Update secp256k1 dependency

Update our `rust-secp256k1` dependency to the latest version.

Requires doing:

- Add a new variant to `Error` for the case where parity of the internal
  key is an invalid value (not 0 or 1).
- Use non-deprecated const

Cargo.toml

@@ -36,7 +36,7 @@ rustdoc-args = ["--cfg", "docsrs"]
 [dependencies]
 bech32 = { version = "0.8.1", default-features = false }
 bitcoin_hashes = { version = "0.10.0", default-features = false }
-secp256k1 = { version = "0.21.2", default-features = false }
+secp256k1 = { version = "0.22.0", default-features = false }
 core2 = { version = "0.3.0", optional = true, default-features = false }
 
 base64-compat = { version = "1.0.0", optional = true }
@@ -47,7 +47,7 @@ hashbrown = { version = "0.8", optional = true }
 [dev-dependencies]
 serde_json = "<1.0.45"
 serde_test = "1"
-secp256k1 = { version = "0.21.2", features = [ "recovery", "rand-std" ] }
+secp256k1 = { version = "0.22.0", features = [ "recovery", "rand-std" ] }
 bincode = "1.3.1"
 # We need to pin ryu (transitive dep from serde_json) to stay compatible with Rust 1.22.0
 ryu = "<1.0.5"

src/util/schnorr.rs

@@ -174,7 +174,7 @@ impl TweakedPublicKey {
     /// the y-coordinate is represented by only a single bit, as x determines
     /// it up to one bit.
     #[inline]
-    pub fn serialize(&self) -> [u8; constants::SCHNORRSIG_PUBLIC_KEY_SIZE] {
+    pub fn serialize(&self) -> [u8; constants::SCHNORR_PUBLIC_KEY_SIZE] {
         self.0.serialize()
     }
 }

src/util/taproot.rs

@@ -682,7 +682,8 @@ impl ControlBlock {
         {
             return Err(TaprootError::InvalidControlBlockSize(sl.len()));
         }
-        let output_key_parity = secp256k1::Parity::from((sl[0] & 1) as i32);
+        let output_key_parity = secp256k1::Parity::from_i32((sl[0] & 1) as i32)
+            .map_err(TaprootError::InvalidParity)?;
         let leaf_version = LeafVersion::from_consensus(sl[0] & TAPROOT_LEAF_MASK)?;
         let internal_key = UntweakedPublicKey::from_slice(&sl[1..TAPROOT_CONTROL_BASE_SIZE])
             .map_err(TaprootError::InvalidInternalKey)?;
@@ -970,6 +971,8 @@ pub enum TaprootError {
     InvalidControlBlockSize(usize),
     /// Invalid taproot internal key
     InvalidInternalKey(secp256k1::Error),
+    /// Invalid parity for internal key
+    InvalidParity(secp256k1::InvalidParityValue),
     /// Empty TapTree
     EmptyTree,
 }
@@ -999,6 +1002,7 @@ impl fmt::Display for TaprootError {
             ),
             // TODO: add source when in MSRV
             TaprootError::InvalidInternalKey(e) => write!(f, "Invalid Internal XOnly key : {}", e),
+            TaprootError::InvalidParity(e) => write!(f, "Invalid parity value for internal key: {}", e),
             TaprootError::EmptyTree => write!(f, "Taproot Tree must contain at least one script"),
         }
     }