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Supersedes #640.
This commit is contained in:
Luke Parker
2025-01-18 12:31:11 -05:00
parent 2a19e9da93
commit cb906242e7
17 changed files with 36 additions and 31 deletions
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4
crypto/dleq/src/lib.rs
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@@ -37,11 +37,11 @@ pub(crate) fn challenge<T: Transcript, F: PrimeField>(transcript: &mut T) -> F {
// Get a wide amount of bytes to safely reduce without bias
// In most cases, <=1.5x bytes is enough. 2x is still standard and there's some theoretical
// groups which may technically require more than 1.5x bytes for this to work as intended
let target_bytes = ((usize::try_from(F::NUM_BITS).unwrap() + 7) / 8) * 2;
let target_bytes = usize::try_from(F::NUM_BITS).unwrap().div_ceil(8) * 2;
let mut challenge_bytes = transcript.challenge(b"challenge");
let challenge_bytes_len = challenge_bytes.as_ref().len();
// If the challenge is 32 bytes, and we need 64, we need two challenges
let needed_challenges = (target_bytes + (challenge_bytes_len - 1)) / challenge_bytes_len;
let needed_challenges = target_bytes.div_ceil(challenge_bytes_len);
// The following algorithm should be equivalent to a wide reduction of the challenges,
// interpreted as concatenated, big-endian byte string