d, 0xc5b6c92f, 0x14b4af3e, 0xe0a9eb83, 0xb03685e3), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xe41733f4, 0xfb41f397, 0xe2f39597, 0x08cc07d3, 0x937691f3, 0x75d9d032, 0xc6d6e71b, 0xfc58503b), SECP256K1_FE_CONST(0x9fa4a7eb, 0x4064734f, 0x99998361, 0xab7f2dd2, 0x3a4936d0, 0xeb4b50c1, 0x1f56147b, 0x4fc9764c), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0x00, SECP256K1_FE_CONST(0x1aaa1cce, 0xbf9c7241, 0x91033df3, 0x66b36f69, 0x1c4d902c, 0x228033ff, 0x4516d122, 0xb2564f68), SECP256K1_FE_CONST(0xc7554125, 0x9d3ba98f, 0x207eaa30, 0xc69634d1, 0x87d0b6da, 0x594e719e, 0x420f4898, 0x638fc5b0), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0x33, SECP256K1_FE_CONST(0x2323a1d0, 0x79b0fd72, 0xfc8bb62e, 0xc34230a8, 0x15cb0596, 0xc2bfac99, 0x8bd6b842, 0x60f5dc26), SECP256K1_FE_CONST(0x239342df, 0xb675500a, 0x34a19631, 0x0b8d87d5, 0x4f49dcac, 0x9da50c17, 0x43ceab41, 0xa7b249ff), {SECP256K1_FE_CONST(0xf63580b8, 0xaa49c484, 0x6de56e39, 0xe1b3e73f, 0x171e881e, 0xba8c66f6, 0x14e67e5c, 0x975dfc07), SECP256K1_FE_CONST(0xb6307b33, 0x2e699f1c, 0xf77841d9, 0x0af25365, 0x404deb7f, 0xed5edb30, 0x90db49e6, 0x42a156b6), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x09ca7f47, 0x55b63b7b, 0x921a91c6, 0x1e4c18c0, 0xe8e177e1, 0x45739909, 0xeb1981a2, 0x68a20028), SECP256K1_FE_CONST(0x49cf84cc, 0xd19660e3, 0x0887be26, 0xf50dac9a, 0xbfb21480, 0x12a124cf, 0x6f24b618, 0xbd5ea579), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0x33, SECP256K1_FE_CONST(0x2dc90e64, 0x0cb646ae, 0x9164c0b5, 0xa9ef0169, 0xfebe34dc, 0x4437d6e4, 0x6acb0e27, 0xe219d1e8), SECP256K1_FE_CONST(0xd236f19b, 0xf349b951, 0x6e9b3f4a, 0x5610fe96, 0x0141cb23, 0xbbc8291b, 0x9534f1d7, 0x1de62a47), {SECP256K1_FE_CONST(0xe69df7d9, 0xc026c366, 0x00ebdf58, 0x80726758, 0x47c0c431, 0xc8eb7306, 0x82533e96, 0x4b6252c9), SECP256K1_FE_CONST(0x4f18bbdf, 0x7c2d6c5f, 0x818c1880, 0x2fa35cd0, 0x69eaa79f, 0xff74e4fc, 0x837c80d9, 0x3fece2f8), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x19620826, 0x3fd93c99, 0xff1420a7, 0x7f8d98a7, 0xb83f3bce, 0x37148cf9, 0x7dacc168, 0xb49da966), SECP256K1_FE_CONST(0xb0e74420, 0x83d293a0, 0x7e73e77f, 0xd05ca32f, 0x96155860, 0x008b1b03, 0x7c837f25, 0xc0131937), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0xcc, SECP256K1_FE_CONST(0x3edd7b39, 0x80e2f2f3, 0x4d1409a2, 0x07069f88, 0x1fda5f96, 0xf08027ac, 0x4465b63d, 0xc278d672), SECP256K1_FE_CONST(0x053a98de, 0x4a27b196, 0x1155822b, 0x3a3121f0, 0x3b2a1445, 0x8bd80eb4, 0xa560c4c7, 0xa85c149c), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xb3dae4b7, 0xdcf858e4, 0xc6968057, 0xcef2b156, 0x46543152, 0x6538199c, 0xf52dc1b2, 0xd62fda30), SECP256K1_FE_CONST(0x4aa77dd5, 0x5d6b6d3c, 0xfa10cc9d, 0x0fe42f79, 0x232e4575, 0x661049ae, 0x36779c1d, 0x0c666d88), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x4c251b48, 0x2307a71b, 0x39697fa8, 0x310d4ea9, 0xb9abcead, 0x9ac7e663, 0x0ad23e4c, 0x29d021ff), SECP256K1_FE_CONST(0xb558822a, 0xa29492c3, 0x05ef3362, 0xf01bd086, 0xdcd1ba8a, 0x99efb651, 0xc98863e1, 0xf3998ea7)}}, + {0x00, SECP256K1_FE_CONST(0x4295737e, 0xfcb1da6f, 0xb1d96b9c, 0xa7dcd1e3, 0x20024b37, 0xa736c494, 0x8b625981, 0x73069f70), SECP256K1_FE_CONST(0xfa7ffe4f, 0x25f88362, 0x831c087a, 0xfe2e8a9b, 0x0713e2ca, 0xc1ddca6a, 0x383205a2, 0x66f14307), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0xff, SECP256K1_FE_CONST(0x587c1a0c, 0xee91939e, 0x7f784d23, 0xb963004a, 0x3bf44f5d, 0x4e32a008, 0x1995ba20, 0xb0fca59e), SECP256K1_FE_CONST(0x2ea98853, 0x0715e8d1, 0x0363907f, 0xf2512452, 0x4d471ba2, 0x454d5ce3, 0xbe3f0419, 0x4dfd3a3c), {SECP256K1_FE_CONST(0xcfd5a094, 0xaa0b9b88, 0x91b76c6a, 0xb9438f66, 0xaa1c095a, 0x65f9f701, 0x35e81712, 0x92245e74), SECP256K1_FE_CONST(0xa89057d7, 0xc6563f0d, 0x6efa19ae, 0x84412b8a, 0x7b47e791, 0xa191ecdf, 0xdf2af84f, 0xd97bc339), SECP256K1_FE_CONST(0x475d0ae9, 0xef46920d, 0xf07b3411, 0x7be5a081, 0x7de1023e, 0x3cc32689, 0xe9be145b, 0x406b0aef), SECP256K1_FE_CONST(0xa0759178, 0xad802324, 0x54f827ef, 0x05ea3e72, 0xad8d7541, 0x8e6d4cc1, 0xcd4f5306, 0xc5e7c453), SECP256K1_FE_CONST(0x302a5f6b, 0x55f46477, 0x6e489395, 0x46bc7099, 0x55e3f6a5, 0x9a0608fe, 0xca17e8ec, 0x6ddb9dbb), SECP256K1_FE_CONST(0x576fa828, 0x39a9c0f2, 0x9105e651, 0x7bbed475, 0x84b8186e, 0x5e6e1320, 0x20d507af, 0x268438f6), SECP256K1_FE_CONST(0xb8a2f516, 0x10b96df2, 0x0f84cbee, 0x841a5f7e, 0x821efdc1, 0xc33cd976, 0x1641eba3, 0xbf94f140), SECP256K1_FE_CONST(0x5f8a6e87, 0x527fdcdb, 0xab07d810, 0xfa15c18d, 0x52728abe, 0x7192b33e, 0x32b0acf8, 0x3a1837dc)}}, + {0xcc, SECP256K1_FE_CONST(0x5fa88b33, 0x65a635cb, 0xbcee003c, 0xce9ef51d, 0xd1a310de, 0x277e441a, 0xbccdb7be, 0x1e4ba249), SECP256K1_FE_CONST(0x79461ff6, 0x2bfcbcac, 0x4249ba84, 0xdd040f2c, 0xec3c63f7, 0x25204dc7, 0xf464c16b, 0xf0ff3170), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x6bb700e1, 0xf4d7e236, 0xe8d193ff, 0x4a76c1b3, 0xbcd4e2b2, 0x5acac3d5, 0x1c8dac65, 0x3fe909a0), SECP256K1_FE_CONST(0xf4c73410, 0x633da7f6, 0x3a4f1d55, 0xaec6dd32, 0xc4c6d89e, 0xe74075ed, 0xb5515ed9, 0x0da9e683), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x9448ff1e, 0x0b281dc9, 0x172e6c00, 0xb5893e4c, 0x432b1d4d, 0xa5353c2a, 0xe3725399, 0xc016f28f), SECP256K1_FE_CONST(0x0b38cbef, 0x9cc25809, 0xc5b0e2aa, 0x513922cd, 0x3b392761, 0x18bf8a12, 0x4aaea125, 0xf25615ac)}}, + {0xcc, SECP256K1_FE_CONST(0x6fb31c75, 0x31f03130, 0xb42b155b, 0x952779ef, 0xbb46087d, 0xd9807d24, 0x1a48eac6, 0x3c3d96d6), SECP256K1_FE_CONST(0x56f81be7, 0x53e8d4ae, 0x4940ea6f, 0x46f6ec9f, 0xda66a6f9, 0x6cc95f50, 0x6cb2b574, 0x90e94260), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x59059774, 0x795bdb7a, 0x837fbe11, 0x40a5fa59, 0x984f48af, 0x8df95d57, 0xdd6d1c05, 0x437dcec1), SECP256K1_FE_CONST(0x22a644db, 0x79376ad4, 0xe7b3a009, 0xe58b3f13, 0x137c54fd, 0xf911122c, 0xc93667c4, 0x7077d784), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xa6fa688b, 0x86a42485, 0x7c8041ee, 0xbf5a05a6, 0x67b0b750, 0x7206a2a8, 0x2292e3f9, 0xbc822d6e), SECP256K1_FE_CONST(0xdd59bb24, 0x86c8952b, 0x184c5ff6, 0x1a74c0ec, 0xec83ab02, 0x06eeedd3, 0x36c9983a, 0x8f8824ab)}}, + {0x00, SECP256K1_FE_CONST(0x704cd226, 0xe71cb682, 0x6a590e80, 0xdac90f2d, 0x2f5830f0, 0xfdf135a3, 0xeae3965b, 0xff25ff12), SECP256K1_FE_CONST(0x138e0afa, 0x68936ee6, 0x70bd2b8d, 0xb53aedbb, 0x7bea2a85, 0x97388b24, 0xd0518edd, 0x22ad66ec), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0x33, SECP256K1_FE_CONST(0x725e9147, 0x92cb8c89, 0x49e7e116, 0x8b7cdd8a, 0x8094c91c, 0x6ec2202c, 0xcd53a6a1, 0x8771edeb), SECP256K1_FE_CONST(0x8da16eb8, 0x6d347376, 0xb6181ee9, 0x74832275, 0x7f6b36e3, 0x913ddfd3, 0x32ac595d, 0x788e0e44), {SECP256K1_FE_CONST(0xdd357786, 0xb9f68733, 0x30391aa5, 0x62580965, 0x4e43116e, 0x82a5a5d8, 0x2ffd1d66, 0x24101fc4), SECP256K1_FE_CONST(0xa0b7efca, 0x01814594, 0xc59c9aae, 0x8e497001, 0x86ca5d95, 0xe88bcc80, 0x399044d9, 0xc2d8613d), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x22ca8879, 0x460978cc, 0xcfc6e55a, 0x9da7f69a, 0xb1bcee91, 0x7d5a5a27, 0xd002e298, 0xdbefdc6b), SECP256K1_FE_CONST(0x5f481035, 0xfe7eba6b, 0x3a636551, 0x71b68ffe, 0x7935a26a, 0x1774337f, 0xc66fbb25, 0x3d279af2), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0x00, SECP256K1_FE_CONST(0x78fe6b71, 0x7f2ea4a3, 0x2708d79c, 0x151bf503, 0xa5312a18, 0xc0963437, 0xe865cc6e, 0xd3f6ae97), SECP256K1_FE_CONST(0x8701948e, 0x80d15b5c, 0xd8f72863, 0xeae40afc, 0x5aced5e7, 0x3f69cbc8, 0x179a3390, 0x2c094d98), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0x44, SECP256K1_FE_CONST(0x7c37bb9c, 0x5061dc07, 0x413f11ac, 0xd5a34006, 0xe64c5c45, 0x7fdb9a43, 0x8f217255, 0xa961f50d), SECP256K1_FE_CONST(0x5c1a76b4, 0x4568eb59, 0xd6789a74, 0x42d9ed7c, 0xdc6226b7, 0x752b4ff8, 0xeaf8e1a9, 0x5736e507), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xb94d30cd, 0x7dbff60b, 0x64620c17, 0xca0fafaa, 0x40b3d1f5, 0x2d077a60, 0xa2e0cafd, 0x145086c2), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x46b2cf32, 0x824009f4, 0x9b9df3e8, 0x35f05055, 0xbf4c2e0a, 0xd2f8859f, 0x5d1f3501, 0xebaf756d), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0x00, SECP256K1_FE_CONST(0x82388888, 0x967f82a6, 0xb444438a, 0x7d44838e, 0x13c0d478, 0xb9ca060d, 0xa95a41fb, 0x94303de6), SECP256K1_FE_CONST(0x29e96541, 0x70628fec, 0x8b497289, 0x8b113cf9, 0x8807f460, 0x9274f4f3, 0x140d0674, 0x157c90a0), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0x33, SECP256K1_FE_CONST(0x91298f57, 