Pass sigs and associated types by value

We should pass `Copy` types by value not by reference.

Currently this is not done in secp, but lets do it here in bitcoin.

Pass by value:

- `SerializedSignature`
- bitcoin sigs
- secp sigs
- secp `Message`

bitcoin/examples/ecdsa-psbt-simple.rs

@@ -221,7 +221,7 @@ fn main() {
         .enumerate()
         .map(|(idx, input)| {
             let (_, sig) = input.partial_sigs.iter().next().expect("we have one sig");
-            Witness::p2wpkh(sig, pk_inputs[idx].0)
+            Witness::p2wpkh(*sig, pk_inputs[idx].0)
         })
         .collect();
     psbt.inputs.iter_mut().enumerate().for_each(|(idx, input)| {

bitcoin/examples/sighash.rs

@@ -47,7 +47,7 @@ fn compute_sighash_p2wpkh(raw_tx: &[u8], inp_idx: usize, value: u64) {
     let msg = secp256k1::Message::from(sighash);
     println!("Message is {:x}", msg);
     let secp = secp256k1::Secp256k1::verification_only();
-    pk.verify(&secp, &msg, &sig).unwrap()
+    pk.verify(&secp, msg, sig).unwrap()
 }
 
 /// Computes sighash for a legacy multisig transaction input that spends either a p2sh or a p2ms output.

bitcoin/examples/sign-tx-segwit-v0.rs

@@ -75,7 +75,7 @@ fn main() {
     // Update the witness stack.
     let signature = bitcoin::ecdsa::Signature { signature, sighash_type };
     let pk = sk.public_key(&secp);
-    *sighasher.witness_mut(input_index).unwrap() = Witness::p2wpkh(&signature, pk);
+    *sighasher.witness_mut(input_index).unwrap() = Witness::p2wpkh(signature, pk);
 
     // Get the signed transaction.
     let tx = sighasher.into_transaction();

bitcoin/src/blockdata/witness.rs

@@ -243,7 +243,7 @@ impl Witness {
     /// serialized public key. Also useful for spending a P2SH-P2WPKH output.
     ///
     /// It is expected that `pubkey` is related to the secret key used to create `signature`.
-    pub fn p2wpkh(signature: &ecdsa::Signature, pubkey: secp256k1::PublicKey) -> Witness {
+    pub fn p2wpkh(signature: ecdsa::Signature, pubkey: secp256k1::PublicKey) -> Witness {
         let mut witness = Witness::new();
         witness.push_slice(&signature.serialize());
         witness.push_slice(&pubkey.serialize());
@@ -355,7 +355,7 @@ impl Witness {
     /// Pushes, as a new element on the witness, an ECDSA signature.
     ///
     /// Pushes the DER encoded signature + sighash_type, requires an allocation.
-    pub fn push_ecdsa_signature(&mut self, signature: &ecdsa::Signature) {
+    pub fn push_ecdsa_signature(&mut self, signature: ecdsa::Signature) {
         self.push_slice(&signature.serialize())
     }
 
@@ -657,7 +657,7 @@ mod test {
         let signature = secp256k1::ecdsa::Signature::from_der(&sig_bytes).unwrap();
         let mut witness = Witness::default();
         let signature = crate::ecdsa::Signature { signature, sighash_type: EcdsaSighashType::All };
-        witness.push_ecdsa_signature(&signature);
+        witness.push_ecdsa_signature(signature);
         let expected_witness = vec![hex!(
             "304402207c800d698f4b0298c5aac830b822f011bb02df41eb114ade9a6702f364d5e39c0220366900d2a60cab903e77ef7dd415d46509b1f78ac78906e3296f495aa1b1b54101")
             ];

bitcoin/src/crypto/key.rs

@@ -203,10 +203,10 @@ impl PublicKey {
     pub fn verify<C: secp256k1::Verification>(
         &self,
         secp: &Secp256k1<C>,
-        msg: &secp256k1::Message,
-        sig: &ecdsa::Signature,
+        msg: secp256k1::Message,
+        sig: ecdsa::Signature,
     ) -> Result<(), secp256k1::Error> {
-        secp.verify_ecdsa(msg, &sig.signature, &self.inner)
+        secp.verify_ecdsa(&msg, &sig.signature, &self.inner)
     }
 }
 
@@ -336,10 +336,10 @@ impl CompressedPublicKey {
     pub fn verify<C: secp256k1::Verification>(
         &self,
         secp: &Secp256k1<C>,
-        msg: &secp256k1::Message,
-        sig: &ecdsa::Signature,
+        msg: secp256k1::Message,
+        sig: ecdsa::Signature,
     ) -> Result<(), secp256k1::Error> {
-        Ok(secp.verify_ecdsa(msg, &sig.signature, &self.0)?)
+        Ok(secp.verify_ecdsa(&msg, &sig.signature, &self.0)?)
     }
 }
 

bitcoin/src/taproot/serialized_signature.rs

@@ -109,11 +109,11 @@ impl<'a> IntoIterator for &'a SerializedSignature {
 }
 
 impl From<Signature> for SerializedSignature {
-    fn from(value: Signature) -> Self { Self::from_signature(&value) }
+    fn from(value: Signature) -> Self { Self::from_signature(value) }
 }
 
 impl<'a> From<&'a Signature> for SerializedSignature {
-    fn from(value: &'a Signature) -> Self { Self::from_signature(value) }
+    fn from(value: &'a Signature) -> Self { Self::from_signature(*value) }
 }
 
 impl TryFrom<SerializedSignature> for Signature {
@@ -162,7 +162,7 @@ impl SerializedSignature {
     /// Create a SerializedSignature from a Signature.
     /// (this serializes it)
     #[inline]
-    pub fn from_signature(sig: &Signature) -> SerializedSignature { sig.serialize() }
+    pub fn from_signature(sig: Signature) -> SerializedSignature { sig.serialize() }
 
     /// Writes this serialized signature to a `writer`.
     #[inline]