From fa112a793ac538c82230a4015f45f28ae736c43b Mon Sep 17 00:00:00 2001
From: sanket1729 <sanket1729@gmail.com>
Date: Mon, 15 Nov 2021 12:12:25 -0800
Subject: [PATCH] Add EcdsaSig

---
 src/util/ecdsa.rs | 68 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)

diff --git a/src/util/ecdsa.rs b/src/util/ecdsa.rs
index 33e3685d..1724128a 100644
--- a/src/util/ecdsa.rs
+++ b/src/util/ecdsa.rs
@@ -29,6 +29,8 @@ use hashes::{Hash, hash160};
 use hash_types::{PubkeyHash, WPubkeyHash};
 use util::base58;
 use util::key::Error;
+use blockdata::transaction::SigHashType;
+
 
 /// A Bitcoin ECDSA public key
 #[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
@@ -413,6 +415,72 @@ impl<'de> ::serde::Deserialize<'de> for PublicKey {
     }
 }
 
+/// An ECDSA signature with the corresponding hash type.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+pub struct EcdsaSig {
+    /// The underlying ECDSA Signature
+    pub sig: secp256k1::Signature,
+    /// The corresponding hash type
+    pub hash_ty: SigHashType,
+}
+
+impl EcdsaSig {
+
+    /// Deserialize from slice
+    pub fn from_slice(sl: &[u8]) -> Result<Self, EcdsaSigError> {
+        let (hash_ty, sig) = sl.split_last()
+            .ok_or(EcdsaSigError::EmptySignature)?;
+        let hash_ty = SigHashType::from_u32_standard(*hash_ty as u32)
+            .map_err(|_| EcdsaSigError::NonStandardSigHashType(*hash_ty))?;
+        let sig = secp256k1::Signature::from_der(sig)
+            .map_err(EcdsaSigError::Secp256k1)?;
+        Ok(EcdsaSig { sig, hash_ty })
+    }
+
+    /// Serialize EcdsaSig
+    pub fn to_vec(&self) -> Vec<u8> {
+        // TODO: add support to serialize to a writer to SerializedSig
+        let mut ser_sig = self.sig.serialize_der().to_vec();
+        ser_sig.push(self.hash_ty.as_u32() as u8);
+        ser_sig
+    }
+}
+
+/// A key-related error.
+#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
+pub enum EcdsaSigError {
+    /// Base58 encoding error
+    NonStandardSigHashType(u8),
+    /// Empty Signature
+    EmptySignature,
+    /// secp256k1-related error
+    Secp256k1(secp256k1::Error),
+}
+
+
+impl fmt::Display for EcdsaSigError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match *self {
+            EcdsaSigError::NonStandardSigHashType(hash_ty) =>
+                write!(f, "Non standard signature hash type {}", hash_ty),
+            EcdsaSigError::Secp256k1(ref e) =>
+                write!(f, "Invalid Ecdsa signature: {}", e),
+            EcdsaSigError::EmptySignature =>
+                write!(f, "Empty ECDSA signature"),
+        }
+    }
+}
+
+#[cfg(feature = "std")]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
+impl ::std::error::Error for EcdsaSigError {}
+
+impl From<secp256k1::Error> for EcdsaSigError {
+    fn from(e: secp256k1::Error) -> EcdsaSigError {
+        EcdsaSigError::Secp256k1(e)
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use io;