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.
This commit is contained in:
Luke Parker
2025-08-29 05:04:03 -04:00
parent a4811c9a41
commit 90bc364f9f
37 changed files with 355 additions and 416 deletions

View File

@@ -225,7 +225,11 @@ option-ext = { path = "patches/option-ext" }
directories-next = { path = "patches/directories-next" }
# Patch to include `FromUniformBytes<64>` over Scalar
k256 = { git = "https://github.com/kayabaNerve/elliptic-curves", rev = "fc92333e222b7f0cbe268d2ca92ed572f71f3e1d" }
k256 = { git = "https://github.com/kayabaNerve/elliptic-curves", rev = "4994c9ab163781a88cd4a49beae812a89a44e8c3" }
p256 = { git = "https://github.com/kayabaNerve/elliptic-curves", rev = "4994c9ab163781a88cd4a49beae812a89a44e8c3" }
# https://github.com/RustCrypto/hybrid-array/issues/131
hybrid-array = { git = "https://github.com/kayabaNerve/hybrid-array", rev = "8caa508976c93696a67f40734537c91be7cecd96" }
[workspace.lints.clippy]
unwrap_or_default = "allow"