refactor

cashu/core/secp.py

@@ -0,0 +1,52 @@
+from secp256k1 import PrivateKey, PublicKey
+
+
+# We extend the public key to define some operations on points
+# Picked from https://github.com/WTRMQDev/secp256k1-zkp-py/blob/master/secp256k1_zkp/__init__.py
+class PublicKeyExt(PublicKey):
+    def __add__(self, pubkey2):
+        if isinstance(pubkey2, PublicKey):
+            new_pub = PublicKey()
+            new_pub.combine([self.public_key, pubkey2.public_key])
+            return new_pub
+        else:
+            raise TypeError("Cant add pubkey and %s" % pubkey2.__class__)
+
+    def __neg__(self):
+        serialized = self.serialize()
+        first_byte, remainder = serialized[:1], serialized[1:]
+        # flip odd/even byte
+        first_byte = {b"\x03": b"\x02", b"\x02": b"\x03"}[first_byte]
+        return PublicKey(first_byte + remainder, raw=True)
+
+    def __sub__(self, pubkey2):
+        if isinstance(pubkey2, PublicKey):
+            return self + (-pubkey2)
+        else:
+            raise TypeError("Can't add pubkey and %s" % pubkey2.__class__)
+
+    def mult(self, privkey):
+        if isinstance(privkey, PrivateKey):
+            return self.tweak_mul(privkey.private_key)
+        else:
+            raise TypeError("Can't multiply with non privatekey")
+
+    def __eq__(self, pubkey2):
+        if isinstance(pubkey2, PublicKey):
+            seq1 = self.to_data()
+            seq2 = pubkey2.to_data()
+            return seq1 == seq2
+        else:
+            raise TypeError("Can't compare pubkey and %s" % pubkey2.__class__)
+
+    def to_data(self):
+        return [self.public_key.data[i] for i in range(64)]
+
+
+# Horrible monkeypatching
+PublicKey.__add__ = PublicKeyExt.__add__
+PublicKey.__neg__ = PublicKeyExt.__neg__
+PublicKey.__sub__ = PublicKeyExt.__sub__
+PublicKey.mult = PublicKeyExt.mult
+PublicKey.__eq__ = PublicKeyExt.__eq__
+PublicKey.to_data = PublicKeyExt.to_data