rangeproof: add a bunch more testing

Add two new fixed rangeproof vectors; check that various extracted
values are correct; add a test for creating and verifying single-value
proofs.

Author: apoelstra

src/modules/rangeproof/tests_impl.h

@@ -541,8 +541,95 @@ static void test_rangeproof(void) {
     }
 }
 
+static void test_single_value_proof(uint64_t val) {
+    unsigned char proof[5000];
+    secp256k1_pedersen_commitment commit;
+    unsigned char blind[32];
+    unsigned char blind_out[32];
+    unsigned char nonce[32];
+    const unsigned char message[1] = " "; /* no message will fit into a single-value proof */
+    unsigned char message_out[sizeof(proof)] = { 0 };
+    size_t plen = sizeof(proof);
+    size_t min_val_out = 0;
+    size_t max_val_out = 0;
+    size_t val_out = 0;
+    size_t m_len_out = 0;
+
+    secp256k1_testrand256(blind);
+    secp256k1_testrand256(nonce);
+    CHECK(secp256k1_pedersen_commit(ctx, &commit, blind, val, secp256k1_generator_h));
+
+    CHECK(secp256k1_rangeproof_sign(
+        ctx,
+        proof, &plen,
+        val, /* min_val */
+        &commit, blind, nonce,
+        -1, /* exp: -1 is magic value to indicate a single-value proof */
+        0, /* min_bits */
+        val, /* val */
+        message, sizeof(message),  /* Will cause this to fail */
+        NULL, 0,
+        secp256k1_generator_h
+    ) == 0);
+
+    plen = sizeof(proof);
+    CHECK(secp256k1_rangeproof_sign(
+        ctx,
+        proof, &plen,
+        val, /* min_val */
+        &commit, blind, nonce,
+        -1, /* exp: -1 is magic value to indicate a single-value proof */
+        0, /* min_bits */
+        val, /* val */
+        NULL, 0,
+        NULL, 0,
+        secp256k1_generator_h
+    ) == 1);
+
+    /* Different proof sizes are unfortunate but is caused by `min_value` of
+     * zero being special-cased and encoded more efficiently. */
+    if (val == 0) {
+        CHECK(plen == 65);
+    } else {
+        CHECK(plen == 73);
+    }
+
+    CHECK(secp256k1_rangeproof_verify(
+        ctx,
+        &min_val_out, &max_val_out,
+        &commit,
+        proof, plen,
+        NULL, 0,
+        secp256k1_generator_h
+    ) == 1);
+    CHECK(min_val_out == val);
+    CHECK(max_val_out == val);
+
+    memset(message_out, 0, sizeof(message_out));
+    m_len_out = sizeof(message_out);
+    CHECK(secp256k1_rangeproof_rewind(
+        ctx,
+        blind_out, &val_out,
+        message_out, &m_len_out,
+        nonce,
+        &min_val_out, &max_val_out,
+        &commit,
+        proof, plen,
+        NULL, 0,
+        secp256k1_generator_h
+    ));
+    CHECK(val_out == val);
+    CHECK(min_val_out == val);
+    CHECK(max_val_out == val);
+    CHECK(m_len_out == 0);
+    CHECK(memcmp(blind, blind_out, 32) == 0);
+    for (m_len_out = 0; m_len_out < sizeof(message_out); m_len_out++) {
+        CHECK(message_out[m_len_out] == 0);
+    }
+}
+
 #define MAX_N_GENS	30
-void test_multiple_generators(void) {
+static void test_multiple_generators(void) {
     const size_t n_inputs = (secp256k1_testrand32() % (MAX_N_GENS / 2)) + 1;
     const size_t n_outputs = (secp256k1_testrand32() % (MAX_N_GENS / 2)) + 1;
     const size_t n_generators = n_inputs + n_outputs;
@@ -604,7 +691,18 @@ void test_multiple_generators(void) {
 }
 