0x70af7a27, 0xf0a47188, 0xd24c3b7b, 0xf98ab299, 0x0d84b0b8, 0x98507e3c, 0x561d6472), SECP256K1_FE_CONST(0x144f4ccb, 0xd9a74698, 0xa88cbf6f, 0xd00ad886, 0xd339d29e, 0xa19448f2, 0xc572cac0, 0xa07d5562), {SECP256K1_FE_CONST(0xe6a0ffa3, 0x807f09da, 0xdbe71e0f, 0x4be4725f, 0x2832e76c, 0xad8dc1d9, 0x43ce8393, 0x75eff248), SECP256K1_FE_CONST(0x837b8e68, 0xd4917544, 0x764ad090, 0x3cb11f86, 0x15d2823c, 0xefbb06d8, 0x9049dbab, 0xc69befda), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x195f005c, 0x7f80f625, 0x2418e1f0, 0xb41b8da0, 0xd7cd1893, 0x52723e26, 0xbc317c6b, 0x8a1009e7), SECP256K1_FE_CONST(0x7c847197, 0x2b6e8abb, 0x89b52f6f, 0xc34ee079, 0xea2d7dc3, 0x1044f927, 0x6fb62453, 0x39640c55), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0x00, SECP256K1_FE_CONST(0xb682f3d0, 0x3bbb5dee, 0x4f54b5eb, 0xfba931b4, 0xf52f6a19, 0x1e5c2f48, 0x3c73c66e, 0x9ace97e1), SECP256K1_FE_CONST(0x904717bf, 0x0bc0cb78, 0x73fcdc38, 0xaa97f19e, 0x3a626309, 0x72acff92, 0xb24cc6dd, 0xa197cb96), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0x77, SECP256K1_FE_CONST(0xc17ec69e, 0x665f0fb0, 0xdbab48d9, 0xc2f94d12, 0xec8a9d7e, 0xacb58084, 0x83309180, 0x1eb0b80b), SECP256K1_FE_CONST(0x147756e6, 0x6d96e31c, 0x426d3cc8, 0x5ed0c4cf, 0xbef6341d, 0xd8b28558, 0x5aa574ea, 0x0204b55e), {SECP256K1_FE_CONST(0x6f4aea43, 0x1a0043bd, 0xd03134d6, 0xd9159119, 0xce034b88, 0xc32e50e8, 0xe36c4ee4, 0x5eac7ae9), SECP256K1_FE_CONST(0xfd5be16d, 0x4ffa2690, 0x126c67c3, 0xef7cb9d2, 0x9b74d397, 0xc78b06b3, 0x605fda34, 0xdc9696a6), SECP256K1_FE_CONST(0x5e9c6079, 0x2a2f000e, 0x45c6250f, 0x296f875e, 0x174efc0e, 0x9703e628, 0x706103a9, 0xdd2d82c7), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x90b515bc, 0xe5ffbc42, 0x2fcecb29, 0x26ea6ee6, 0x31fcb477, 0x3cd1af17, 0x1c93b11a, 0xa1538146), SECP256K1_FE_CONST(0x02a41e92, 0xb005d96f, 0xed93983c, 0x1083462d, 0x648b2c68, 0x3874f94c, 0x9fa025ca, 0x23696589), SECP256K1_FE_CONST(0xa1639f86, 0xd5d0fff1, 0xba39daf0, 0xd69078a1, 0xe8b103f1, 0x68fc19d7, 0x8f9efc55, 0x22d27968), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0xcc, SECP256K1_FE_CONST(0xc25172fc, 0x3f29b6fc, 0x4a1155b8, 0x57523315, 0x5486b274, 0x64b74b8b, 0x260b499a, 0x3f53cb14), SECP256K1_FE_CONST(0x1ea9cbdb, 0x35cf6e03, 0x29aa31b0, 0xbb0a702a, 0x65123ed0, 0x08655a93, 0xb7dcd528, 0x0e52e1ab), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x7422edc7, 0x843136af, 0x0053bb88, 0x54448a82, 0x99994f9d, 0xdcefd3a9, 0xa92d4546, 0x2c59298a), SECP256K1_FE_CONST(0x78c7774a, 0x266f8b97, 0xea23d05d, 0x064f033c, 0x77319f92, 0x3f6b78bc, 0xe4e20bf0, 0x5fa5398d), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x8bdd1238, 0x7bcec950, 0xffac4477, 0xabbb757d, 0x6666b062, 0x23102c56, 0x56d2bab8, 0xd3a6d2a5), SECP256K1_FE_CONST(0x873888b5, 0xd9907468, 0x15dc2fa2, 0xf9b0fcc3, 0x88ce606d, 0xc0948743, 0x1b1df40e, 0xa05ac2a2)}}, + {0x00, SECP256K1_FE_CONST(0xcab6626f, 0x832a4b12, 0x80ba7add, 0x2fc5322f, 0xf011caed, 0xedf7ff4d, 0xb6735d50, 0x26dc0367), SECP256K1_FE_CONST(0x2b2bef08, 0x52c6f7c9, 0x5d72ac99, 0xa23802b8, 0x75029cd5, 0x73b248d1, 0xf1b3fc80, 0x33788eb6), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0x33, SECP256K1_FE_CONST(0xd8621b4f, 0xfc85b9ed, 0x56e99d8d, 0xd1dd24ae, 0xdcecb147, 0x63b861a1, 0x7112dc77, 0x1a104fd2), SECP256K1_FE_CONST(0x812cabe9, 0x72a22aa6, 0x7c7da0c9, 0x4d8a9362, 0x96eb9949, 0xd70c37cb, 0x2b248757, 0x4cb3ce58), {SECP256K1_FE_CONST(0xfbc5febc, 0x6fdbc9ae, 0x3eb88a93, 0xb982196e, 0x8b6275a6, 0xd5a73c17, 0x387e000c, 0x711bd0e3), SECP256K1_FE_CONST(0x8724c96b, 0xd4e5527f, 0x2dd195a5, 0x1c468d2d, 0x211ba2fa, 0xc7cbe0b4, 0xb3434253, 0x409fb42d), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x043a0143, 0x90243651, 0xc147756c, 0x467de691, 0x749d8a59, 0x2a58c3e8, 0xc781fff2, 0x8ee42b4c), SECP256K1_FE_CONST(0x78db3694, 0x2b1aad80, 0xd22e6a5a, 0xe3b972d2, 0xdee45d05, 0x38341f4b, 0x4cbcbdab, 0xbf604802), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0x00, SECP256K1_FE_CONST(0xda463164, 0xc6f4bf71, 0x29ee5f0e, 0xc00f65a6, 0x75a8adf1, 0xbd931b39, 0xb64806af, 0xdcda9a22), SECP256K1_FE_CONST(0x25b9ce9b, 0x390b408e, 0xd611a0f1, 0x3ff09a59, 0x8a57520e, 0x426ce4c6, 0x49b7f94f, 0x2325620d), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0xcc, SECP256K1_FE_CONST(0xdafc971e, 0x4a3a7b6d, 0xcfb42a08, 0xd9692d82, 0xad9e7838, 0x523fcbda, 0x1d4827e1, 0x4481ae2d), SECP256K1_FE_CONST(0x250368e1, 0xb5c58492, 0x304bd5f7, 0x2696d27d, 0x526187c7, 0xadc03425, 0xe2b7d81d, 0xbb7e4e02), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x370c28f1, 0xbe665efa, 0xcde6aa43, 0x6bf86fe2, 0x1e6e314c, 0x1e53dd04, 0x0e6c73a4, 0x6b4c8c49), SECP256K1_FE_CONST(0xcd8acee9, 0x8ffe5653, 0x1a84d7eb, 0x3e48fa40, 0x34206ce8, 0x25ace907, 0xd0edf0ea, 0xeb5e9ca2), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xc8f3d70e, 0x4199a105, 0x321955bc, 0x9407901d, 0xe191ceb3, 0xe1ac22fb, 0xf1938c5a, 0x94b36fe6), SECP256K1_FE_CONST(0x32753116, 0x7001a9ac, 0xe57b2814, 0xc1b705bf, 0xcbdf9317, 0xda5316f8, 0x2f120f14, 0x14a15f8d)}}, + {0x44, SECP256K1_FE_CONST(0xe0294c8b, 0xc1a36b41, 0x66ee92bf, 0xa70a5c34, 0x976fa982, 0x9405efea, 0x8f9cd54d, 0xcb29b99e), SECP256K1_FE_CONST(0xae9690d1, 0x3b8d20a0, 0xfbbf37be, 0xd8474f67, 0xa04e142f, 0x56efd787, 0x70a76b35, 0x9165d8a1), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xdcd45d93, 0x5613916a, 0xf167b029, 0x058ba3a7, 0x00d37150, 0xb9df3472, 0x8cb05412, 0xc16d4182), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x232ba26c, 0xa9ec6e95, 0x0e984fd6, 0xfa745c58, 0xff2c8eaf, 0x4620cb8d, 0x734fabec, 0x3e92baad), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0x00, SECP256K1_FE_CONST(0xe148441c, 0xd7b92b8b, 0x0e4fa3bd, 0x68712cfd, 0x0d709ad1, 0x98cace61, 0x1493c10e, 0x97f5394e), SECP256K1_FE_CONST(0x164a6397, 0x94d74c53, 0xafc4d329, 0x4e79cdb3, 0xcd25f99f, 0x6df45c00, 0x0f758aba, 0x54d699c0), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0xff, SECP256K1_FE_CONST(0xe4b00ec9, 0x7aadcca9, 0x7644d3b0, 0xc8a931b1, 0x4ce7bcf7, 0xbc877954, 0x6d6e35aa, 0x5937381c), SECP256K1_FE_CONST(0x94e9588d, 0x41647b3f, 0xcc772dc8, 0xd83c67ce, 0x3be00353, 0x8517c834, 0x103d2cd4, 0x9d62ef4d), {SECP256K1_FE_CONST(0xc88d25f4, 0x1407376b, 0xb2c03a7f, 0xffeb3ec7, 0x811cc434, 0x91a0c3aa, 0xc0378cdc, 0x78357bee), SECP256K1_FE_CONST(0x51c02636, 0xce00c234, 0x5ecd89ad, 0xb6089fe4, 0xd5e18ac9, 0x24e3145e, 0x6669501c, 0xd37a00d4), SECP256K1_FE_CONST(0x205b3512, 0xdb40521c, 0xb200952e, 0x67b46f67, 0xe09e7839, 0xe0de4400, 0x4138329e, 0xbd9138c5), SECP256K1_FE_CONST(0x58aab390, 0xab6fb55c, 0x1d1b8089, 0x7a207ce9, 0x4a78fa5b, 0x4aa61a33, 0x398bcae9, 0xadb20d3e), SECP256K1_FE_CONST(0x3772da0b, 0xebf8c894, 0x4d3fc580, 0x0014c138, 0x7ee33bcb, 0x6e5f3c55, 0x3fc87322, 0x87ca8041), SECP256K1_FE_CONST(0xae3fd9c9, 0x31ff3dcb, 0xa1327652, 0x49f7601b, 0x2a1e7536, 0xdb1ceba1, 0x9996afe2, 0x2c85fb5b), SECP256K1_FE_CONST(0xdfa4caed, 0x24bfade3, 0x4dff6ad1, 0x984b9098, 0x1f6187c6, 0x1f21bbff, 0xbec7cd60, 0x426ec36a), SECP256K1_FE_CONST(0xa7554c6f, 0x54904aa3, 0xe2e47f76, 0x85df8316, 0xb58705a4, 0xb559e5cc, 0xc6743515, 0x524deef1)}}, + {0x00, SECP256K1_FE_CONST(0xe5bbb9ef, 0x360d0a50, 0x1618f006, 0x7d36dceb, 0x75f5be9a, 0x620232aa, 0x9fd5139d, 0x0863fde5), SECP256K1_FE_CONST(0xe5bbb9ef, 0x360d0a50, 0x1618f006, 0x7d36dceb, 0x75f5be9a, 0x620232aa, 0x9fd5139d, 0x0863fde5), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0xff, SECP256K1_FE_CONST(0xe6bcb5c3, 0xd63467d4, 0x90bfa54f, 0xbbc6092a, 0x7248c25e, 0x11b248dc, 0x2964a6e1, 0x5edb1457), SECP256K1_FE_CONST(0x19434a3c, 0x29cb982b, 0x6f405ab0, 0x4439f6d5, 0x8db73da1, 0xee4db723, 0xd69b591d, 0xa124e7d8), {SECP256K1_FE_CONST(0x67119877, 0x832ab8f4, 0x59a82165, 0x6d8261f5, 0x44a553b8, 0x9ae4f25c, 0x52a97134, 0xb70f3426), SECP256K1_FE_CONST(0xffee02f5, 0xe649c07f, 0x0560eff1, 0x867ec7b3, 0x2d0e595e, 0x9b1c0ea6, 0xe2a4fc70, 0xc97cd71f), SECP256K1_FE_CONST(0xb5e0c189, 0xeb5b4bac, 0xd025b744, 0x4d74178b, 0xe8d5246c, 0xfa4a9a20, 0x7964a057, 0xee969992), SECP256K1_FE_CONST(0x5746e459, 0x1bf7f4c3, 0x044609ea, 0x372e9086, 0x03975d27, 0x9fdef834, 0x9f0b08d3, 0x2f07619d), SECP256K1_FE_CONST(0x98ee6788, 0x7cd5470b, 0xa657de9a, 0x927d9e0a, 0xbb5aac47, 0x651b0da3, 0xad568eca, 0x48f0c809), SECP256K1_FE_CONST(0x0011fd0a, 0x19b63f80, 0xfa9f100e, 0x7981384c, 0xd2f1a6a1, 