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a141deaf36
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`.
embedwards25519
A curve defined over the Ed25519 scalar field.
This curve was found via tevador's script for finding curves (specifically, curve cycles), modified to search for curves whose field is the Ed25519 scalar field (not the Ed25519 field).
p = 0x1000000000000000000000000000000014def9dea2f79cd65812631a5cf5d3ed
q = 0x0fffffffffffffffffffffffffffffffe53f4debb78ff96877063f0306eef96b
D = -420435
y^2 = x^3 - 3*x + 4188043517836764736459661287169077812555441231147410753119540549773825148767
The embedding degree is (q-1)/2.
This curve should not be used with single-coordinate ladders, and points should always be represented in a compressed form (preventing receiving off-curve points).