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RustCrypto/group#12 included a workaround that allows curves with a big endian `PrimeField::Repr` to be used for wNAF, by defining a separate `PrimeField::to_le_repr` method which is always guaranteed to be little endian. This may not be the permanent solution to this problem which gets upstreamed, but it unblocks work for now. This commit adds the relevant impls of `to_le_repr`, along with initial `WnafGroup` impls to `ProjectivePoint` in `k256` and `primeorder` (currently hardcoded to a fixed constant of `4` for now to unblock additional work). This also adds a `ProjectivePoint::wnaf` static method to obtain a wNAF context for that particular curve group, feature-gated on `alloc`. Finally, it adds a smoke test to `p256` which checks it against our scalar multiplication test vectors, however it does not check any other curves yet and probably should.
This was referenced Apr 8, 2026
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RustCrypto/group#12 included a workaround that allows curves with a big endian
PrimeField::Reprto be used for wNAF, by defining a separatePrimeField::to_le_reprmethod which is always guaranteed to be little endian. This may not be the permanent solution to this problem which gets upstreamed, but it unblocks work for now.This commit adds the relevant impls of
to_le_repr, along with initialWnafGroupimpls toProjectivePointink256andprimeorder(currently hardcoded to a fixed constant of4for now to unblock additional work).This also adds a
ProjectivePoint::wnafstatic method to obtain a wNAF context for that particular curve group, feature-gated onalloc.Finally, it adds a smoke test to
p256which checks it against our scalar multiplication test vectors, however it does not check any other curves yet and probably should.