0x64e3f159, 0x1d5b038e, 0x36832510), SECP256K1_FE_CONST(0x4a1f3e76, 0x14a4b453, 0x2fda48bb, 0xb28be874, 0x172adb93, 0x05b565df, 0x869b5fa7, 0x1169629d), SECP256K1_FE_CONST(0xa8b91ba6, 0xe4080b3c, 0xfbb9f615, 0xc8d16f79, 0xfc68a2d8, 0x602107cb, 0x60f4f72b, 0xd0f89a92)}}, + {0x33, SECP256K1_FE_CONST(0xf28fba64, 0xaf766845, 0xeb2f4302, 0x456e2b9f, 0x8d80affe, 0x57e7aae4, 0x2738d7cd, 0xdb1c2ce6), SECP256K1_FE_CONST(0xf28fba64, 0xaf766845, 0xeb2f4302, 0x456e2b9f, 0x8d80affe, 0x57e7aae4, 0x2738d7cd, 0xdb1c2ce6), {SECP256K1_FE_CONST(0x4f867ad8, 0xbb3d8404, 0x09d26b67, 0x307e6210, 0x0153273f, 0x72fa4b74, 0x84becfa1, 0x4ebe7408), SECP256K1_FE_CONST(0x5bbc4f59, 0xe452cc5f, 0x22a99144, 0xb10ce898, 0x9a89a995, 0xec3cea1c, 0x91ae10e8, 0xf721bb5d), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xb0798527, 0x44c27bfb, 0xf62d9498, 0xcf819def, 0xfeacd8c0, 0x8d05b48b, 0x7b41305d, 0xb1418827), SECP256K1_FE_CONST(0xa443b0a6, 0x1bad33a0, 0xdd566ebb, 0x4ef31767, 0x6576566a, 0x13c315e3, 0x6e51ef16, 0x08de40d2), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, + {0xcc, SECP256K1_FE_CONST(0xf455605b, 0xc85bf48e, 0x3a908c31, 0x023faf98, 0x381504c6, 0xc6d3aeb9, 0xede55f8d, 0xd528924d), SECP256K1_FE_CONST(0xd31fbcd5, 0xcdb798f6, 0xc00db669, 0x2f8fe896, 0x7fa9c79d, 0xd10958f4, 0xa194f013, 0x74905e99), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0x0c00c571, 0x5b56fe63, 0x2d814ad8, 0xa77f8e66, 0x628ea47a, 0x6116834f, 0x8c1218f3, 0xa03cbd50), SECP256K1_FE_CONST(0xdf88e44f, 0xac84fa52, 0xdf4d59f4, 0x8819f18f, 0x6a8cd415, 0x1d162afa, 0xf773166f, 0x57c7ff46), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0xf3ff3a8e, 0xa4a9019c, 0xd27eb527, 0x58807199, 0x9d715b85, 0x9ee97cb0, 0x73ede70b, 0x5fc33edf), SECP256K1_FE_CONST(0x20771bb0, 0x537b05ad, 0x20b2a60b, 0x77e60e70, 0x95732bea, 0xe2e9d505, 0x088ce98f, 0xa837fce9)}}, + {0xff, SECP256K1_FE_CONST(0xf58cd4d9, 0x830bad32, 0x2699035e, 0x8246007d, 0x4be27e19, 0xb6f53621, 0x317b4f30, 0x9b3daa9d), SECP256K1_FE_CONST(0x78ec2b3d, 0xc0948de5, 0x60148bbc, 0x7c6dc963, 0x3ad5df70, 0xa5a5750c, 0xbed72180, 0x4f082a3b), {SECP256K1_FE_CONST(0x6c4c580b, 0x76c75940, 0x43569f9d, 0xae16dc28, 0x01c16a1f, 0xbe128608, 0x81b75f8e, 0xf929bce5), SECP256K1_FE_CONST(0x94231355, 0xe7385c5f, 0x25ca436a, 0xa6419147, 0x1aea4393, 0xd6e86ab7, 0xa35fe2af, 0xacaefd0d), SECP256K1_FE_CONST(0xdff2a195, 0x1ada6db5, 0x74df8340, 0x48149da3, 0x397a75b8, 0x29abf58c, 0x7e69db1b, 0x41ac0989), SECP256K1_FE_CONST(0xa52b66d3, 0xc9070355, 0x48028bf8, 0x04711bf4, 0x22aba95f, 0x1a666fc8, 0x6f4648e0, 0x5f29caae), SECP256K1_FE_CONST(0x93b3a7f4, 0x8938a6bf, 0xbca96062, 0x51e923d7, 0xfe3e95e0, 0x41ed79f7, 0x7e48a070, 0x06d63f4a), SECP256K1_FE_CONST(0x6bdcecaa, 0x18c7a3a0, 0xda35bc95, 0x59be6eb8, 0xe515bc6c, 0x29179548, 0x5ca01d4f, 0x5350ff22), SECP256K1_FE_CONST(0x200d5e6a, 0xe525924a, 0x8b207cbf, 0xb7eb625c, 0xc6858a47, 0xd6540a73, 0x819624e3, 0xbe53f2a6), SECP256K1_FE_CONST(0x5ad4992c, 0x36f8fcaa, 0xb7fd7407, 0xfb8ee40b, 0xdd5456a0, 0xe5999037, 0x90b9b71e, 0xa0d63181)}}, + {0x00, SECP256K1_FE_CONST(0xfd7d912a, 0x40f182a3, 0x588800d6, 0x9ebfb504, 0x8766da20, 0x6fd7ebc8, 0xd2436c81, 0xcbef6421), SECP256K1_FE_CONST(0x8d37c862, 0x054debe7, 0x31694536, 0xff46b273, 0xec122b35, 0xa9bf1445, 0xac3c4ff9, 0xf262c952), {SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0), SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 0)}}, +}; + +/* Set of (encoding, xcoord) test vectors, selected to maximize branch coverage. + * Created using an independent implementation, and tested against paper author's code. */ +static const struct ellswift_decode_test ellswift_decode_tests[] = { + {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0xedd1fd3e, 0x327ce90c, 0xc7a35426, 0x14289aee, 0x9682003e, 0x9cf7dcc9, 0xcf2ca974, 0x3be5aa0c), 0}, + {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0xd3, 0x47, 0x5b, 0xf7, 0x65, 0x5b, 0x0f, 0xb2, 0xd8, 0x52, 0x92, 0x10, 0x35, 0xb2, 0xef, 0x60, 0x7f, 0x49, 0x06, 0x9b, 0x97, 0x45, 0x4e, 0x67, 0x95, 0x25, 0x10, 0x62, 0x74, 0x17, 0x71}, SECP256K1_FE_CONST(0xb5da00b7, 0x3cd65605, 0x20e7c364, 0x086e7cd2, 0x3a34bf60, 0xd0e707be, 0x9fc34d4c, 0xd5fdfa2c), 1}, + {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x82, 0x27, 0x7c, 0x4a, 0x71, 0xf9, 0xd2, 0x2e, 0x66, 0xec, 0xe5, 0x23, 0xf8, 0xfa, 0x08, 0x74, 0x1a, 0x7c, 0x09, 0x12, 0xc6, 0x6a, 0x69, 0xce, 0x68, 0x51, 0x4b, 0xfd, 0x35, 0x15, 0xb4, 0x9f}, SECP256K1_FE_CONST(0xf482f2e2, 0x41753ad0, 0xfb89150d, 0x8491dc1e, 0x34ff0b8a, 0xcfbb442c, 0xfe999e2e, 0x5e6fd1d2), 1}, + {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x84, 0x21, 0xcc, 0x93, 0x0e, 0x77, 0xc9, 0xf5, 0x14, 0xb6, 0x91, 0x5c, 0x3d, 0xbe, 0x2a, 0x94, 0xc6, 0xd8, 0xf6, 0x90, 0xb5, 0xb7, 0x39, 0x86, 0x4b, 0xa6, 0x78, 0x9f, 0xb8, 0xa5, 0x5d, 0xd0}, SECP256K1_FE_CONST(0x9f59c402, 0x75f5085a, 0x006f05da, 0xe77eb98c, 0x6fd0db1a, 0xb4a72ac4, 0x7eae90a4, 0xfc9e57e0), 0}, + {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xbd, 0xe7, 0x0d, 0xf5, 0x19, 0x39, 0xb9, 0x4c, 0x9c, 0x24, 0x97, 0x9f, 0xa7, 0xdd, 0x04, 0xeb, 0xd9, 0xb3, 0x57, 0x2d, 0xa7, 0x80, 0x22, 0x90, 0x43, 0x8a, 0xf2, 0xa6, 0x81, 0x89, 0x54, 0x41}, SECP256K1_FE_CONST(0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaa9, 0xfffffd6b), 1}, + {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xd1, 0x9c, 0x18, 0x2d, 0x27, 0x59, 0xcd, 0x99, 0x82, 0x42, 0x28, 0xd9, 0x47, 0x99, 0xf8, 0xc6, 0x55, 0x7c, 0x38, 0xa1, 0xc0, 0xd6, 0x77, 0x9b, 0x9d, 0x4b, 0x72, 0x9c, 0x6f, 0x1c, 0xcc, 0x42}, SECP256K1_FE_CONST(0x70720db7, 0xe238d041, 0x21f5b1af, 0xd8cc5ad9, 0xd18944c6, 0xbdc94881, 0xf502b7a3, 0xaf3aecff), 0}, + {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0xedd1fd3e, 0x327ce90c, 0xc7a35426, 0x14289aee, 0x9682003e, 0x9cf7dcc9, 0xcf2ca974, 0x3be5aa0c), 0}, + {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x26, 0x64, 0xbb, 0xd5}, SECP256K1_FE_CONST(0x50873db3, 0x1badcc71, 0x890e4f67, 0x753a6575, 0x7f97aaa7, 0xdd5f1e82, 0xb753ace3, 0x2219064b), 0}, + {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x70, 0x28, 0xde, 0x7d}, SECP256K1_FE_CONST(0x1eea9cc5, 0x9cfcf2fa, 0x151ac6c2, 0x74eea411, 0x0feb4f7b, 0x68c59657, 0x32e9992e, 0x976ef68e), 0}, + {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xcb, 0xcf, 0xb7, 0xe7}, SECP256K1_FE_CONST(0x12303941, 0xaedc2088, 0x80735b1f, 0x1795c8e5, 0x5be520ea, 0x93e10335, 0x7b5d2adb, 0x7ed59b8e), 0}, + {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf3, 0x11, 0x3a, 0xd9}, SECP256K1_FE_CONST(0x7eed6b70, 0xe7b0767c, 0x7d7feac0, 0x4e57aa2a, 0x12fef5e0, 0xf48f878f, 0xcbb88b3b, 0x6b5e0783), 0}, + {{0x0a, 0x2d, 0x2b, 0xa9, 0x35, 0x07, 0xf1, 0xdf, 0x23, 0x37, 0x70, 0xc2, 0xa7, 0x97, 0x96, 0x2c, 0xc6, 0x1f, 0x6d, 0x15, 0xda, 0x14, 0xec, 0xd4, 0x7d, 0x8d, 0x27, 0xae, 0x1c, 0xd5, 0xf8, 0x53, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x532167c1, 0x1200b08c, 0x0e84a354, 0xe74dcc40, 0xf8b25f4f, 0xe686e308, 0x69526366, 0x278a0688), 0}, + {{0x0a, 0x2d, 0x2b, 0xa9, 0x35, 0x07, 0xf1, 0xdf, 0x23, 0x37, 0x70, 0xc2, 0xa7, 0x97, 0x96, 0x2c, 0xc6, 0x1f, 0x6d, 0x15, 0xda, 0x14, 0xec, 0xd4, 0x7d, 0x8d, 0x27, 0xae, 0x1c, 0xd5, 0xf8, 0x53, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x532167c1, 0x1200b08c, 0x0e84a354, 0xe74dcc40, 0xf8b25f4f, 0xe686e308, 0x69526366, 0x278a0688), 0}, + {{0x0f, 0xfd, 0xe9, 0xca, 0x81, 0xd7, 0x51, 0xe9, 0xcd, 0xaf, 0xfc, 0x1a, 0x50, 0x77, 0x92, 0x45, 0x32, 0x0b, 0x28, 0x99, 0x6d, 0xba, 0xf3, 0x2f, 0x82, 0x2f, 0x20, 0x11, 0x7c, 0x22, 0xfb, 0xd6, 0xc7, 0x4d, 0x99, 0xef, 0xce, 0xaa, 0x55, 0x0f, 0x1a, 0xd1, 0xc0, 0xf4, 0x3f, 0x46, 0xe7, 0xff, 0x1e, 0xe3, 0xbd, 0x01, 0x62, 0xb7, 0xbf, 0x55, 0xf2, 0x96, 0x5d, 0xa9, 0xc3, 0x45, 0x06, 0x46}, SECP256K1_FE_CONST(0x74e880b3, 0xffd18fe3, 0xcddf7902, 0x522551dd, 0xf97fa4a3, 0x5a3cfda8, 0x197f9470, 0x81a57b8f), 0}, + {{0x0f, 0xfd, 0xe9, 0xca, 0x81, 0xd7, 0x51, 0xe9, 0xcd, 0xaf, 0xfc, 0x1a, 0x50, 0x77, 0x92, 0x45, 0x32, 0x0b, 0x28, 0x99, 0x6d, 0xba, 0xf3, 0x2f, 0x82, 0x2f, 0x20, 0x11, 0x7c, 0x22, 0xfb, 0xd6, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x15, 0x6c, 0xa8, 0x96}, SECP256K1_FE_CONST(0x377b643f, 0xce2271f6, 0x4e5c8101, 0x566107c1, 0xbe498074, 0x50917838, 0x04f65478, 0x1ac9217c), 1}, + {{0x12, 0x36, 0x58, 0x44, 0x4f, 0x32, 0xbe, 0x8f, 0x02, 0xea, 0x20, 0x34, 0xaf, 0xa7, 0xef, 0x4b, 0xbe, 