Fix wNAF scalar multiplication for big-endian scalar repr#1689
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tob-scott-a wants to merge 1 commit intoRustCrypto:wnaffrom
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Fix wNAF scalar multiplication for big-endian scalar repr#1689tob-scott-a wants to merge 1 commit intoRustCrypto:wnaffrom
tob-scott-a wants to merge 1 commit intoRustCrypto:wnaffrom
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Two bugs prevented wNAF from working with NIST/SEC1 curves: 1. The group crate's wnaf_form() assumes Scalar::to_repr() returns little-endian bytes, but ff::PrimeField documents repr endianness as implementation-specific. All SEC1 curves use big-endian. Fix: add WnafGroup::scalar_repr_to_le_bytes() with a default LE-passthrough; primeorder overrides it to reverse bytes. 2. wnaf_form() drops the final carry when the scalar fills all bit_len bits. This was masked on BLS12-381 (255-bit modulus in 256 bits) but fails on p256 (256-bit modulus in 256 bits). Fix: emit remaining carry after the loop (in group crate). Also implements recommended_wnaf_for_num_scalars (was todo!()). Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This was referenced Mar 19, 2026
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Note: This depends on RustCrypto/group#10, otherwise the tests fail.