 void test_rangeproof_fixed_vectors(void) {
-    const unsigned char vector_1[] = {
+    size_t i;
+    unsigned char blind[32];
+    uint64_t value;
+    uint64_t min_value;
+    uint64_t max_value;
+    secp256k1_pedersen_commitment pc;
+    unsigned char message[4000] = {0};
+    size_t m_len = sizeof(message);
+
+    /* Vector 1: no message */
+{
+    static const unsigned char vector_1[] = {
         0x62, 0x07, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x56, 0x02, 0x2a, 0x5c, 0x42, 0x0e, 0x1d,
         0x51, 0xe1, 0xb7, 0xf3, 0x69, 0x04, 0xb5, 0xbb, 0x9b, 0x41, 0x66, 0x14, 0xf3, 0x64, 0x42, 0x26,
         0xe3, 0xa7, 0x6a, 0x06, 0xbb, 0xa8, 0x5a, 0x49, 0x6f, 0x19, 0x76, 0xfb, 0xe5, 0x75, 0x77, 0x88,
@@ -647,25 +745,175 @@ void test_rangeproof_fixed_vectors(void) {
         0xa6, 0x45, 0xf6, 0xce, 0xcf, 0x48, 0xf6, 0x1e, 0x3d, 0xd2, 0xcf, 0xcb, 0x3a, 0xcd, 0xbb, 0x92,
         0x29, 0x24, 0x16, 0x7f, 0x8a, 0xa8, 0x5c, 0x0c, 0x45, 0x71, 0x33
     };
-    const unsigned char commit_1[] = {
+    static const unsigned char commit_1[] = {
         0x08,
         0xf5, 0x1e, 0x0d, 0xc5, 0x86, 0x78, 0x51, 0xa9, 0x00, 0x00, 0xef, 0x4d, 0xe2, 0x94, 0x60, 0x89,
         0x83, 0x04, 0xb4, 0x0e, 0x90, 0x10, 0x05, 0x1c, 0x7f, 0xd7, 0x33, 0x92, 0x1f, 0xe7, 0x74, 0x59
     };
-    uint64_t min_value_1;
-    uint64_t max_value_1;
-    secp256k1_pedersen_commitment pc;
+    static const unsigned char blind_1[] = {
+        0x98, 0x44, 0xfc, 0x7a, 0x64, 0xa9, 0xca, 0xdf, 0xf3, 0x2f, 0x9f, 0x02, 0xba, 0x46, 0xc7, 0xd9,
+        0x77, 0x47, 0xa4, 0xd3, 0x53, 0x17, 0xc6, 0x44, 0x30, 0x73, 0x84, 0xeb, 0x1f, 0xbe, 0xa1, 0xfb
+    };
 