0x8a, 0xdc, 0x91, 0x8c, 0xeb, 0x49, 0xb1, 0x27, 0x73, 0xb6, 0x25, 0xf4, 0x90, 0xb3, 0x68, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x8d, 0xc5, 0xfe, 0x11}, SECP256K1_FE_CONST(0xed16d65c, 0xf3a9538f, 0xcb2c139f, 0x1ecbc143, 0xee148271, 0x20cbc265, 0x9e667256, 0x800b8142), 0}, + {{0x14, 0x6f, 0x92, 0x46, 0x4d, 0x15, 0xd3, 0x6e, 0x35, 0x38, 0x2b, 0xd3, 0xca, 0x5b, 0x0f, 0x97, 0x6c, 0x95, 0xcb, 0x08, 0xac, 0xdc, 0xf2, 0xd5, 0xb3, 0x57, 0x06, 0x17, 0x99, 0x08, 0x39, 0xd7, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x31, 0x45, 0xe9, 0x3b}, SECP256K1_FE_CONST(0x0d5cd840, 0x427f941f, 0x65193079, 0xab8e2e83, 0x024ef2ee, 0x7ca558d8, 0x8879ffd8, 0x79fb6657), 0}, + {{0x15, 0xfd, 0xf5, 0xcf, 0x09, 0xc9, 0x07, 0x59, 0xad, 0xd2, 0x27, 0x2d, 0x57, 0x4d, 0x2b, 0xb5, 0xfe, 0x14, 0x29, 0xf9, 0xf3, 0xc1, 0x4c, 0x65, 0xe3, 0x19, 0x4b, 0xf6, 0x1b, 0x82, 0xaa, 0x73, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x04, 0xcf, 0xd9, 0x06}, SECP256K1_FE_CONST(0x16d0e439, 0x46aec93f, 0x62d57eb8, 0xcde68951, 0xaf136cf4, 0xb307938d, 0xd1447411, 0xe07bffe1), 1}, + {{0x1f, 0x67, 0xed, 0xf7, 0x79, 0xa8, 0xa6, 0x49, 0xd6, 0xde, 0xf6, 0x00, 0x35, 0xf2, 0xfa, 0x22, 0xd0, 0x22, 0xdd, 0x35, 0x90, 0x79, 0xa1, 0xa1, 0x44, 0x07, 0x3d, 0x84, 0xf1, 0x9b, 0x92, 0xd5, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x025661f9, 0xaba9d15c, 0x3118456b, 0xbe980e3e, 0x1b8ba2e0, 0x47c737a4, 0xeb48a040, 0xbb566f6c), 0}, + {{0x1f, 0x67, 0xed, 0xf7, 0x79, 0xa8, 0xa6, 0x49, 0xd6, 0xde, 0xf6, 0x00, 0x35, 0xf2, 0xfa, 0x22, 0xd0, 0x22, 0xdd, 0x35, 0x90, 0x79, 0xa1, 0xa1, 0x44, 0x07, 0x3d, 0x84, 0xf1, 0x9b, 0x92, 0xd5, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x025661f9, 0xaba9d15c, 0x3118456b, 0xbe980e3e, 0x1b8ba2e0, 0x47c737a4, 0xeb48a040, 0xbb566f6c), 0}, + {{0x1f, 0xe1, 0xe5, 0xef, 0x3f, 0xce, 0xb5, 0xc1, 0x35, 0xab, 0x77, 0x41, 0x33, 0x3c, 0xe5, 0xa6, 0xe8, 0x0d, 0x68, 0x16, 0x76, 0x53, 0xf6, 0xb2, 0xb2, 0x4b, 0xcb, 0xcf, 0xaa, 0xaf, 0xf5, 0x07, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x98bec3b2, 0xa351fa96, 0xcfd191c1, 0x77835193, 0x1b9e9ba9, 0xad1149f6, 0xd9eadca8, 0x0981b801), 0}, + {{0x40, 0x56, 0xa3, 0x4a, 0x21, 0x0e, 0xec, 0x78, 0x92, 0xe8, 0x82, 0x06, 0x75, 0xc8, 0x60, 0x09, 0x9f, 0x85, 0x7b, 0x26, 0xaa, 0xd8, 0x54, 0x70, 0xee, 0x6d, 0x3c, 0xf1, 0x30, 0x4a, 0x9d, 0xcf, 0x37, 0x5e, 0x70, 0x37, 0x42, 0x71, 0xf2, 0x0b, 0x13, 0xc9, 0x98, 0x6e, 0xd7, 0xd3, 0xc1, 0x77, 0x99, 0x69, 0x8c, 0xfc, 0x43, 0x5d, 0xbe, 0xd3, 0xa9, 0xf3, 0x4b, 0x38, 0xc8, 0x23, 0xc2, 0xb4}, SECP256K1_FE_CONST(0x868aac20, 0x03b29dbc, 0xad1a3e80, 0x3855e078, 0xa89d1654, 0x3ac64392, 0xd1224172, 0x98cec76e), 0}, + {{0x41, 0x97, 0xec, 0x37, 0x23, 0xc6, 0x54, 0xcf, 0xdd, 0x32, 0xab, 0x07, 0x55, 0x06, 0x64, 0x8b, 0x2f, 0xf5, 0x07, 0x03, 0x62, 0xd0, 0x1a, 0x4f, 0xff, 0x14, 0xb3, 0x36, 0xb7, 0x8f, 0x96, 0x3f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xb3, 0xab, 0x1e, 0x95}, SECP256K1_FE_CONST(0xba5a6314, 0x502a8952, 0xb8f456e0, 0x85928105, 0xf665377a, 0x8ce27726, 0xa5b0eb7e, 0xc1ac0286), 0}, + {{0x47, 0xeb, 0x3e, 0x20, 0x8f, 0xed, 0xcd, 0xf8, 0x23, 0x4c, 0x94, 0x21, 0xe9, 0xcd, 0x9a, 0x7a, 0xe8, 0x73, 0xbf, 0xbd, 0xbc, 0x39, 0x37, 0x23, 0xd1, 0xba, 0x1e, 0x1e, 0x6a, 0x8e, 0x6b, 0x24, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7c, 0xd1, 0x2c, 0xb1}, SECP256K1_FE_CONST(0xd192d520, 0x07e541c9, 0x807006ed, 0x0468df77, 0xfd214af0, 0xa795fe11, 0x9359666f, 0xdcf08f7c), 0}, + {{0x5e, 0xb9, 0x69, 0x6a, 0x23, 0x36, 0xfe, 0x2c, 0x3c, 0x66, 0x6b, 0x02, 0xc7, 0x55, 0xdb, 0x4c, 0x0c, 0xfd, 0x62, 0x82, 0x5c, 0x7b, 0x58, 0x9a, 0x7b, 0x7b, 0xb4, 0x42, 0xe1, 0x41, 0xc1, 0xd6, 0x93, 0x41, 0x3f, 0x00, 0x52, 0xd4, 0x9e, 0x64, 0xab, 0xec, 0x6d, 0x58, 0x31, 0xd6, 0x6c, 0x43, 0x61, 0x28, 0x30, 0xa1, 0x7d, 0xf1, 0xfe, 0x43, 0x83, 0xdb, 0x89, 0x64, 0x68, 0x10, 0x02, 0x21}, SECP256K1_FE_CONST(0xef6e1da6, 0xd6c7627e, 0x80f7a723, 0x4cb08a02, 0x2c1ee1cf, 0x29e4d0f9, 0x642ae924, 0xcef9eb38), 1}, + {{0x7b, 0xf9, 0x6b, 0x7b, 0x6d, 0xa1, 0x5d, 0x34, 0x76, 0xa2, 0xb1, 0x95, 0x93, 0x4b, 0x69, 0x0a, 0x3a, 0x3d, 0xe3, 0xe8, 0xab, 0x84, 0x74, 0x85, 0x68, 0x63, 0xb0, 0xde, 0x3a, 0xf9, 0x0b, 0x0e, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x50851dfc, 0x9f418c31, 0x4a437295, 0xb24feeea, 0x27af3d0c, 0xd2308348, 0xfda6e21c, 0x463e46ff), 0}, + {{0x7b, 0xf9, 0x6b, 0x7b, 0x6d, 0xa1, 0x5d, 0x34, 0x76, 0xa2, 0xb1, 0x95, 0x93, 0x4b, 0x69, 0x0a, 0x3a, 0x3d, 0xe3, 0xe8, 0xab, 0x84, 0x74, 0x85, 0x68, 0x63, 0xb0, 0xde, 0x3a, 0xf9, 0x0b, 0x0e, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x50851dfc, 0x9f418c31, 0x4a437295, 0xb24feeea, 0x27af3d0c, 0xd2308348, 0xfda6e21c, 0x463e46ff), 0}, + {{0x85, 0x1b, 0x1c, 0xa9, 0x45, 0x49, 0x37, 0x1c, 0x4f, 0x1f, 0x71, 0x87, 0x32, 0x1d, 0x39, 0xbf, 0x51, 0xc6, 0xb7, 0xfb, 0x61, 0xf7, 0xcb, 0xf0, 0x27, 0xc9, 0xda, 0x62, 0x02, 0x1b, 0x7a, 0x65, 0xfc, 0x54, 0xc9, 0x68, 0x37, 0xfb, 0x22, 0xb3, 0x62, 0xed, 0xa6, 0x3e, 0xc5, 0x2e, 0xc8, 0x3d, 0x81, 0xbe, 0xdd, 0x16, 0x0c, 0x11, 0xb2, 0x2d, 0x96, 0x5d, 0x9f, 0x4a, 0x6d, 0x64, 0xd2, 0x51}, SECP256K1_FE_CONST(0x3e731051, 0xe12d3323, 0x7eb324f2, 0xaa5b16bb, 0x868eb49a, 0x1aa1fadc, 0x19b6e876, 0x1b5a5f7b), 1}, + {{0x94, 0x3c, 0x2f, 0x77, 0x51, 0x08, 0xb7, 0x37, 0xfe, 0x65, 0xa9, 0x53, 0x1e, 0x19, 0xf2, 0xfc, 0x2a, 0x19, 0x7f, 0x56, 0x03, 0xe3, 0xa2, 0x88, 0x1d, 0x1d, 0x83, 0xe4, 0x00, 0x8f, 0x91, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x311c61f0, 0xab2f32b7, 0xb1f0223f, 0xa72f0a78, 0x752b8146, 0xe46107f8, 0x876dd9c4, 0xf92b2942), 0}, + {{0x94, 0x3c, 0x2f, 0x77, 0x51, 0x08, 0xb7, 0x37, 0xfe, 0x65, 0xa9, 0x53, 0x1e, 0x19, 0xf2, 0xfc, 0x2a, 0x19, 0x7f, 0x56, 0x03, 0xe3, 0xa2, 0x88, 0x1d, 0x1d, 0x83, 0xe4, 0x00, 0x8f, 0x91, 0x25, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x311c61f0, 0xab2f32b7, 0xb1f0223f, 0xa72f0a78, 0x752b8146, 0xe46107f8, 0x876dd9c4, 0xf92b2942), 0}, + {{0xa0, 0xf1, 0x84, 0x92, 0x18, 0x3e, 0x61, 0xe8, 0x06, 0x3e, 0x57, 0x36, 0x06, 0x59, 0x14, 0x21, 0xb0, 0x6b, 0xc3, 0x51, 0x36, 0x31, 0x57, 0x8a, 0x73, 0xa3, 0x9c, 0x1c, 0x33, 0x06, 0x23, 0x9f, 0x2f, 0x32, 0x90, 0x4f, 0x0d, 0x2a, 0x33, 0xec, 0xca, 0x8a, 0x54, 0x51, 0x70, 0x5b, 0xb5, 0x37, 0xd3, 0xbf, 0x44, 0xe0, 0x71, 0x22, 0x60, 0x25, 0xcd, 0xbf, 0xd2, 0x49, 0xfe, 0x0f, 0x7a, 0xd6}, SECP256K1_FE_CONST(0x97a09cf1, 0xa2eae7c4, 0x94df3c6f, 0x8a9445bf, 0xb8c09d60, 0x832f9b0b, 0x9d5eabe2, 0x5fbd14b9), 0}, + {{0xa1, 0xed, 0x0a, 0x0b, 0xd7, 0x9d, 0x8a, 0x23, 0xcf, 0xe4, 0xec, 0x5f, 0xef, 0x5b, 0xa5, 0xcc, 0xcf, 0xd8, 0x44, 0xe4, 0xff, 0x5c, 0xb4, 0xb0, 0xf2, 0xe7, 0x16, 0x27, 0x34, 0x1f, 0x1c, 0x5b, 0x17, 0xc4, 0x99, 0x24, 0x9e, 0x0a, 0xc0, 0x8d, 0x5d, 0x11, 0xea, 0x1c, 0x2c, 0x8c, 0xa7, 0x00, 0x16, 0x16, 0x55, 0x9a, 0x79, 0x94, 0xea, 0xde, 0xc9, 0xca, 0x10, 0xfb, 0x4b, 0x85, 0x16, 0xdc}, SECP256K1_FE_CONST(0x65a89640, 0x744192cd, 0xac64b2d2, 0x1ddf989c, 0xdac75007, 0x25b645be, 0xf8e2200a, 0xe39691f2), 0}, + {{0xba, 0x94, 0x59, 0x4a, 0x43, 0x27, 0x21, 0xaa, 0x35, 0x80, 0xb8, 0x4c, 0x16, 0x1d, 0x0d, 0x13, 0x4b, 0xc3, 0x54, 0xb6, 0x90, 0x40, 0x4d, 0x7c, 0xd4, 0xec, 0x57, 0xc1, 0x6d, 0x3f, 0xbe, 0x98, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xea, 0x50, 0x7d, 0xd7}, SECP256K1_FE_CONST(0x5e0d7656, 0x4aae92cb, 0x347e01a6, 0x2afd389a, 0x9aa401c7, 0x6c8dd227, 0x543dc9cd, 0x0efe685a), 0}, + {{0xbc, 0xaf, 0x72, 0x19, 0xf2, 0xf6, 0xfb, 0xf5, 0x5f, 0xe5, 0xe0, 0x62, 0xdc, 0xe0, 0xe4, 0x8c, 0x18, 0xf6, 0x81, 0x03, 0xf1, 0x0b, 0x81, 0x98, 0xe9, 0x74, 0xc1, 0x84, 0x75, 0x0e, 0x1b, 0xe3, 0x93, 0x20, 0x16, 0xcb, 0xf6, 0x9c, 0x44, 0x71, 0xbd, 0x1f, 0x65, 0x6c, 0x6a, 0x10, 0x7f, 0x19, 0x73, 0xde, 0x4a, 0xf7, 0x08, 0x6d, 0xb8, 0x97, 0x27, 0x70, 0x60, 0xe2, 0x56, 0x77, 0xf1, 0x9a}, SECP256K1_FE_CONST(0x2d97f96c, 0xac882dfe, 0x73dc44db, 0x6ce0f1d3, 0x1d624135, 0x8dd5d74e, 0xb3d3b500, 0x03d24c2b), 0}, + {{0xbc, 0xaf, 0x72, 0x19, 0xf2, 0xf6, 0xfb, 0xf5, 0x5f, 0xe5, 0xe0, 0x62, 0xdc, 0xe0, 0xe4, 0x8c, 0x18, 0xf6, 0x81, 0x03, 0xf1, 0x0b, 0x81, 0x98, 0xe9, 0x74, 0xc1, 0x84, 0x75, 0x0e, 0x1b, 0xe3, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x65, 0x07, 0xd0, 0x9a}, SECP256K1_FE_CONST(0xe7008afe, 0x6e8cbd50, 0x55df120b, 0xd748757c, 0x686dadb4, 0x1cce75e4, 0xaddcc5e0, 0x2ec02b44), 1}, + {{0xc5, 0x98, 0x1b, 0xae, 0x27, 0xfd, 0x84, 0x40, 0x1c, 0x72, 0xa1, 0x55, 0xe5, 0x70, 0x7f, 0xbb, 0x81, 0x1b, 0x2b, 0x62, 0x06, 