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Smash the singular Ciphersuite trait into multiple

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This helps identify where the various functionalities are used, or rather, not
used. The `Ciphersuite` trait present in `patches/ciphersuite`, facilitating
the entire FCMP++ tree, only requires the markers _and_ canonical point
decoding. I've opened a PR to upstream such a trait into `group`
(https://github.com/zkcrypto/group/pull/68).

`WrappedGroup` is still justified for as long as `Group::generator` exists.
Moving `::generator()` to its own trait, on an independent structure (upstream)
would be massively appreciated. @tarcieri also wanted to update from
`fn generator()` to `const GENERATOR`, which would encourage further discussion
on https://github.com/zkcrypto/group/issues/32 and
https://github.com/zkcrypto/group/issues/45, which have been stagnant.

The `Id` trait is occasionally used yet really should be first off the chopping
block.

Finally, `WithPreferredHash` is only actually used around a third of the time,
which more than justifies it being a separate trait.

---

Updates `dalek_ff_group::Scalar` to directly re-export
`curve25519_dalek::Scalar`, as without issue. `dalek_ff_group::RistrettoPoint`
also could be replaced with an export of `curve25519_dalek::RistrettoPoint`,
yet the coordinator relies on how we implemented `Hash` on it for the hell of
it so it isn't worth it at this time. `dalek_ff_group::EdwardsPoint` can't be
replaced for an re-export of `curve25519_dalek::SubgroupPoint` as it doesn't
implement `zeroize`, `subtle` traits within a released, non-yanked version.
Relevance to https://github.com/serai-dex/serai/issues/201 and
https://github.com/dalek-cryptography/curve25519-dalek/issues/811#issuecomment-3247732746.

Also updates the `Ristretto` ciphersuite to prefer `Blake2b-512` over
`SHA2-512`. In order to maintain compliance with FROST's IETF standard,
`modular-frost` defines its own ciphersuite for Ristretto which still uses
`SHA2-512`.
This commit is contained in:
Luke Parker
2025-09-03 12:25:37 -04:00
parent 215e41fdb6
commit a141deaf36
124 changed files with 1003 additions and 1211 deletions
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12
crypto/frost/src/curve/kp256.rs
View File

@@ -7,7 +7,7 @@ use ciphersuite::{
ff::{Field, PrimeField},
GroupEncoding,
},
Ciphersuite,
WrappedGroup,
};
use elliptic_curve::{
@@ -20,7 +20,7 @@ use elliptic_curve::{
use crate::{curve::Curve, algorithm::Hram};
#[allow(non_snake_case)]
fn hash_to_F<C: Ciphersuite<F: PrimeField<Repr = GenericArray<u8, U32>>>>(
fn hash_to_F<C: WrappedGroup<F: PrimeField<Repr = GenericArray<u8, U32>>>>(
dst: &[u8],
msg: &[u8],
) -> C::F {
@@ -112,10 +112,10 @@ macro_rules! kp_curve {
impl Hram<$Curve> for $Hram {
#[allow(non_snake_case)]
fn hram(
R: &<$Curve as Ciphersuite>::G,
A: &<$Curve as Ciphersuite>::G,
R: &<$Curve as WrappedGroup>::G,
A: &<$Curve as WrappedGroup>::G,
m: &[u8],
) -> <$Curve as Ciphersuite>::F {
) -> <$Curve as WrappedGroup>::F {
<$Curve as Curve>::hash_to_F(
b"chal",
&[R.to_bytes().as_ref(), A.to_bytes().as_ref(), m].concat(),
@@ -132,7 +132,7 @@ kp_curve!("p256", P256, IetfP256Hram, b"FROST-P256-SHA256-v1");
kp_curve!("secp256k1", Secp256k1, IetfSecp256k1Hram, b"FROST-secp256k1-SHA256-v1");
#[cfg(test)]
fn test_oversize_dst<C: Ciphersuite<F: PrimeField<Repr = GenericArray<u8, U32>>>>() {
fn test_oversize_dst<C: WrappedGroup<F: PrimeField<Repr = GenericArray<u8, U32>>>>() {
use sha2::Digest;
// The draft specifies DSTs >255 bytes should be hashed into a 32-byte DST