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/musig/src/tests.rs

@@ -0,0 +1,70 @@
+use std::collections::HashMap;
+
+use zeroize::Zeroizing;
+use rand_core::OsRng;
+
+use ciphersuite::{group::ff::Field, Ciphersuite, Ristretto};
+
+use dkg_recovery::recover_key;
+use crate::*;
+
+/// Tests MuSig key generation.
+#[test]
+pub fn test_musig() {
+  const PARTICIPANTS: u16 = 5;
+
+  let mut keys = vec![];
+  let mut pub_keys = vec![];
+  for _ in 0 .. PARTICIPANTS {
+    let key = Zeroizing::new(<Ristretto as Ciphersuite>::F::random(&mut OsRng));
+    pub_keys.push(<Ristretto as Ciphersuite>::generator() * *key);
+    keys.push(key);
+  }
+
+  const CONTEXT: [u8; 32] = *b"MuSig Test                      ";
+
+  // Empty signing set
+  musig::<Ristretto>(CONTEXT, Zeroizing::new(<Ristretto as Ciphersuite>::F::ZERO), &[])
+    .unwrap_err();
+  // Signing set we're not part of
+  musig::<Ristretto>(
+    CONTEXT,
+    Zeroizing::new(<Ristretto as Ciphersuite>::F::ZERO),
+    &[<Ristretto as Ciphersuite>::generator()],
+  )
+  .unwrap_err();
+
+  // Test with n keys
+  {
+    let mut created_keys = HashMap::new();
+    let mut verification_shares = HashMap::new();
+    let group_key = musig_key::<Ristretto>(CONTEXT, &pub_keys).unwrap();
+    for (i, key) in keys.iter().enumerate() {
+      let these_keys = musig::<Ristretto>(CONTEXT, key.clone(), &pub_keys).unwrap();
+      assert_eq!(these_keys.params().t(), PARTICIPANTS);
+      assert_eq!(these_keys.params().n(), PARTICIPANTS);
+      assert_eq!(usize::from(u16::from(these_keys.params().i())), i + 1);
+
+      verification_shares.insert(
+        these_keys.params().i(),
+        <Ristretto as Ciphersuite>::generator() * **these_keys.secret_share(),
+      );
+
+      assert_eq!(these_keys.group_key(), group_key);
+
+      created_keys.insert(these_keys.params().i(), these_keys);
+    }
+
+    for keys in created_keys.values() {
+      for (l, verification_share) in &verification_shares {
+        assert_eq!(keys.original_verification_share(*l), *verification_share);
+      }
+    }
+
+    assert_eq!(
+      <Ristretto as Ciphersuite>::generator() *
+        *recover_key(&created_keys.values().cloned().collect::<Vec<_>>()).unwrap(),
+      group_key
+    );
+  }
+}