Smash dkg into dkg, dkg-[recovery, promote, musig, pedpop]

promote and pedpop require dleq, which don't support no-std. All three should
be moved outside the Serai repository, per #597, as none are planned for use
and worth covering under our BBP.

crypto/dkg/promote/src/tests.rs

@@ -0,0 +1,113 @@
+use core::marker::PhantomData;
+use std::collections::HashMap;
+
+use zeroize::{Zeroize, Zeroizing};
+use rand_core::OsRng;
+
+use ciphersuite::{
+  group::{ff::Field, Group},
+  Ciphersuite, Ristretto,
+};
+
+use dkg::*;
+use dkg_recovery::recover_key;
+use crate::{GeneratorPromotion, GeneratorProof};
+
+#[derive(Clone, Copy, PartialEq, Eq, Debug, Zeroize)]
+struct AltGenerator<C: Ciphersuite> {
+  _curve: PhantomData<C>,
+}
+
+impl<C: Ciphersuite> Ciphersuite for AltGenerator<C> {
+  type F = C::F;
+  type G = C::G;
+  type H = C::H;
+
+  const ID: &'static [u8] = b"Alternate Ciphersuite";
+
+  fn generator() -> Self::G {
+    C::G::generator() * <C as Ciphersuite>::hash_to_F(b"DKG Promotion Test", b"generator")
+  }
+
+  fn reduce_512(scalar: [u8; 64]) -> Self::F {
+    <C as Ciphersuite>::reduce_512(scalar)
+  }
+
+  fn hash_to_F(dst: &[u8], data: &[u8]) -> Self::F {
+    <C as Ciphersuite>::hash_to_F(dst, data)
+  }
+}
+
+/// Clone a map without a specific value.
+pub fn clone_without<K: Clone + core::cmp::Eq + core::hash::Hash, V: Clone>(
+  map: &HashMap<K, V>,
+  without: &K,
+) -> HashMap<K, V> {
+  let mut res = map.clone();
+  res.remove(without).unwrap();
+  res
+}
+
+// Test promotion of threshold keys to another generator
+#[test]
+fn test_generator_promotion() {
+  // Generate a set of `ThresholdKeys`
+  const PARTICIPANTS: u16 = 5;
+  let keys: [ThresholdKeys<_>; PARTICIPANTS as usize] = {
+    let shares: [<Ristretto as Ciphersuite>::F; PARTICIPANTS as usize] =
+      core::array::from_fn(|_| <Ristretto as Ciphersuite>::F::random(&mut OsRng));
+    let verification_shares = (0 .. PARTICIPANTS)
+      .map(|i| {
+        (
+          Participant::new(i + 1).unwrap(),
+          <Ristretto as Ciphersuite>::generator() * shares[usize::from(i)],
+        )
+      })
+      .collect::<HashMap<_, _>>();
+    core::array::from_fn(|i| {
+      ThresholdKeys::new(
+        ThresholdParams::new(
+          PARTICIPANTS,
+          PARTICIPANTS,
+          Participant::new(u16::try_from(i + 1).unwrap()).unwrap(),
+        )
+        .unwrap(),
+        Interpolation::Constant(vec![<Ristretto as Ciphersuite>::F::ONE; PARTICIPANTS as usize]),
+        Zeroizing::new(shares[i]),
+        verification_shares.clone(),
+      )
+      .unwrap()
+    })
+  };
+
+  // Perform the promotion
+  let mut promotions = HashMap::new();
+  let mut proofs = HashMap::new();
+  for keys in &keys {
+    let i = keys.params().i();
+    let (promotion, proof) =
+      GeneratorPromotion::<_, AltGenerator<Ristretto>>::promote(&mut OsRng, keys.clone());
+    promotions.insert(i, promotion);
+    proofs.insert(
+      i,
+      GeneratorProof::<Ristretto>::read::<&[u8]>(&mut proof.serialize().as_ref()).unwrap(),
+    );
+  }
+
+  // Complete the promotion, and verify it worked
+  let new_group_key = AltGenerator::<Ristretto>::generator() * *recover_key(&keys).unwrap();
+  for (i, promoting) in promotions.drain() {
+    let promoted = promoting.complete(&clone_without(&proofs, &i)).unwrap();
+    assert_eq!(keys[usize::from(u16::from(i) - 1)].params(), promoted.params());
+    assert_eq!(keys[usize::from(u16::from(i) - 1)].secret_share(), promoted.secret_share());
+    assert_eq!(new_group_key, promoted.group_key());
+    for l in 0 .. PARTICIPANTS {
+      let verification_share =
+        promoted.original_verification_share(Participant::new(l + 1).unwrap());
+      assert_eq!(
+        AltGenerator::<Ristretto>::generator() * **keys[usize::from(l)].secret_share(),
+        verification_share
+      );
+    }
+  }
+}