* Impl DefaultIsZeros for every type that uses jubjub::Fr/Scalar
This requires Copy and Clone along with Default. If we do not want to include those, we can impl Zeroize and Drop directly.
* Hash signature message with HStar before deriving the binding factor
To avoid a collision, we should hash our input message, our 'standard' hash is HStar, which uses a domain separator already, and is the same one that generates the binding factor.
* Add a comment about why we hash the signature message before generating the binding factor
* Add comments on how we Zeroize
* Consume nonces with sign()
We want to make sure that the nonces we use when signing are Drop'd
(and thus Zeroize'd) when they go out of scope, so we must move participant_nonces into sign()
Implements FROST (Flexible Round Optimized Schnorr Threshold Signatures, https://eprint.iacr.org/2020/852) where key generation is performed by a trusted dealer.
Future work will include implementing distributed key generation and re-randomizability.
Co-authored-by: Chelsea Komlo <me@chelseakomlo.com>
Co-authored-by: Isis Lovecruft <isis@patternsinthevoid.net>
Deirdre Connolly
Chelsea H. Komlo
Marek