Files
serai/crypto/schnorr
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
..
2025-08-29 05:21:43 -04:00
2025-08-25 10:06:35 -04:00

Schnorr Signatures

A challenge (and therefore HRAm) agnostic Schnorr signature library. This is intended to be used as a primitive by a variety of crates relying on Schnorr signatures, voiding the need to constantly define a Schnorr signature struct with associated functions.

This library provides signatures of the R, s form. Batch verification is supported via the multiexp crate. Half-aggregation, as defined in https://eprint.iacr.org/2021/350, is also supported.

This library was audited by Cypher Stack in March 2023, culminating in commit 669d2dbffc1dafb82a09d9419ea182667115df06. Any subsequent changes have not undergone auditing.

This library is usable under no_std, via alloc, when the default features are disabled.