0x45, 0xd1, 0x02, 0x8e, 0xa2, 0x70, 0xcb, 0xe0, 0xee, 0x22, 0x5d, 0x4b, 0x62, 0xaa, 0x4d, 0xca, 0x65, 0x06, 0xc1, 0xac, 0xdb, 0xec, 0xc0, 0x55, 0x25, 0x69, 0xb4, 0xb2, 0x14, 0x36, 0xa5, 0x69, 0x2e, 0x25, 0xd9, 0x0d, 0x3b, 0xc2, 0xeb, 0x7c, 0xe2, 0x40, 0x78}, SECP256K1_FE_CONST(0x948b40e7, 0x181713bc, 0x018ec170, 0x2d3d054d, 0x15746c59, 0xa7020730, 0xdd13ecf9, 0x85a010d7), 0}, + {{0xc8, 0x94, 0xce, 0x48, 0xbf, 0xec, 0x43, 0x30, 0x14, 0xb9, 0x31, 0xa6, 0xad, 0x42, 0x26, 0xd7, 0xdb, 0xd8, 0xea, 0xa7, 0xb6, 0xe3, 0xfa, 0xa8, 0xd0, 0xef, 0x94, 0x05, 0x2b, 0xcf, 0x8c, 0xff, 0x33, 0x6e, 0xeb, 0x39, 0x19, 0xe2, 0xb4, 0xef, 0xb7, 0x46, 0xc7, 0xf7, 0x1b, 0xbc, 0xa7, 0xe9, 0x38, 0x32, 0x30, 0xfb, 0xbc, 0x48, 0xff, 0xaf, 0xe7, 0x7e, 0x8b, 0xcc, 0x69, 0x54, 0x24, 0x71}, SECP256K1_FE_CONST(0xf1c91acd, 0xc2525330, 0xf9b53158, 0x434a4d43, 0xa1c547cf, 0xf29f1550, 0x6f5da4eb, 0x4fe8fa5a), 1}, + {{0xcb, 0xb0, 0xde, 0xab, 0x12, 0x57, 0x54, 0xf1, 0xfd, 0xb2, 0x03, 0x8b, 0x04, 0x34, 0xed, 0x9c, 0xb3, 0xfb, 0x53, 0xab, 0x73, 0x53, 0x91, 0x12, 0x99, 0x94, 0xa5, 0x35, 0xd9, 0x25, 0xf6, 0x73, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x872d81ed, 0x8831d999, 0x8b67cb71, 0x05243edb, 0xf86c10ed, 0xfebb786c, 0x110b02d0, 0x7b2e67cd), 0}, + {{0xd9, 0x17, 0xb7, 0x86, 0xda, 0xc3, 0x56, 0x70, 0xc3, 0x30, 0xc9, 0xc5, 0xae, 0x59, 0x71, 0xdf, 0xb4, 0x95, 0xc8, 0xae, 0x52, 0x3e, 0xd9, 0x7e, 0xe2, 0x42, 0x01, 0x17, 0xb1, 0x71, 0xf4, 0x1e, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x20, 0x01, 0xf6, 0xf6}, SECP256K1_FE_CONST(0xe45b71e1, 0x10b831f2, 0xbdad8651, 0x994526e5, 0x8393fde4, 0x328b1ec0, 0x4d598971, 0x42584691), 1}, + {{0xe2, 0x8b, 0xd8, 0xf5, 0x92, 0x9b, 0x46, 0x7e, 0xb7, 0x0e, 0x04, 0x33, 0x23, 0x74, 0xff, 0xb7, 0xe7, 0x18, 0x02, 0x18, 0xad, 0x16, 0xea, 0xa4, 0x6b, 0x71, 0x61, 0xaa, 0x67, 0x9e, 0xb4, 0x26, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x66b8c980, 0xa75c72e5, 0x98d383a3, 0x5a62879f, 0x844242ad, 0x1e73ff12, 0xedaa59f4, 0xe58632b5), 0}, + {{0xe2, 0x8b, 0xd8, 0xf5, 0x92, 0x9b, 0x46, 0x7e, 0xb7, 0x0e, 0x04, 0x33, 0x23, 0x74, 0xff, 0xb7, 0xe7, 0x18, 0x02, 0x18, 0xad, 0x16, 0xea, 0xa4, 0x6b, 0x71, 0x61, 0xaa, 0x67, 0x9e, 0xb4, 0x26, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x66b8c980, 0xa75c72e5, 0x98d383a3, 0x5a62879f, 0x844242ad, 0x1e73ff12, 0xedaa59f4, 0xe58632b5), 0}, + {{0xe7, 0xee, 0x58, 0x14, 0xc1, 0x70, 0x6b, 0xf8, 0xa8, 0x93, 0x96, 0xa9, 0xb0, 0x32, 0xbc, 0x01, 0x4c, 0x2c, 0xac, 0x9c, 0x12, 0x11, 0x27, 0xdb, 0xf6, 0xc9, 0x92, 0x78, 0xf8, 0xbb, 0x53, 0xd1, 0xdf, 0xd0, 0x4d, 0xbc, 0xda, 0x8e, 0x35, 0x24, 0x66, 0xb6, 0xfc, 0xd5, 0xf2, 0xde, 0xa3, 0xe1, 0x7d, 0x5e, 0x13, 0x31, 0x15, 0x88, 0x6e, 0xda, 0x20, 0xdb, 0x8a, 0x12, 0xb5, 0x4d, 0xe7, 0x1b}, SECP256K1_FE_CONST(0xe842c6e3, 0x529b2342, 0x70a5e977, 0x44edc34a, 0x04d7ba94, 0xe44b6d25, 0x23c9cf01, 0x95730a50), 1}, + {{0xf2, 0x92, 0xe4, 0x68, 0x25, 0xf9, 0x22, 0x5a, 0xd2, 0x3d, 0xc0, 0x57, 0xc1, 0xd9, 0x1c, 0x4f, 0x57, 0xfc, 0xb1, 0x38, 0x6f, 0x29, 0xef, 0x10, 0x48, 0x1c, 0xb1, 0xd2, 0x25, 0x18, 0x59, 0x3f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x70, 0x11, 0xc9, 0x89}, SECP256K1_FE_CONST(0x3cea2c53, 0xb8b01701, 0x66ac7da6, 0x7194694a, 0xdacc84d5, 0x6389225e, 0x330134da, 0xb85a4d55), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0xedd1fd3e, 0x327ce90c, 0xc7a35426, 0x14289aee, 0x9682003e, 0x9cf7dcc9, 0xcf2ca974, 0x3be5aa0c), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0x01, 0xd3, 0x47, 0x5b, 0xf7, 0x65, 0x5b, 0x0f, 0xb2, 0xd8, 0x52, 0x92, 0x10, 0x35, 0xb2, 0xef, 0x60, 0x7f, 0x49, 0x06, 0x9b, 0x97, 0x45, 0x4e, 0x67, 0x95, 0x25, 0x10, 0x62, 0x74, 0x17, 0x71}, SECP256K1_FE_CONST(0xb5da00b7, 0x3cd65605, 0x20e7c364, 0x086e7cd2, 0x3a34bf60, 0xd0e707be, 0x9fc34d4c, 0xd5fdfa2c), 1}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0x42, 0x18, 0xf2, 0x0a, 0xe6, 0xc6, 0x46, 0xb3, 0x63, 0xdb, 0x68, 0x60, 0x58, 0x22, 0xfb, 0x14, 0x26, 0x4c, 0xa8, 0xd2, 0x58, 0x7f, 0xdd, 0x6f, 0xbc, 0x75, 0x0d, 0x58, 0x7e, 0x76, 0xa7, 0xee}, SECP256K1_FE_CONST(0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaaa, 0xaaaaaaa9, 0xfffffd6b), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0x82, 0x27, 0x7c, 0x4a, 0x71, 0xf9, 0xd2, 0x2e, 0x66, 0xec, 0xe5, 0x23, 0xf8, 0xfa, 0x08, 0x74, 0x1a, 0x7c, 0x09, 0x12, 0xc6, 0x6a, 0x69, 0xce, 0x68, 0x51, 0x4b, 0xfd, 0x35, 0x15, 0xb4, 0x9f}, SECP256K1_FE_CONST(0xf482f2e2, 0x41753ad0, 0xfb89150d, 0x8491dc1e, 0x34ff0b8a, 0xcfbb442c, 0xfe999e2e, 0x5e6fd1d2), 1}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0x84, 0x21, 0xcc, 0x93, 0x0e, 0x77, 0xc9, 0xf5, 0x14, 0xb6, 0x91, 0x5c, 0x3d, 0xbe, 0x2a, 0x94, 0xc6, 0xd8, 0xf6, 0x90, 0xb5, 0xb7, 0x39, 0x86, 0x4b, 0xa6, 0x78, 0x9f, 0xb8, 0xa5, 0x5d, 0xd0}, SECP256K1_FE_CONST(0x9f59c402, 0x75f5085a, 0x006f05da, 0xe77eb98c, 0x6fd0db1a, 0xb4a72ac4, 0x7eae90a4, 0xfc9e57e0), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0xd1, 0x9c, 0x18, 0x2d, 0x27, 0x59, 0xcd, 0x99, 0x82, 0x42, 0x28, 0xd9, 0x47, 0x99, 0xf8, 0xc6, 0x55, 0x7c, 0x38, 0xa1, 0xc0, 0xd6, 0x77, 0x9b, 0x9d, 0x4b, 0x72, 0x9c, 0x6f, 0x1c, 0xcc, 0x42}, SECP256K1_FE_CONST(0x70720db7, 0xe238d041, 0x21f5b1af, 0xd8cc5ad9, 0xd18944c6, 0xbdc94881, 0xf502b7a3, 0xaf3aecff), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0xedd1fd3e, 0x327ce90c, 0xc7a35426, 0x14289aee, 0x9682003e, 0x9cf7dcc9, 0xcf2ca974, 0x3be5aa0c), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x26, 0x64, 0xbb, 0xd5}, SECP256K1_FE_CONST(0x50873db3, 0x1badcc71, 0x890e4f67, 0x753a6575, 0x7f97aaa7, 0xdd5f1e82, 0xb753ace3, 0x2219064b), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x70, 0x28, 0xde, 0x7d}, SECP256K1_FE_CONST(0x1eea9cc5, 0x9cfcf2fa, 0x151ac6c2, 0x74eea411, 0x0feb4f7b, 0x68c59657, 0x32e9992e, 0x976ef68e), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xcb, 0xcf, 0xb7, 0xe7}, SECP256K1_FE_CONST(0x12303941, 0xaedc2088, 0x80735b1f, 0x1795c8e5, 0x5be520ea, 0x93e10335, 0x7b5d2adb, 0x7ed59b8e), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf3, 0x11, 0x3a, 0xd9}, SECP256K1_FE_CONST(0x7eed6b70, 0xe7b0767c, 0x7d7feac0, 0x4e57aa2a, 0x12fef5e0, 0xf48f878f, 0xcbb88b3b, 0x6b5e0783), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x13, 0xce, 0xa4, 0xa7, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x64998443, 0x5b62b4a2, 0x5d40c613, 0x3e8d9ab8, 0xc53d4b05, 0x9ee8a154, 0xa3be0fcf, 0x4e892edb), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x13, 0xce, 0xa4, 0xa7, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x64998443, 0x5b62b4a2, 0x5d40c613, 0x3e8d9ab8, 0xc53d4b05, 0x9ee8a154, 0xa3be0fcf, 0x4e892edb), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x15, 0x02, 0x8c, 0x59, 0x00, 0x63, 0xf6, 0x4d, 0x5a, 0x7f, 0x1c, 0x14, 0x91, 0x5c, 0xd6, 0x1e, 0xac, 0x88, 0x6a, 0xb2, 0x95, 0xbe, 0xbd, 0x91, 0x99, 0x25, 0x04, 0xcf, 0x77, 0xed, 0xb0, 0x28, 0xbd, 0xd6, 0x26, 0x7f}, SECP256K1_FE_CONST(0x3fde5713, 0xf8282eea, 0xd7d39d42, 0x01f44a7c, 0x85a5ac8a, 0x0681f35e, 0x54085c6b, 0x69543374), 1}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x27, 0x15, 0xde, 0x86, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x3524f77f, 0xa3a6eb43, 0x89c3cb5d, 0x27f1f914, 0x62086429, 0xcd6c0cb0, 0xdf43ea8f, 0x1e7b3fb4), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x27, 0x15, 0xde, 0x86, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x3524f77f, 0xa3a6eb43, 0x89c3cb5d, 0x27f1f914, 0x62086429, 0xcd6c0cb0, 0xdf43ea8f, 0x1e7b3fb4), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x2c, 0x2c, 0x57, 0x09, 0xe7, 0x15, 0x6c, 0x41, 0x77, 0x17, 0xf2, 0xfe, 0xab, 0x14, 0x71, 0x41, 0xec, 0x3d, 0xa1, 0x9f, 0xb7, 0x59, 0x57, 0x5c, 0xc6, 0xe3, 0x7b, 0x2e, 0xa5, 0xac, 0x93, 0x09, 0xf2, 0x6f, 0x0f, 0x66}, SECP256K1_FE_CONST(0xd2469ab3, 0xe04acbb2, 0x1c65a180, 0x9f39caaf, 0xe7a77c13, 0xd10f9dd3, 0x8f391c01, 0xdc499c52), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x3a, 0x08, 0xcc, 0x1e, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf7, 0x60, 0xe9, 0xf0}, SECP256K1_FE_CONST(0x38e2a5ce, 0x6a93e795, 0xe16d2c39, 0x8bc99f03, 0x69202ce2, 0x1e8f09d5, 0x6777b40f, 0xc512bccc), 1}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x3e, 0x91, 0x25, 0x7d, 0x93, 0x20, 0x16, 0xcb, 0xf6, 0x9c, 0x44, 0x71, 0xbd, 0x1f, 0x65, 0x6c, 0x6a, 0x10, 0x7f, 0x19, 0x73, 0xde, 0x4a, 0xf7, 0x08, 0x6d, 0xb8, 0x97, 0x27, 0x70, 