     CHECK(secp256k1_pedersen_commitment_parse(ctx, &pc, commit_1));
-
     CHECK(secp256k1_rangeproof_verify(
         ctx,
-        &min_value_1, &max_value_1,
+        &min_value, &max_value,
         &pc,
         vector_1, sizeof(vector_1),
         NULL, 0,
         secp256k1_generator_h
     ));
+    CHECK(min_value == 86);
+    CHECK(max_value == 25586);
+
+    CHECK(secp256k1_rangeproof_rewind(
+        ctx,
+        blind, &value,
+        message, &m_len,
+        pc.data,
+        &min_value, &max_value,
+        &pc,
+        vector_1, sizeof(vector_1),
+        NULL, 0,
+        secp256k1_generator_h
+    ));
+
+    CHECK(memcmp(blind, blind_1, 32) == 0);
+    CHECK(value == 86);
+    CHECK(min_value == 86);
+    CHECK(max_value == 25586);
+    CHECK(m_len == 448); /* length of the sidechannel in the proof */
+    for (i = 0; i < m_len; i++) {
+        /* No message encoded in this vector */
+        CHECK(message[i] == 0);
+    }
+}
+
+    /* Vector 2: embedded message */
+{
+    static const unsigned char vector_2[] = {
+        0x40, 0x03, 0x00, 0x90, 0x1a, 0x61, 0x64, 0xbb, 0x85, 0x1a, 0x78, 0x35, 0x1e, 0xe0, 0xd5, 0x96,
+        0x71, 0x0f, 0x18, 0x8e, 0xf3, 0x33, 0xf0, 0x75, 0xfe, 0xd6, 0xc6, 0x11, 0x6b, 0x42, 0x89, 0xea,
+        0xa2, 0x0c, 0x89, 0x25, 0x37, 0x81, 0x10, 0xf9, 0xf0, 0x9b, 0xda, 0x68, 0x2a, 0xd9, 0x2e, 0x0c,
+        0x45, 0x17, 0x54, 0x6d, 0x02, 0xd2, 0x21, 0x5d, 0xbc, 0x10, 0xf8, 0x8f, 0xf1, 0x92, 0x40, 0xa9,
+        0xc7, 0x24, 0x00, 0x1b, 0xc8, 0x75, 0x0f, 0xf6, 0x8f, 0x93, 0x8b, 0x78, 0x62, 0x73, 0x3c, 0x86,
+        0x4b, 0x61, 0x7c, 0x0f, 0xc6, 0x41, 0xc9, 0xb3, 0xc1, 0x30, 0x7f, 0xd4, 0xee, 0x9f, 0x37, 0x08,
+        0x9b, 0x64, 0x23, 0xd5, 0xe6, 0x1a, 0x03, 0x54, 0x74, 0x9b, 0x0b, 0xae, 0x6f, 0x2b, 0x1e, 0xf5,
+        0x40, 0x44, 0xaa, 0x12, 0xe8, 0xbd, 0xe0, 0xa6, 0x85, 0x89, 0xf1, 0xa9, 0xd0, 0x3f, 0x2e, 0xc6,
+        0x1f, 0x11, 0xf5, 0x44, 0x69, 0x99, 0x31, 0x10, 0x2e, 0x64, 0xc6, 0x44, 0xdb, 0x47, 0x06, 0x6d,
+        0xd5, 0xf2, 0x8d, 0x19, 0x00, 0x39, 0xb8, 0xca, 0xda, 0x5c, 0x1d, 0x83, 0xbd, 0xa3, 0x6d, 0xbf,
+        0x97, 0xdd, 0x83, 0x86, 0xc9, 0x56, 0xe2, 0xbb, 0x37, 0x4b, 0x2d, 0xb5, 0x9d, 0xf2, 0x7a, 0x6a,
+        0x25, 0x47, 0xfa, 0x03, 0x05, 0xc5, 0xda, 0x73, 0xe1, 0x96, 0x15, 0x21, 0x23, 0xe5, 0xef, 0x55,
+        0x36, 0xdd, 0xf1, 0xb1, 0x3f, 0x33, 0x1a, 0x91, 0x6c, 0x73, 0x64, 0xd3, 0x88, 0xe7, 0xc6, 0xc9,
+        0x04, 0x29, 0xae, 0x55, 0x27, 0xa0, 0x80, 0x60, 0xaf, 0x0c, 0x09, 0x2f, 0xc8, 0x1b, 0xe6, 0x16,
+        0x9e, 0xed, 0x29, 0xc7, 0x93, 0xce, 0xc7, 0x0d, 0xdf, 0x1f, 0x28, 0xba, 0xf3, 0x38, 0xc3, 0xaa,
+        0x99, 0xd9, 0x21, 0x41, 0xb8, 0x10, 0xa5, 0x48, 0x37, 0xec, 0x60, 0xda, 0x64, 0x5a, 0x73, 0x55,
+        0xd7, 0xff, 0x23, 0xfa, 0xf6, 0xc6, 0xf4, 0xe2, 0xca, 0x99, 0x2f, 0x30, 0x36, 0x48, 0x73, 0x8b,
+        0x57, 0xa6, 0x62, 0x12, 0xa3, 0xe7, 0x5c, 0xa8, 0xd1, 0xe6, 0x85, 0x05, 0x59, 0xfe, 0x2b, 0x44,
+        0xe4, 0x73, 0x1c, 0xc3, 0x56, 0x32, 0x07, 0x65, 0x4a, 0x58, 0xaf, 0x2b, 0x3f, 0x36, 0xca, 0xb4,
+        0x1d, 0x5c, 0x2a, 0x46, 0x1f, 0xf7, 0x63, 0x59, 0x4f, 0x2b, 0xd0, 0xf6, 0xfc, 0xcf, 0x04, 0x09,
+        0xb7, 0x65, 0x1b
+    };
+    static const unsigned char commit_2[] = {
+        0x09,
+        0x25, 0xa4, 0xbd, 0xc4, 0x57, 0x69, 0xeb, 0x4f, 0x34, 0x0f, 0xea, 0xb8, 0xe4, 0x72, 0x04, 0x54,
+        0x06, 0xe5, 0xd6, 0x85, 0x15, 0x42, 0xea, 0x6e, 0x1d, 0x11, 0x11, 0x9c, 0x56, 0xf8, 0x10, 0x45
+    };
+    static const unsigned char blind_2[] = {
+        0xdc, 0x79, 0x07, 0x89, 0x2d, 0xc4, 0xe3, 0x76, 0xf9, 0x13, 0x38, 0xd6, 0x4b, 0x46, 0xed, 0x9d,
+        0x9b, 0xf6, 0x70, 0x3d, 0x04, 0xcf, 0x96, 0x8c, 0xfd, 0xb5, 0xff, 0x0a, 0x06, 0xc7, 0x08, 0x8b
+    };
