Meaningful changes from aggressive-clippy

I do want to enable a few specific lints, yet aggressive-clippy as a whole
isn't worthwhile.

crypto/dkg/src/encryption.rs

@@ -390,9 +390,10 @@ impl<C: Ciphersuite> Encryption<C> {
     participant: Participant,
     msg: EncryptionKeyMessage<C, M>,
   ) -> M {
-    if self.enc_keys.contains_key(&participant) {
-      panic!("Re-registering encryption key for a participant");
-    }
+    assert!(
+      !self.enc_keys.contains_key(&participant),
+      "Re-registering encryption key for a participant"
+    );
     self.enc_keys.insert(participant, msg.enc_key);
     msg.msg
   }

crypto/dkg/src/frost.rs

@@ -92,7 +92,8 @@ pub struct KeyGenMachine<C: Ciphersuite> {
 
 impl<C: Ciphersuite> KeyGenMachine<C> {
   /// Create a new machine to generate a key.
-  // The context string should be unique among multisigs.
+  ///
+  /// The context string should be unique among multisigs.
   pub fn new(params: ThresholdParams, context: String) -> KeyGenMachine<C> {
     KeyGenMachine { params, context, _curve: PhantomData }
   }
@@ -171,7 +172,6 @@ fn polynomial<F: PrimeField + Zeroize>(
 /// channel.
 ///
 /// If any participant sends multiple secret shares to another participant, they are faulty.
-
 // This should presumably be written as SecretShare(Zeroizing<F::Repr>).
 // It's unfortunately not possible as F::Repr doesn't have Zeroize as a bound.
 // The encryption system also explicitly uses Zeroizing<M> so it can ensure anything being
@@ -353,7 +353,7 @@ impl<C: Ciphersuite> Zeroize for KeyMachine<C> {
   fn zeroize(&mut self) {
     self.params.zeroize();
     self.secret.zeroize();
-    for (_, commitments) in self.commitments.iter_mut() {
+    for commitments in self.commitments.values_mut() {
       commitments.zeroize();
     }
     self.encryption.zeroize();
@@ -499,7 +499,7 @@ impl<C: Ciphersuite> fmt::Debug for BlameMachine<C> {
 
 impl<C: Ciphersuite> Zeroize for BlameMachine<C> {
   fn zeroize(&mut self) {
-    for (_, commitments) in self.commitments.iter_mut() {
+    for commitments in self.commitments.values_mut() {
       commitments.zeroize();
     }
     self.encryption.zeroize();
@@ -536,10 +536,9 @@ impl<C: Ciphersuite> BlameMachine<C> {
       Err(DecryptionError::InvalidProof) => return recipient,
     };
 
-    let share = match Option::<C::F>::from(C::F::from_repr(share_bytes.0)) {
-      Some(share) => share,
+    let Some(share) = Option::<C::F>::from(C::F::from_repr(share_bytes.0)) else {
       // If this isn't a valid scalar, the sender is faulty
-      None => return sender,
+      return sender;
     };
 
     // If this isn't a valid share, the sender is faulty

crypto/dkg/src/tests/mod.rs

@@ -25,7 +25,7 @@ pub const PARTICIPANTS: u16 = 5;
 pub const THRESHOLD: u16 = ((PARTICIPANTS * 2) / 3) + 1;
 
 /// Clone a map without a specific value.
-pub fn clone_without<K: Clone + std::cmp::Eq + std::hash::Hash, V: Clone>(
+pub fn clone_without<K: Clone + core::cmp::Eq + core::hash::Hash, V: Clone>(
   map: &HashMap<K, V>,
   without: &K,
 ) -> HashMap<K, V> {
@@ -40,7 +40,7 @@ pub fn clone_without<K: Clone + std::cmp::Eq + std::hash::Hash, V: Clone>(
 pub fn recover_key<C: Ciphersuite>(keys: &HashMap<Participant, ThresholdKeys<C>>) -> C::F {
   let first = keys.values().next().expect("no keys provided");
   assert!(keys.len() >= first.params().t().into(), "not enough keys provided");
-  let included = keys.keys().cloned().collect::<Vec<_>>();
+  let included = keys.keys().copied().collect::<Vec<_>>();
 
   let group_private = keys.iter().fold(C::F::ZERO, |accum, (i, keys)| {
     accum + (lagrange::<C::F>(*i, &included) * keys.secret_share().deref())

crypto/dkg/src/tests/musig.rs

@@ -24,9 +24,9 @@ pub fn test_musig<R: RngCore + CryptoRng, C: Ciphersuite>(rng: &mut R) {
   const CONTEXT: &[u8] = b"MuSig Test";
 
   // Empty signing set
-  assert!(musig::<C>(CONTEXT, &Zeroizing::new(C::F::ZERO), &[]).is_err());
+  musig::<C>(CONTEXT, &Zeroizing::new(C::F::ZERO), &[]).unwrap_err();
   // Signing set we're not part of
-  assert!(musig::<C>(CONTEXT, &Zeroizing::new(C::F::ZERO), &[C::generator()]).is_err());
+  musig::<C>(CONTEXT, &Zeroizing::new(C::F::ZERO), &[C::generator()]).unwrap_err();
 
   // Test with n keys
   {