0x60, 0xe2, 0x56, 0x77, 0xf1, 0x9a}, SECP256K1_FE_CONST(0x864b3dc9, 0x02c37670, 0x9c10a93a, 0xd4bbe29f, 0xce0012f3, 0xdc8672c6, 0x286bba28, 0xd7d6d6fc), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x79, 0x5d, 0x6c, 0x1c, 0x32, 0x2c, 0xad, 0xf5, 0x99, 0xdb, 0xb8, 0x64, 0x81, 0x52, 0x2b, 0x3c, 0xc5, 0x5f, 0x15, 0xa6, 0x79, 0x32, 0xdb, 0x2a, 0xfa, 0x01, 0x11, 0xd9, 0xed, 0x69, 0x81, 0xbc, 0xd1, 0x24, 0xbf, 0x44}, SECP256K1_FE_CONST(0x766dfe4a, 0x700d9bee, 0x288b903a, 0xd58870e3, 0xd4fe2f0e, 0xf780bcac, 0x5c823f32, 0x0d9a9bef), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x8e, 0x42, 0x6f, 0x03, 0x92, 0x38, 0x90, 0x78, 0xc1, 0x2b, 0x1a, 0x89, 0xe9, 0x54, 0x2f, 0x05, 0x93, 0xbc, 0x96, 0xb6, 0xbf, 0xde, 0x82, 0x24, 0xf8, 0x65, 0x4e, 0xf5, 0xd5, 0xcd, 0xa9, 0x35, 0xa3, 0x58, 0x21, 0x94}, SECP256K1_FE_CONST(0xfaec7bc1, 0x987b6323, 0x3fbc5f95, 0x6edbf37d, 0x54404e74, 0x61c58ab8, 0x631bc68e, 0x451a0478), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x91, 0x19, 0x21, 0x39, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x45, 0xf0, 0xf1, 0xeb}, SECP256K1_FE_CONST(0xec29a50b, 0xae138dbf, 0x7d8e2482, 0x5006bb5f, 0xc1a2cc12, 0x43ba335b, 0xc6116fb9, 0xe498ec1f), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x98, 0xeb, 0x9a, 0xb7, 0x6e, 0x84, 0x49, 0x9c, 0x48, 0x3b, 0x3b, 0xf0, 0x62, 0x14, 0xab, 0xfe, 0x06, 0x5d, 0xdd, 0xf4, 0x3b, 0x86, 0x01, 0xde, 0x59, 0x6d, 0x63, 0xb9, 0xe4, 0x5a, 0x16, 0x6a, 0x58, 0x05, 0x41, 0xfe}, SECP256K1_FE_CONST(0x1e0ff2de, 0xe9b09b13, 0x6292a9e9, 0x10f0d6ac, 0x3e552a64, 0x4bba39e6, 0x4e9dd3e3, 0xbbd3d4d4), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x9b, 0x77, 0xb7, 0xf2, 0xc7, 0x4d, 0x99, 0xef, 0xce, 0xaa, 0x55, 0x0f, 0x1a, 0xd1, 0xc0, 0xf4, 0x3f, 0x46, 0xe7, 0xff, 0x1e, 0xe3, 0xbd, 0x01, 0x62, 0xb7, 0xbf, 0x55, 0xf2, 0x96, 0x5d, 0xa9, 0xc3, 0x45, 0x06, 0x46}, SECP256K1_FE_CONST(0x8b7dd5c3, 0xedba9ee9, 0x7b70eff4, 0x38f22dca, 0x9849c825, 0x4a2f3345, 0xa0a572ff, 0xeaae0928), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x9b, 0x77, 0xb7, 0xf2, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x15, 0x6c, 0xa8, 0x96}, SECP256K1_FE_CONST(0x0881950c, 0x8f51d6b9, 0xa6387465, 0xd5f12609, 0xef1bb254, 0x12a08a74, 0xcb2dfb20, 0x0c74bfbf), 1}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xa2, 0xf5, 0xcd, 0x83, 0x88, 0x16, 0xc1, 0x6c, 0x4f, 0xe8, 0xa1, 0x66, 0x1d, 0x60, 0x6f, 0xdb, 0x13, 0xcf, 0x9a, 0xf0, 0x4b, 0x97, 0x9a, 0x2e, 0x15, 0x9a, 0x09, 0x40, 0x9e, 0xbc, 0x86, 0x45, 0xd5, 0x8f, 0xde, 0x02}, SECP256K1_FE_CONST(0x2f083207, 0xb9fd9b55, 0x0063c31c, 0xd62b8746, 0xbd543bdc, 0x5bbf10e3, 0xa35563e9, 0x27f440c8), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xb1, 0x3f, 0x75, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x4f51e0be, 0x078e0cdd, 0xab274215, 0x6adba7e7, 0xa148e731, 0x57072fd6, 0x18cd6094, 0x2b146bd0), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xb1, 0x3f, 0x75, 0xc0, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x4f51e0be, 0x078e0cdd, 0xab274215, 0x6adba7e7, 0xa148e731, 0x57072fd6, 0x18cd6094, 0x2b146bd0), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xe7, 0xbc, 0x1f, 0x8d, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, SECP256K1_FE_CONST(0x16c2ccb5, 0x4352ff4b, 0xd794f6ef, 0xd613c721, 0x97ab7082, 0xda5b563b, 0xdf9cb3ed, 0xaafe74c2), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xe7, 0xbc, 0x1f, 0x8d, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f}, SECP256K1_FE_CONST(0x16c2ccb5, 0x4352ff4b, 0xd794f6ef, 0xd613c721, 0x97ab7082, 0xda5b563b, 0xdf9cb3ed, 0xaafe74c2), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xef, 0x64, 0xd1, 0x62, 0x75, 0x05, 0x46, 0xce, 0x42, 0xb0, 0x43, 0x13, 0x61, 0xe5, 0x2d, 0x4f, 0x52, 0x42, 0xd8, 0xf2, 0x4f, 0x33, 0xe6, 0xb1, 0xf9, 0x9b, 0x59, 0x16, 0x47, 0xcb, 0xc8, 0x08, 0xf4, 0x62, 0xaf, 0x51}, SECP256K1_FE_CONST(0xd41244d1, 0x1ca4f652, 0x40687759, 0xf95ca9ef, 0xbab767ed, 0xedb38fd1, 0x8c36e18c, 0xd3b6f6a9), 1}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf0, 0xe5, 0xbe, 0x52, 0x37, 0x2d, 0xd6, 0xe8, 0x94, 0xb2, 0xa3, 0x26, 0xfc, 0x36, 0x05, 0xa6, 0xe8, 0xf3, 0xc6, 0x9c, 0x71, 0x0b, 0xf2, 0x7d, 0x63, 0x0d, 0xfe, 0x20, 0x04, 0x98, 0x8b, 0x78, 0xeb, 0x6e, 0xab, 0x36}, SECP256K1_FE_CONST(0x64bf84dd, 0x5e03670f, 0xdb24c0f5, 0xd3c2c365, 0x736f51db, 0x6c92d950, 0x10716ad2, 0xd36134c8), 0}, + {{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0xfb, 0xb9, 0x82, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf6, 0xd6, 0xdb, 0x1f}, SECP256K1_FE_CONST(0x1c92ccdf, 0xcf4ac550, 0xc28db57c, 0xff0c8515, 0xcb26936c, 0x786584a7, 0x0114008d, 0x6c33a34b), 0}, +}; + +/** This is a hasher for ellswift_xdh which just returns the shared X coordinate. + * + * This is generally a bad idea as it means changes to the encoding of the + * exchanged public keys do not affect the shared secret. However, it's used here + * in tests to be able to verify the X coordinate through other means. + */ +static int ellswift_xdh_hash_x32(unsigned char *output, const unsigned char *x32, const unsigned char *ours64, const unsigned char *theirs64, void *data) { + (void)ours64; + (void)theirs64; + (void)data; + memcpy(output, x32, 32); + return 1; +} + +void run_ellswift_tests(void) { + int i = 0; + /* Test vectors. */ + for (i = 0; (unsigned)i < sizeof(ellswift_xswiftec_inv_tests) / sizeof(ellswift_xswiftec_inv_tests[0]); ++i) { + const struct ellswift_xswiftec_inv_test* testcase = &ellswift_xswiftec_inv_tests[i]; + int c; + for (c = 0; c < 8; ++c) { + secp256k1_fe t; + int ret = secp256k1_ellswift_xswiftec_inv_var(&t, &testcase->x, &testcase->u, c); + CHECK(ret == ((testcase->enc_bitmap >> c) & 1)); + if (ret) { + secp256k1_fe x2; + CHECK(check_fe_equal(&t, &testcase->encs[c])); + secp256k1_ellswift_xswiftec_var(&x2, &testcase->u, &testcase->encs[c]); + CHECK(check_fe_equal(&testcase->x, &x2)); + } + } + } + for (i = 0; (unsigned)i < sizeof(ellswift_decode_tests) / sizeof(ellswift_decode_tests[0]); ++i) { + const struct ellswift_decode_test* testcase = &ellswift_decode_tests[i]; + secp256k1_pubkey pubkey; + secp256k1_ge ge; + int ret; + ret = secp256k1_ellswift_decode(CTX, &pubkey, testcase->enc); + CHECK(ret); + ret = secp256k1_pubkey_load(CTX, &ge, &pubkey); + CHECK(ret); + CHECK(check_fe_equal(&testcase->x, &ge.x)); + CHECK(secp256k1_fe_is_odd(&ge.y) == testcase->odd_y); + } + /* Verify that secp256k1_ellswift_encode + decode roundtrips. */ + for (i = 0; i < 1000 * COUNT; i++) { + unsigned char rnd32[32]; + unsigned char ell64[64]; + secp256k1_ge g, g2; + secp256k1_pubkey pubkey, pubkey2; + /* Generate random public key and random randomizer. */ + random_group_element_test(&g); + secp256k1_pubkey_save(&pubkey, &g); + secp256k1_testrand256(rnd32); + /* Convert the public key to ElligatorSwift and back. */ + secp256k1_ellswift_encode(CTX, ell64, &pubkey, rnd32); + secp256k1_ellswift_decode(CTX, &pubkey2, ell64); + secp256k1_pubkey_load(CTX, &g2, &pubkey2); + /* Compare with original. */ + ge_equals_ge(&g, &g2); + } + /* Verify the behavior of secp256k1_ellswift_create */ + for (i = 0; i < 400 * COUNT; i++) { + unsigned char rnd32[32], sec32[32]; + secp256k1_scalar sec; + secp256k1_gej res; + secp256k1_ge dec; + secp256k1_pubkey pub; + unsigned char ell64[64]; + int ret; + /* Generate random secret key and random randomizer. */ + secp256k1_testrand256_test(rnd32); + random_scalar_order_test(&sec); + secp256k1_scalar_get_b32(sec32, &sec); + /* Construct ElligatorSwift-encoded public keys for that key. */ + ret = secp256k1_ellswift_create(CTX, ell64, sec32, rnd32); + CHECK(ret); + /* Decode it, and compare with traditionally-computed public key. */ + secp256k1_ellswift_decode(CTX, &pub, ell64); + secp256k1_pubkey_load(CTX, &dec, &pub); + secp256k1_ecmult(&res, NULL, &secp256k1_scalar_zero, &sec); + ge_equals_gej(&dec, &res); + } + /* Verify that secp256k1_ellswift_xdh computes the right shared X coordinate. */ + for (i = 0; i < 800 * COUNT; i++) { + unsigned char ell64[64], sec32[32], share32[32]; + secp256k1_scalar sec; + secp256k1_ge dec, res; + secp256k1_fe share_x; + secp256k1_gej decj, resj; + secp256k1_pubkey pub; + int ret; + /* Generate random secret key. */ + random_scalar_order_test(&sec); + secp256k1_scalar_get_b32(sec32, &sec); + /* Generate random ElligatorSwift