This helps identify where the various functionalities are used, or rather, not
used. The `Ciphersuite` trait present in `patches/ciphersuite`, facilitating
the entire FCMP++ tree, only requires the markers _and_ canonical point
decoding. I've opened a PR to upstream such a trait into `group`
(https://github.com/zkcrypto/group/pull/68).
`WrappedGroup` is still justified for as long as `Group::generator` exists.
Moving `::generator()` to its own trait, on an independent structure (upstream)
would be massively appreciated. @tarcieri also wanted to update from
`fn generator()` to `const GENERATOR`, which would encourage further discussion
on https://github.com/zkcrypto/group/issues/32 and
https://github.com/zkcrypto/group/issues/45, which have been stagnant.
The `Id` trait is occasionally used yet really should be first off the chopping
block.
Finally, `WithPreferredHash` is only actually used around a third of the time,
which more than justifies it being a separate trait.
---
Updates `dalek_ff_group::Scalar` to directly re-export
`curve25519_dalek::Scalar`, as without issue. `dalek_ff_group::RistrettoPoint`
also could be replaced with an export of `curve25519_dalek::RistrettoPoint`,
yet the coordinator relies on how we implemented `Hash` on it for the hell of
it so it isn't worth it at this time. `dalek_ff_group::EdwardsPoint` can't be
replaced for an re-export of `curve25519_dalek::SubgroupPoint` as it doesn't
implement `zeroize`, `subtle` traits within a released, non-yanked version.
Relevance to https://github.com/serai-dex/serai/issues/201 and
https://github.com/dalek-cryptography/curve25519-dalek/issues/811#issuecomment-3247732746.
Also updates the `Ristretto` ciphersuite to prefer `Blake2b-512` over
`SHA2-512`. In order to maintain compliance with FROST's IETF standard,
`modular-frost` defines its own ciphersuite for Ristretto which still uses
`SHA2-512`.
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.
Unused and unpublished. This was only added in the FCMP++ branch as a quick fix
for performance reasons. Finding a better API is still a tricky question, but
this API is _bad_.
* Partial move to ff 0.13
It turns out the newly released k256 0.12 isn't on ff 0.13, preventing further
work at this time.
* Update all crates to work on ff 0.13
The provided curves still need to be expanded to fit the new API.
* Finish adding dalek-ff-group ff 0.13 constants
* Correct FieldElement::product definition
Also stops exporting macros.
* Test most new parts of ff 0.13
* Additionally test ff-group-tests with BLS12-381 and the pasta curves
We only tested curves from RustCrypto. Now we test a curve offered by zk-crypto,
the group behind ff/group, and the pasta curves, which is by Zcash (though
Zcash developers are also behind zk-crypto).
* Finish Ed448
Fully specifies all constants, passes all tests in ff-group-tests, and finishes moving to ff-0.13.
* Add RustCrypto/elliptic-curves to allowed git repos
Needed due to k256/p256 incorrectly defining product.
* Finish writing ff 0.13 tests
* Add additional comments to dalek
* Further comments
* Update ethereum-serai to ff 0.13
There's two ways which this could be tested.
1) Preprocess not taking in an arbitrary RNG item, yet the relevant bytes
This would be an unsafe level of refactoring, in my opinion.
2) Test random_nonce and test the passed in RNG eventually ends up at
random_nonce.
This takes the latter route, both verifying random_nonce meets the vectors
and that the FROST machine calls random_nonce properly.
The audit recommends checking failure cases for from_bytes,
from_bytes_unechecked, and from_repr. This isn't feasible.
from_bytes is allowed to have non-canonical values. [0xff; 32] may accordingly
be a valid point for non-SEC1-encoded curves.
from_bytes_unchecked doesn't have a defined failure mode, and by name,
unchecked, shouldn't necessarily fail. The audit acknowledges the tests should
test for whatever result is 'appropriate', yet any result which isn't a failure
on a valid element is appropriate.
from_repr must be canonical, yet for a binary field of 2^n where n % 8 == 0, a
[0xff; n / 8] repr would be valid.
* Add dkg crate
* Remove F_len and G_len
They're generally no longer used.
* Replace hash_to_vec with a provided method around associated type H: Digest
Part of trying to minimize this trait so it can be moved elsewhere. Vec,
which isn't std, may have been a blocker.
* Encrypt secret shares within the FROST library
Reduces requirements on callers in order to be correct.
* Update usage of Zeroize within FROST
* Inline functions in key_gen
There was no reason to have them separated as they were. sign probably
has the same statement available, yet that isn't the focus right now.
* Add a ciphersuite package which provides hash_to_F
* Set the Ciphersuite version to something valid
* Have ed448 export Scalar/FieldElement/Point at the top level
* Move FROST over to Ciphersuite
* Correct usage of ff in ciphersuite
* Correct documentation handling
* Move Schnorr signatures to their own crate
* Remove unused feature from schnorr
* Fix Schnorr tests
* Split DKG into a separate crate
* Add serialize to Commitments and SecretShare
Helper for buf = vec![]; .write(buf).unwrap(); buf
* Move FROST over to the new dkg crate
* Update Monero lib to latest FROST
* Correct ethereum's usage of features
* Add serialize to GeneratorProof
* Add serialize helper function to FROST
* Rename AddendumSerialize to WriteAddendum
* Update processor
* Slight fix to processor
