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

@@ -27,7 +27,7 @@ short-weierstrass = { path = "../short-weierstrass", default-features = false }
curve25519-dalek = { version = "4", default-features = false, features = ["legacy_compatibility"] }
dalek-ff-group = { path = "../dalek-ff-group", version = "0.4", default-features = false }
blake2 = { version = "0.10", default-features = false }
blake2 = { version = "0.11.0-rc.0", default-features = false }
ciphersuite = { path = "../ciphersuite", version = "0.4", default-features = false }
generalized-bulletproofs-ec-gadgets = { git = "https://github.com/monero-oxide/monero-oxide", rev = "a6f8797007e768488568b821435cf5006517a962", default-features = false, optional = true }
@@ -41,5 +41,5 @@ ff-group-tests = { path = "../ff-group-tests" }
[features]
alloc = ["std-shims", "zeroize/alloc", "prime-field/alloc", "short-weierstrass/alloc", "curve25519-dalek/alloc", "ciphersuite/alloc", "generalized-bulletproofs-ec-gadgets"]
std = ["alloc", "std-shims/std", "zeroize/std", "prime-field/std", "short-weierstrass/std", "blake2/std", "ciphersuite/std", "generalized-bulletproofs-ec-gadgets/std"]
std = ["alloc", "std-shims/std", "zeroize/std", "prime-field/std", "short-weierstrass/std", "ciphersuite/std", "generalized-bulletproofs-ec-gadgets/std"]
default = ["std"]