encoding for the remote key and decode it. */ + secp256k1_testrand256_test(ell64); + secp256k1_testrand256_test(ell64 + 32); + secp256k1_ellswift_decode(CTX, &pub, ell64); + secp256k1_pubkey_load(CTX, &dec, &pub); + secp256k1_gej_set_ge(&decj, &dec); + /* Compute the X coordinate of seckey*pubkey using ellswift_xdh. Note that we + * pass ell64 as claimed (but incorrect) encoding for sec32 here; this works + * because the "hasher" function we use here ignores the ours64 argument. */ + ret = secp256k1_ellswift_xdh(CTX, share32, ell64, ell64, sec32, &ellswift_xdh_hash_x32, NULL); + CHECK(ret); + secp256k1_fe_set_b32(&share_x, share32); + /* Compute seckey*pubkey directly. */ + secp256k1_ecmult(&resj, &decj, &sec, NULL); + secp256k1_ge_set_gej(&res, &resj); + /* Compare. */ + CHECK(check_fe_equal(&res.x, &share_x)); + } + /* Verify the joint behavior of secp256k1_ellswift_xdh */ + for (i = 0; i < 200 * COUNT; i++) { + unsigned char rnd32a[32], rnd32b[32], sec32a[32], sec32b[32]; + secp256k1_scalar seca, secb; + unsigned char ell64a[64], ell64b[64]; + unsigned char share32a[32], share32b[32]; + int ret; + /* Generate random secret keys and random randomizers. */ + secp256k1_testrand256_test(rnd32a); + secp256k1_testrand256_test(rnd32b); + random_scalar_order_test(&seca); + random_scalar_order_test(&secb); + secp256k1_scalar_get_b32(sec32a, &seca); + secp256k1_scalar_get_b32(sec32b, &secb); + /* Construct ElligatorSwift-encoded public keys for those keys. */ + ret = secp256k1_ellswift_create(CTX, ell64a, sec32a, rnd32a); + CHECK(ret); + ret = secp256k1_ellswift_create(CTX, ell64b, sec32b, rnd32b); + CHECK(ret); + /* Compute the shared secret both ways and compare with each other. */ + ret = secp256k1_ellswift_xdh(CTX, share32a, ell64a, ell64b, sec32b, NULL, NULL); + CHECK(ret); + ret = secp256k1_ellswift_xdh(CTX, share32b, ell64b, ell64a, sec32a, NULL, NULL); + CHECK(ret); + CHECK(secp256k1_memcmp_var(share32a, share32b, 32) == 0); + /* Verify that the shared secret doesn't match if a secret key or remote pubkey changes. */ + secp256k1_testrand_flip(ell64a, 64); + ret = secp256k1_ellswift_xdh(CTX, share32a, ell64a, ell64b, sec32b, NULL, NULL); + CHECK(ret); + CHECK(secp256k1_memcmp_var(share32a, share32b, 32) != 0); + secp256k1_testrand_flip(sec32a, 32); + ret = secp256k1_ellswift_xdh(CTX, share32a, ell64a, ell64b, sec32b, NULL, NULL); + CHECK(!ret || secp256k1_memcmp_var(share32a, share32b, 32) != 0); + } +} + +#endif diff --git a/src/secp256k1.c b/src/secp256k1.c index 7af333ca900fd..82ef2f8551f9b 100644 --- a/src/secp256k1.c +++ b/src/secp256k1.c @@ -811,3 +811,7 @@ int secp256k1_tagged_sha256(const secp256k1_context* ctx, unsigned char *hash32, #ifdef ENABLE_MODULE_SCHNORRSIG # include "modules/schnorrsig/main_impl.h" #endif + +#ifdef ENABLE_MODULE_ELLSWIFT +# include "modules/ellswift/main_impl.h" +#endif diff --git a/src/tests.c b/src/tests.c index 1c0d7973490ea..f407f29f67371 100644 --- a/src/tests.c +++ b/src/tests.c @@ -3692,7 +3692,7 @@ static void test_ge(void) { */ secp256k1_ge *ge = (secp256k1_ge *)checked_malloc(&CTX->error_callback, sizeof(secp256k1_ge) * (1 + 4 * runs)); secp256k1_gej *gej = (secp256k1_gej *)checked_malloc(&CTX->error_callback, sizeof(secp256k1_gej) * (1 + 4 * runs)); - secp256k1_fe zf; + secp256k1_fe zf, r; secp256k1_fe zfi2, zfi3; secp256k1_gej_set_infinity(&gej[0]); @@ -3734,6 +3734,11 @@ static void test_ge(void) { secp256k1_fe_sqr(&zfi2, &zfi3); secp256k1_fe_mul(&zfi3, &zfi3, &zfi2); + /* Generate random r */ + do { + random_field_element_test(&r); + } while(secp256k1_fe_is_zero(&r)); + for (i1 = 0; i1 < 1 + 4 * runs; i1++) { int i2; for (i2 = 0; i2 < 1 + 4 * runs; i2++) { @@ -3846,6 +3851,29 @@ static void test_ge(void) { free(ge_set_all); } + /* Test all elements have X coordinates on the curve. */ + for (i = 1; i < 4 * runs + 1; i++) { + secp256k1_fe n; + CHECK(secp256k1_ge_x_on_curve_var(&ge[i].x)); + /* And the same holds after random rescaling. */ + secp256k1_fe_mul(&n, &zf, &ge[i].x); + CHECK(secp256k1_ge_x_frac_on_curve_var(&n, &zf)); + } + + /* Test correspondence secp256k1_ge_x{,_frac}_on_curve_var with ge_set_xo. */ + { + secp256k1_fe n; + secp256k1_ge q; + int ret_on_curve, ret_frac_on_curve, ret_set_xo; + secp256k1_fe_mul(&n, &zf, &r); + ret_on_curve = secp256k1_ge_x_on_curve_var(&r); + ret_frac_on_curve = secp256k1_ge_x_frac_on_curve_var(&n, &zf); + ret_set_xo = secp256k1_ge_set_xo_var(&q, &r, 0); + CHECK(ret_on_curve == ret_frac_on_curve); + CHECK(ret_on_curve == ret_set_xo); + if (ret_set_xo) CHECK(secp256k1_fe_equal_var(&r, &q.x)); + } + /* Test batch gej -> ge conversion with many infinities. */ for (i = 0; i < 4 * runs + 1; i++) { int odd; @@ -4452,6 +4480,68 @@ static void ecmult_const_mult_zero_one(void) { ge_equals_ge(&res2, &point); } +static void ecmult_const_mult_xonly(void) { + int i; + + /* Test correspondence between secp256k1_ecmult_const and secp256k1_ecmult_const_xonly. */ + for (i = 0; i < 2*COUNT; ++i) { + secp256k1_ge base; + secp256k1_gej basej, resj; + secp256k1_fe n, d, resx, v; + secp256k1_scalar q; + int res; + /* Random base point. */ + random_group_element_test(&base); + /* Random scalar to multiply it with. */ + random_scalar_order_test(&q); + /* If i is odd, n=d*base.x for random non-zero d */ + if (i & 1) { + do { + random_field_element_test(&d); + } while (secp256k1_fe_normalizes_to_zero_var(&d)); + secp256k1_fe_mul(&n, &base.x, &d); + } else { + n = base.x; + } + /* Perform x-only multiplication. */ + res = secp256k1_ecmult_const_xonly(&resx, &n, (i & 1) ? &d : NULL, &q, 256, i & 2); + CHECK(res); + /* Perform normal multiplication. */ + secp256k1_gej_set_ge(&basej, &base); + secp256k1_ecmult(&resj, &basej, &q, NULL); + /* Check that resj's X coordinate corresponds with resx. */ + secp256k1_fe_sqr(&v, &resj.z); + secp256k1_fe_mul(&v, &v, &resx); + CHECK(check_fe_equal(&v, &resj.x)); + } + + /* Test that secp256k1_ecmult_const_xonly correctly rejects X coordinates not on curve. */ + for (i = 0; i < 2*COUNT; ++i) { + secp256k1_fe x, n, d, c, r; + int res; + secp256k1_scalar q; + random_scalar_order_test(&q); + /* Generate random X coordinate not on the curve. */ + do { + random_field_element_test(&x); + secp256k1_fe_sqr(&c, &x); + secp256k1_fe_mul(&c, &c, &x); + secp256k1_fe_add(&c, &secp256k1_fe_const_b); + } while (secp256k1_fe_is_square_var(&c)); + /* If i is odd, n=d*x for random non-zero d. */ + if (i & 1) { + do { + random_field_element_test(&d); + } while (secp256k1_fe_normalizes_to_zero_var(&d)); + secp256k1_fe_mul(&n, &x, &d); + } else { + n = x; + } + res = secp256k1_ecmult_const_xonly(&r, &n, (i & 1) ? &d : NULL, &q, 256, 0); + CHECK(res == 0); + } +} + static void ecmult_const_chain_multiply(void) { /* Check known result (randomly generated test problem from sage) */ const secp256k1_scalar scalar = SECP256K1_SCALAR_CONST( @@ -4483,6 +4573,7 @@ static void run_ecmult_const_tests(void) { ecmult_const_random_mult(); ecmult_const_commutativity(); ecmult_const_chain_multiply(); + ecmult_const_mult_xonly(); } typedef struct { @@ -7322,6 +7413,10 @@ static void run_ecdsa_edge_cases(void) { # include "modules/schnorrsig/tests_impl.h" #endif +#ifdef ENABLE_MODULE_ELLSWIFT +# include "modules/ellswift/tests_impl.h" +#endif + static void run_secp256k1_memczero_test(void) { unsigned char buf1[6] = {1, 2, 3, 4, 5, 6}; unsigned char buf2[sizeof(buf1)]; @@ -7652,6 +7747,10 @@ int main(int argc, char **argv) { run_schnorrsig_tests(); #endif +#ifdef ENABLE_MODULE_ELLSWIFT + run_ellswift_tests(); +#endif + /* util tests */ run_secp256k1_memczero_test(); run_secp256k1_byteorder_tests(); diff --git a/src/tests_exhaustive.c b/src/tests_exhaustive.c index 86b9334caedb2..ea81568726bfd 100644 --- a/src/tests_exhaustive.c +++ b/src/tests_exhaustive.c @@ -59,6 +59,19 @@ static void random_fe(secp256k1_fe *x) { } } while(1); } + +static void random_fe_non_zero(secp256k1_fe *nz) { + int tries = 10; + while (--tries >= 0) { + random_fe(nz); + secp256k1_fe_normalize(nz); + if (!secp256k1_fe_is_zero(nz)) { + break; + } + } + /* Infinitesimal probability of spurious failure here */ + CHECK(tries >= 0); +} /** END stolen from tests.c */ static uint32_t num_cores = 1; @@ -174,13 +187,39 @@ static void test_exhaustive_ecmult(const