refactor: sign messages eip191 (#176)

Author: alexbarnsley

crypto/utils/message.py

@@ -7,6 +7,8 @@
 from crypto.identity.private_key import PrivateKey
 from crypto.identity.public_key import PublicKey
 
+MESSAGE_PREFIX = b"\x19Ethereum Signed Message:\n"
+
 class Message(object):
     public_key: bytes
     message: bytes
@@ -62,9 +64,9 @@ def sign(cls, message: Union[bytes, str], passphrase: Union[bytes, str]):
         private_key = PrivateKey.from_passphrase(passphrase)
         public_key = private_key.public_key
 
-        transaction_signature = private_key.sign(message)
+        transaction_signature = private_key.sign(MESSAGE_PREFIX + (str(len(message))).encode() + message)
 
-        signature_v = bytes([transaction_signature[0]]).hex()
+        signature_v = bytes([int(transaction_signature[0]) + 27]).hex()
         signature_r = transaction_signature[1:33].hex()
         signature_s = transaction_signature[33:].hex()
 
@@ -84,13 +86,15 @@ def verify(self):
         """
 
         signature = unhexlify(self.signature)
-        message_hash = keccak.new(data=self.message, digest_bits=256).digest()
+
+        message = MESSAGE_PREFIX + (str(len(self.message))).encode() + self.message
+        message_hash = keccak.new(data=message, digest_bits=256).digest()
 
         signature_r = signature[0:32]
         signature_s = signature[32:64]
         signature_v = signature[64]
 
-        signature = signature_r + signature_s + bytes([signature_v])
+        signature = signature_r + signature_s + bytes([signature_v - 27])
 
         public_key = PublicKey.recover(message_hash, signature)
 

tests/fixtures/message-sign.json

@@ -1,5 +1,5 @@
 {
 	"message": "Hello, world!",
 	"publicKey": "0243333347c8cbf4e3cbc7a96964181d02a2b0c854faa2fef86b4b8d92afcf473d",
-	"signature": "0e2e53409be748834cac44052817ecef569b429a0492aa6bbc0d934eb71a09547e77aeef33d45669bbcba0498149f0e2b637fe8905186e08a5410c6f2b013bb400"
+	"signature": "0x2bdd0c58ff8a25f456065fb731c73308a25d0a09f351f23e3c7dd3882776d33d626b0cafc0b99dd7504b24f6ecd2e036a267c8e5e005f36dcbc03b2e33fa7fc31c"
 }

tests/utils/test_message.py

@@ -7,7 +7,7 @@ def test_verify_with_publicKey(load_transaction_fixture):
 
     result = Message(
         message=fixture['message'],
-        signature=fixture['signature'],
+        signature=fixture['signature'][2:],
         public_key=fixture['publicKey'],
     )
 
@@ -20,7 +20,7 @@ def test_message_sign_verification(load_transaction_fixture, passphrase):
 
     message: Message = Message.sign(fixture['message'], passphrase)
 
-    assert message.signature.decode() == fixture['signature']
+    assert message.signature.decode() == fixture['signature'][2:]
     assert message.public_key.decode() == fixture['publicKey']
     assert message.message.decode() == fixture['message']