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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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69
crypto/dalek-ff-group/src/ciphersuite.rs
View File

@@ -1,49 +1,48 @@
use zeroize::Zeroize;
use sha2::Sha512;
use blake2::Blake2b512;
use ciphersuite::{group::Group, Ciphersuite};
use ::ciphersuite::{group::Group, *};
use crate::Scalar;
macro_rules! dalek_curve {
(
$feature: literal,
$Ciphersuite: ident,
$Point: ident,
$ID: literal
) => {
use crate::$Point;
impl Ciphersuite for $Ciphersuite {
type F = Scalar;
type G = $Point;
type H = Sha512;
const ID: &'static [u8] = $ID;
fn generator() -> Self::G {
$Point::generator()
}
}
};
}
use crate::*;
/// Ciphersuite for Ristretto.
#[derive(Clone, Copy, PartialEq, Eq, Debug, Zeroize)]
pub struct Ristretto;
dalek_curve!("ristretto", Ristretto, RistrettoPoint, b"ristretto");
#[test]
fn test_ristretto() {
ff_group_tests::group::test_prime_group_bits::<_, RistrettoPoint>(&mut rand_core::OsRng);
impl WrappedGroup for Ristretto {
type F = Scalar;
type G = RistrettoPoint;
fn generator() -> Self::G {
<RistrettoPoint as Group>::generator()
}
}
impl Id for Ristretto {
const ID: &[u8] = b"ristretto";
}
impl WithPreferredHash for Ristretto {
type H = Blake2b512;
}
impl GroupCanonicalEncoding for Ristretto {
fn from_canonical_bytes(bytes: &<Self::G as GroupEncoding>::Repr) -> CtOption<Self::G> {
Self::G::from_bytes(bytes)
}
}
/// Ciphersuite for Ed25519, inspired by RFC-8032.
/// Ciphersuite for Ed25519.
#[derive(Clone, Copy, PartialEq, Eq, Debug, Zeroize)]
pub struct Ed25519;
dalek_curve!("ed25519", Ed25519, EdwardsPoint, b"edwards25519");
#[test]
fn test_ed25519() {
ff_group_tests::group::test_prime_group_bits::<_, EdwardsPoint>(&mut rand_core::OsRng);
impl WrappedGroup for Ed25519 {
type F = Scalar;
type G = EdwardsPoint;
fn generator() -> Self::G {
<EdwardsPoint as Group>::generator()
}
}
impl Id for Ed25519 {
const ID: &[u8] = b"ed25519";
}
impl WithPreferredHash for Ed25519 {
type H = Sha512;
}
impl GroupCanonicalEncoding for Ed25519 {}