PSBT serialize/deserialize impl for EcdsaSig type

src/util/psbt/serialize.rs

@@ -20,7 +20,7 @@
 
 use prelude::*;
 
-use io;
+use ::{EcdsaSig, io};
 
 use blockdata::script::Script;
 use blockdata::transaction::{EcdsaSigHashType, Transaction, TxOut};
@@ -89,6 +89,30 @@ impl Deserialize for PublicKey {
     }
 }
 
+impl Serialize for EcdsaSig {
+    fn serialize(&self) -> Vec<u8> {
+        let mut buf = Vec::with_capacity(72);
+        buf.extend(self.sig.serialize_der().iter());
+        buf.push(self.hash_ty as u8);
+        buf
+    }
+}
+
+impl Deserialize for EcdsaSig {
+    fn deserialize(bytes: &[u8]) -> Result<Self, encode::Error> {
+        let (sighash_byte, signature) = bytes.split_last()
+            .ok_or(encode::Error::ParseFailed("empty partial signature data"))?;
+        Ok(EcdsaSig {
+            sig: secp256k1::ecdsa::Signature::from_der(signature)
+                .map_err(|_| encode::Error::ParseFailed("non-DER encoded signature"))?,
+            // NB: Since BIP-174 says "the signature as would be pushed to the stack from
+            // a scriptSig or witness" we should use a consensus deserialization and do
+            // not error on a non-standard values.
+            hash_ty: EcdsaSigHashType::from_u32_consensus(*sighash_byte as u32)
+        })
+    }
+}
+
 impl Serialize for KeySource {
     fn serialize(&self) -> Vec<u8> {
         let mut rv: Vec<u8> = Vec::with_capacity(key_source_len(&self));