Files
serai/crypto/ciphersuite/README.md
Luke Parker 90bc364f9f Replace Ciphersuite::hash_to_F
The prior-present `Ciphersuite::hash_to_F` was a sin. Implementations took a
DST, yet were not require to securely handle it. It was also biased towards the
requirements of `modular-frost` as `ciphersuite` was originally written all
those years ago, when `modular-frost` had needs exceeding what `ff`, `group`
satisfied.

Now, the hash is bound to produce an output which can be converted to a scalar
with `ff::FromUniformBytes`. A new `hash_to_F`, which accepts a single argument
of the value to hash (removing the potential to insecurely handle the DST by
removing the DST entirely). Due to `digest` yielding a `GenericArray`, yet
`FromUniformBytes` taking a `const usize`, the `ciphersuite` crate now defines
a `FromUniformBytes` trait taking an array (then implemented for all satisfiers
of `ff::FromUniformBytes`). In order to get the array type from the
`GenericArray`, the output of the hash, `digest` is updated to the `0.11`
release candidate which moves to `flexible-array` which solves that problem.

The existing, specific `hash_to_F` functions have been moved to `modular-frost`
as necessary.

`flexible-array` itself is patched to a fork due to
https://github.com/RustCrypto/hybrid-array/issues/131.
2025-08-29 05:21:43 -04:00

37 lines
1.5 KiB
Markdown

# Ciphersuite
Ciphersuites for elliptic curves premised on ff/group.
This library, except for the not recommended Ed448 ciphersuite, was
[audited by Cypher Stack in March 2023](https://github.com/serai-dex/serai/raw/e1bb2c191b7123fd260d008e31656d090d559d21/audits/Cypher%20Stack%20crypto%20March%202023/Audit.pdf),
culminating in commit
[669d2dbffc1dafb82a09d9419ea182667115df06](https://github.com/serai-dex/serai/tree/669d2dbffc1dafb82a09d9419ea182667115df06).
Any subsequent changes have not undergone auditing.
This library is usable under no_std. The `alloc` and `std` features enable
reading from the `io::Read` trait, shimmed by `std-shims` under `alloc`.
### Secp256k1/P-256
Secp256k1 and P-256 are offered via [k256](https://crates.io/crates/k256) and
[p256](https://crates.io/crates/p256), two libraries maintained by
[RustCrypto](https://github.com/RustCrypto).
Please see the [`ciphersuite-kp256`](https://docs.rs/ciphersuite-kp256) crate for more info.
### Ed25519/Ristretto
Ed25519/Ristretto are offered via
[dalek-ff-group](https://crates.io/crates/dalek-ff-group), an ff/group wrapper
around [curve25519-dalek](https://crates.io/crates/curve25519-dalek).
Please see the [`dalek-ff-group`](https://docs.rs/dalek-ff-group) crate for more info.
### Ed448
Ed448 is offered via [minimal-ed448](https://crates.io/crates/minimal-ed448), an
explicitly not recommended, unaudited, incomplete Ed448 implementation, limited
to its prime-order subgroup.
Please see the [`minimal-ed448`](https://docs.rs/minimal-ed448) crate for more info.