Smash the singular Ciphersuite trait into multiple

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`.

crypto/dkg/evrf/src/tests/mod.rs

@@ -4,11 +4,11 @@ use zeroize::Zeroizing;
 use rand_core::OsRng;
 use rand::seq::SliceRandom;
 
-use ciphersuite::{group::ff::Field, Ciphersuite};
+use ciphersuite::{group::ff::Field, WrappedGroup};
 use embedwards25519::Embedwards25519;
 
 use dkg_recovery::recover_key;
-use crate::{Participant, Curves, Generators, VerifyResult, Dkg, Ristretto};
+use crate::{Participant, Curves, Generators, VerifyResult, Dkg, Ed25519};
 
 mod proof;
 
@@ -17,14 +17,14 @@ const PARTICIPANTS: u16 = 5;
 
 #[test]
 fn dkg() {
-  let generators = Generators::<Ristretto>::new(THRESHOLD, PARTICIPANTS);
+  let generators = Generators::<Ed25519>::new(THRESHOLD, PARTICIPANTS);
   let context = [0; 32];
 
   let mut priv_keys = vec![];
   let mut pub_keys = vec![];
   for i in 0 .. PARTICIPANTS {
-    let priv_key = <Embedwards25519 as Ciphersuite>::F::random(&mut OsRng);
-    pub_keys.push(<Embedwards25519 as Ciphersuite>::generator() * priv_key);
+    let priv_key = <Embedwards25519 as WrappedGroup>::F::random(&mut OsRng);
+    pub_keys.push(<Embedwards25519 as WrappedGroup>::generator() * priv_key);
     priv_keys.push((Participant::new(1 + i).unwrap(), Zeroizing::new(priv_key)));
   }
 
@@ -34,27 +34,15 @@ fn dkg() {
   for (i, priv_key) in priv_keys.iter().take(usize::from(THRESHOLD)) {
     participations.insert(
       *i,
-      Dkg::<Ristretto>::participate(
-        &mut OsRng,
-        &generators,
-        context,
-        THRESHOLD,
-        &pub_keys,
-        priv_key,
-      )
-      .unwrap(),
+      Dkg::<Ed25519>::participate(&mut OsRng, &generators, context, THRESHOLD, &pub_keys, priv_key)
+        .unwrap(),
     );
   }
 
-  let VerifyResult::Valid(dkg) = Dkg::<Ristretto>::verify(
-    &mut OsRng,
-    &generators,
-    context,
-    THRESHOLD,
-    &pub_keys,
-    &participations,
-  )
-  .unwrap() else {
+  let VerifyResult::Valid(dkg) =
+    Dkg::<Ed25519>::verify(&mut OsRng, &generators, context, THRESHOLD, &pub_keys, &participations)
+      .unwrap()
+  else {
     panic!("verify didn't return VerifyResult::Valid")
   };
 
@@ -80,7 +68,7 @@ fn dkg() {
 
   // TODO: Test for all possible combinations of keys
   assert_eq!(
-    <<Ristretto as Curves>::ToweringCurve as Ciphersuite>::generator() *
+    <<Ed25519 as Curves>::ToweringCurve as WrappedGroup>::generator() *
       *recover_key(&all_keys.values().cloned().collect::<Vec<_>>()).unwrap(),
     group_key.unwrap()
   );

crypto/dkg/evrf/src/tests/proof.rs

@@ -6,13 +6,13 @@ use zeroize::Zeroizing;
 
 use ciphersuite::{
   group::{ff::Field, Group},
-  Ciphersuite,
+  WrappedGroup,
 };
 
 use generalized_bulletproofs::{Generators, tests::insecure_test_generators};
 
 use crate::{
-  Curves, Ristretto,
+  Curves, Ed25519,
   proof::*,
   tests::{THRESHOLD, PARTICIPANTS},
 };
@@ -20,9 +20,9 @@ use crate::{
 fn proof<C: Curves>() {
   let generators = insecure_test_generators(&mut OsRng, 2048).unwrap();
   let embedded_private_key =
-    Zeroizing::new(<C::EmbeddedCurve as Ciphersuite>::F::random(&mut OsRng));
+    Zeroizing::new(<C::EmbeddedCurve as WrappedGroup>::F::random(&mut OsRng));
   let ecdh_public_keys: [_; PARTICIPANTS as usize] =
-    core::array::from_fn(|_| <C::EmbeddedCurve as Ciphersuite>::G::random(&mut OsRng));
+    core::array::from_fn(|_| <C::EmbeddedCurve as WrappedGroup>::G::random(&mut OsRng));
   let time = Instant::now();
   let res = Proof::<C>::prove(
     &mut OsRng,
@@ -54,5 +54,5 @@ fn proof<C: Curves>() {
 
 #[test]
 fn ristretto_proof() {
-  proof::<Ristretto>();
+  proof::<Ed25519>();
 }