+    static const unsigned char message_2[] = "When I see my own likeness in the depths of someone else's consciousness,  I always experience a moment of panic.";
+
+    CHECK(secp256k1_pedersen_commitment_parse(ctx, &pc, commit_2));
+    CHECK(secp256k1_rangeproof_verify(
+        ctx,
+        &min_value, &max_value,
+        &pc,
+        vector_2, sizeof(vector_2),
+        NULL, 0,
+        secp256k1_generator_h
+    ));
+    CHECK(min_value == 0);
+    CHECK(max_value == 15);
+
+    CHECK(secp256k1_rangeproof_rewind(
+        ctx,
+        blind, &value,
+        message, &m_len,
+        pc.data,
+        &min_value, &max_value,
+        &pc,
+        vector_2, sizeof(vector_2),
+        NULL, 0,
+        secp256k1_generator_h
+    ));
+
+    CHECK(memcmp(blind, blind_2, 32) == 0);
+    CHECK(value == 11);
+    CHECK(min_value == 0);
+    CHECK(max_value == 15);
+    CHECK(m_len == 192); /* length of the sidechannel in the proof */
+    CHECK(memcmp(message, message_2, sizeof(message_2)) == 0);
+    for (i = sizeof(message_2); i < m_len; i++) {
+        /* No message encoded in this vector */
+        CHECK(message[i] == 0);
+    }
+}
+
+    /* Vector 3: single-value proof of UINT64_MAX */
+{
+    static const unsigned char vector_3[] = {
+        0x20, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xdc, 0x7d, 0x0b, 0x79, 0x0e, 0xaf, 0x41,
+        0xa5, 0x8e, 0x9b, 0x0c, 0x5b, 0xa3, 0xee, 0x7d, 0xfd, 0x3d, 0x6b, 0xf3, 0xac, 0x04, 0x8a, 0x43,
+        0x75, 0xb0, 0xb7, 0x0e, 0x92, 0xd7, 0xdf, 0xf0, 0x76, 0xc4, 0xa5, 0xb6, 0x2f, 0xf1, 0xb5, 0xfb,
+        0xb4, 0xb6, 0x29, 0xea, 0x34, 0x9b, 0x16, 0x30, 0x0d, 0x06, 0xf1, 0xb4, 0x3f, 0x0d, 0x73, 0x59,
+        0x75, 0xbf, 0x5d, 0x19, 0x59, 0xef, 0x11, 0xf0, 0xbf
+    };
+    static const unsigned char commit_3[] = {
+        0x08,
+        0xc7, 0xea, 0x40, 0x7d, 0x26, 0x38, 0xa2, 0x99, 0xb9, 0x40, 0x22, 0x78, 0x17, 0x57, 0x65, 0xb3,
+        0x36, 0x82, 0x18, 0x42, 0xc5, 0x57, 0x04, 0x5e, 0x58, 0x5e, 0xf6, 0x40, 0x8b, 0x24, 0x73, 0x10
+    };
+    static const unsigned char nonce_3[] = {
+        0x84, 0x50, 0x94, 0x69, 0xa3, 0x4b, 0x6c, 0x62, 0x1a, 0xc7, 0xe2, 0x0e, 0x07, 0x9a, 0x6f, 0x85,
+        0x5f, 0x26, 0x50, 0xcd, 0x88, 0x5a, 0x9f, 0xaa, 0x23, 0x5e, 0x0a, 0xe0, 0x7e, 0xc5, 0xe9, 0xf1
+    };
+    static const unsigned char blind_3[] = {
+        0x68, 0x89, 0x47, 0x8c, 0x77, 0xec, 0xcc, 0x2b, 0x65, 0x01, 0x78, 0x6b, 0x06, 0x8b, 0x38, 0x94,
+        0xc0, 0x6b, 0x9b, 0x4c, 0x02, 0xa6, 0xc8, 0xf6, 0xc0, 0x34, 0xea, 0x35, 0x57, 0xf4, 0xe1, 0x37
+    };
+
+    CHECK(secp256k1_pedersen_commitment_parse(ctx, &pc, commit_3));
+    CHECK(secp256k1_rangeproof_verify(
+        ctx,
+        &min_value, &max_value,
+        &pc,
+        vector_3, sizeof(vector_3),
+        NULL, 0,
+        secp256k1_generator_h
+    ));
+    CHECK(min_value == UINT64_MAX);
+    CHECK(max_value == UINT64_MAX);
+
+    CHECK(secp256k1_rangeproof_rewind(
+        ctx,
+        blind, &value,
+        message, &m_len,
+        nonce_3,
+        &min_value, &max_value,
+        &pc,
+        vector_3, sizeof(vector_3),
+        NULL, 0,
+        secp256k1_generator_h
+    ));
+    CHECK(memcmp(blind, blind_3, 32) == 0);
+    CHECK(value == UINT64_MAX);
+    CHECK(min_value == UINT64_MAX);
+    CHECK(max_value == UINT64_MAX);
+    CHECK(m_len == 0);
+}
 }
 
 void test_pedersen_commitment_fixed_vector(void) {
@@ -690,6 +938,11 @@ void test_pedersen_commitment_fixed_vector(void) {
 void run_rangeproof_tests(void) {
     int i;
     test_api();
+
+    test_single_value_proof(0);
+    test_single_value_proof(12345678);
+    test_single_value_proof(UINT64_MAX);
+
     test_rangeproof_fixed_vectors();
     test_pedersen_commitment_fixed_vector();
     for (i = 0; i < count / 2 + 1; i++) {