secp256k1_ge *group, const secp256k1_ge secp256k1_ecmult(&tmp, &groupj[r_log], &na, &ng); ge_equals_gej(&group[(i * r_log + j) % EXHAUSTIVE_TEST_ORDER], &tmp); - if (i > 0) { - secp256k1_ecmult_const(&tmp, &group[i], &ng, 256); - ge_equals_gej(&group[(i * j) % EXHAUSTIVE_TEST_ORDER], &tmp); - } } } } + + for (j = 0; j < EXHAUSTIVE_TEST_ORDER; j++) { + for (i = 1; i < EXHAUSTIVE_TEST_ORDER; i++) { + int ret; + secp256k1_gej tmp; + secp256k1_fe xn, xd, tmpf; + secp256k1_scalar na, ng; + + if (skip_section(&iter)) continue; + + secp256k1_scalar_set_int(&na, i); + secp256k1_scalar_set_int(&ng, j); + + /* Test secp256k1_ecmult_const. */ + secp256k1_ecmult_const(&tmp, &group[i], &ng, 256); + ge_equals_gej(&group[(i * j) % EXHAUSTIVE_TEST_ORDER], &tmp); + + /* Test secp256k1_ecmult_const_xonly with all curve X coordinates, and xd=NULL. */ + ret = secp256k1_ecmult_const_xonly(&tmpf, &group[i].x, NULL, &ng, 256, 0); + CHECK(ret); + CHECK(secp256k1_fe_equal_var(&tmpf, &group[(i * j) % EXHAUSTIVE_TEST_ORDER].x)); + + /* Test secp256k1_ecmult_const_xonly with all curve X coordinates, with random xd. */ + random_fe_non_zero(&xd); + secp256k1_fe_mul(&xn, &xd, &group[i].x); + ret = secp256k1_ecmult_const_xonly(&tmpf, &xn, &xd, &ng, 256, 0); + CHECK(ret); + CHECK(secp256k1_fe_equal_var(&tmpf, &group[(i * j) % EXHAUSTIVE_TEST_ORDER].x)); + } + } } typedef struct { From 13423e6054d2369038a001fb937b30c6a05de970 Mon Sep 17 00:00:00 2001 From: dhruv <856960+dhruv@users.noreply.github.com> Date: Tue, 2 Nov 2021 14:44:06 -0700 Subject: [PATCH 2/4] Encode CKey to ElligatorSwift representation --- build_msvc/libsecp256k1/libsecp256k1.vcxproj | 2 +- configure.ac | 2 +- src/key.cpp | 17 +++++++++ src/key.h | 4 ++ src/pubkey.h | 5 +++ src/test/key_tests.cpp | 39 ++++++++++++++++++++ 6 files changed, 67 insertions(+), 2 deletions(-) diff --git a/build_msvc/libsecp256k1/libsecp256k1.vcxproj b/build_msvc/libsecp256k1/libsecp256k1.vcxproj index 0b90f341a7b49..ffe921170f8be 100644 --- a/build_msvc/libsecp256k1/libsecp256k1.vcxproj +++ b/build_msvc/libsecp256k1/libsecp256k1.vcxproj @@ -14,7 +14,7 @@ - ENABLE_MODULE_RECOVERY;ENABLE_MODULE_EXTRAKEYS;ENABLE_MODULE_SCHNORRSIG;%(PreprocessorDefinitions) + ENABLE_MODULE_RECOVERY;ENABLE_MODULE_EXTRAKEYS;ENABLE_MODULE_SCHNORRSIG;ENABLE_MODULE_ELLSWIFT;%(PreprocessorDefinitions) ..\..\src\secp256k1;%(AdditionalIncludeDirectories) 4146;4244;4267;4334 diff --git a/configure.ac b/configure.ac index cbe3dbcf19794..e5b1e45f1dd8f 100644 --- a/configure.ac +++ b/configure.ac @@ -1989,7 +1989,7 @@ CPPFLAGS_TEMP="$CPPFLAGS" unset CPPFLAGS CPPFLAGS="$CPPFLAGS_TEMP" -ac_configure_args="${ac_configure_args} --disable-shared --with-pic --enable-benchmark=no --enable-module-recovery --disable-module-ecdh" +ac_configure_args="${ac_configure_args} --disable-shared --with-pic --enable-benchmark=no --enable-module-recovery --disable-module-ecdh --enable-experimental --enable-module-ellswift" AC_CONFIG_SUBDIRS([src/secp256k1]) AC_OUTPUT diff --git a/src/key.cpp b/src/key.cpp index 3a3f0b2bc2417..e8600a5a453bc 100644 --- a/src/key.cpp +++ b/src/key.cpp @@ -9,8 +9,10 @@ #include #include #include +#include #include +#include #include #include #include @@ -331,6 +333,21 @@ bool CKey::Derive(CKey& keyChild, ChainCode &ccChild, unsigned int nChild, const return ret; } +EllSwiftPubKey CKey::EllSwiftEncode(const std::array& rnd32) const +{ + assert(fValid); + EllSwiftPubKey encoded_pubkey; + + auto success = secp256k1_ellswift_create(secp256k1_context_sign, + reinterpret_cast(encoded_pubkey.data()), + keydata.data(), + UCharCast(rnd32.data())); + + // Should always succeed for valid keys (asserted above) + assert(success); + return encoded_pubkey; +} + bool CExtKey::Derive(CExtKey &out, unsigned int _nChild) const { if (nDepth == std::numeric_limits::max()) return false; out.nDepth = nDepth + 1; diff --git a/src/key.h b/src/key.h index 4e092fffeadad..006efed47fe53 100644 --- a/src/key.h +++ b/src/key.h @@ -12,6 +12,8 @@ #include #include +#include +#include #include #include @@ -156,6 +158,8 @@ class CKey //! Load private key and check that public key matches. bool Load(const CPrivKey& privkey, const CPubKey& vchPubKey, bool fSkipCheck); + + EllSwiftPubKey EllSwiftEncode(const std::array& rnd32) const; }; struct CExtKey { diff --git a/src/pubkey.h b/src/pubkey.h index b3edafea7f82e..b22dc76e0a66a 100644 --- a/src/pubkey.h +++ b/src/pubkey.h @@ -12,6 +12,8 @@ #include #include +#include +#include #include #include #include @@ -29,6 +31,9 @@ class CKeyID : public uint160 typedef uint256 ChainCode; +constexpr size_t ELLSWIFT_ENCODED_SIZE = 64; +using EllSwiftPubKey = std::array; + /** An encapsulated public key. */ class CPubKey { diff --git a/src/test/key_tests.cpp b/src/test/key_tests.cpp index ea5b94f3a5cee..10918ccd16a4f 100644 --- a/src/test/key_tests.cpp +++ b/src/test/key_tests.cpp @@ -5,6 +5,9 @@ #include #include +#include +#include +#include #include #include #include @@ -13,6 +16,8 @@ #include #include +#include +#include #include #include @@ -344,4 +349,38 @@ BOOST_AUTO_TEST_CASE(bip340_test_vectors) } } +CPubKey EllSwiftDecode(const EllSwiftPubKey& encoded_pubkey) +{ + secp256k1_pubkey pubkey; + secp256k1_ellswift_decode(secp256k1_context_static, &pubkey, reinterpret_cast(encoded_pubkey.data())); + + size_t sz = CPubKey::COMPRESSED_SIZE; + std::array vch_bytes; + + secp256k1_ec_pubkey_serialize(secp256k1_context_static, vch_bytes.data(), &sz, &pubkey, SECP256K1_EC_COMPRESSED); + + return CPubKey{vch_bytes.begin(), vch_bytes.end()}; +} + +BOOST_AUTO_TEST_CASE(key_ellswift) +{ + for (const auto& secret : {strSecret1, strSecret2, strSecret1C, strSecret2C}) { + CKey key = DecodeSecret(secret); + BOOST_CHECK(key.IsValid()); + + std::array rnd32; + GetRandBytes({reinterpret_cast(rnd32.data()), 32}); + auto ellswift_encoded_pubkey = key.EllSwiftEncode(rnd32); + + CPubKey decoded_pubkey = EllSwiftDecode(ellswift_encoded_pubkey); + if (!key.IsCompressed()) { + // The decoding constructor returns a compressed pubkey. If the + // original was uncompressed, we must decompress the decoded one + // to compare. + decoded_pubkey.Decompress(); + } + BOOST_CHECK(key.GetPubKey() == decoded_pubkey); + } +} + BOOST_AUTO_TEST_SUITE_END() From 697a23765e3e3b12bbaeb0bf0ce5fc247d24b5be Mon Sep 17 00:00:00 2001 From: dhruv <856960+dhruv@users.noreply.github.com> Date: Wed, 3 Nov 2021 10:08:51 -0700 Subject: [PATCH 3/4] Bench tests for CKey->EllSwift --- src/Makefile.bench.include | 1 + src/bench/ellswift.cpp | 28 ++++++++++++++++++++++++++++ 2 files changed, 29 insertions(+) create mode 100644 src/bench/ellswift.cpp diff --git a/src/Makefile.bench.include b/src/Makefile.bench.include index f1e4e706a1fe3..0479a09a4a97c 100644 --- a/src/Makefile.bench.include +++ b/src/Makefile.bench.include @@ -29,6 +29,7 @@ bench_bench_bitcoin_SOURCES = \ bench/data.h \ bench/descriptors.cpp \ bench/duplicate_inputs.cpp \ + bench/ellswift.cpp \ bench/examples.cpp \ bench/gcs_filter.cpp \ bench/hashpadding.cpp \ diff --git a/src/bench/ellswift.cpp b/src/bench/ellswift.cpp new file mode 100644 index 0000000000000..3ce5cc3d41955 --- /dev/null +++ b/src/bench/ellswift.cpp @@ -0,0 +1,28 @@ +// Copyright (c) 2016-2020 The Bitcoin Core developers +// Distributed under the MIT software license, see the accompanying +// file COPYING or http://www.opensource.org/licenses/mit-license.php. + +#include + +#include +#include + +#include +#include + +static void EllSwiftEncode(benchmark::Bench& bench) +{ + ECC_Start(); + + CKey key; + key.MakeNewKey(true); + + bench.batch(1).unit("pubkey").run([&] { + std::array rnd32; + GetRandBytes({reinterpret_cast(rnd32.data()), 32}); + key.EllSwiftEncode(rnd32); + }); + ECC_Stop(); +} + +BENCHMARK(EllSwiftEncode, benchmark::PriorityLevel::HIGH); From ae4b695aac28acae4b7236df58386457b18d814d Mon Sep 17 00:00:00 2001 From: dhruv <856960+dhruv@users.noreply.github.com> Date: Wed, 3 Nov 2021 10:10:10 -0700 Subject: [PATCH 4/4] Fuzz tests for CKey->EllSwift --- src/test/fuzz/key.cpp | 41 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) diff --git a/src/test/fuzz/key.cpp b/src/test/fuzz/key.cpp index ea6883c08d56f..deb282b8bfd84 100644 --- a/src/test/fuzz/key.cpp +++ b/src/test/fuzz/key.cpp @@ -15,10 +15,14 @@ #include