Merge pull request #67 from tuxxy/iterable-signing

Allow iterables to be digested and signed

nkms/crypto/keypairs.py

@@ -1,7 +1,9 @@
 import msgpack
+import sha3
 from random import SystemRandom
 from py_ecc.secp256k1 import N, privtopub, ecdsa_raw_sign, ecdsa_raw_recover
 from npre import umbral
+from typing import Iterable
 
 
 class EncryptingKeypair(object):
@@ -125,6 +127,20 @@ class SigningKeypair(object):
         s = int.from_bytes(sig[2], byteorder='big')
         return (v, r, s)
 
+    def digest(self, *args):
+        """
+        Accepts an iterable containing bytes and digests it.
+
+        :param bytes *args: Data to hash
+
+        :rtype: bytes
+        :return: bytestring of digested data
+        """
+        hash = sha3.keccak_256()
+        for arg in args:
+            hash.update(arg)
+        return hash.digest()
+
     def sign(self, msghash):
         """
         Signs a hashed message and returns a msgpack'ed v, r, and s.

nkms/crypto/keyring.py

@@ -109,12 +109,12 @@ class KeyRing(object):
         """
         Signs a message and returns a signature with the keccak hash.
 
-        :param bytes message: Message to sign in bytes
+        :param Iterable message: Message to sign in an iterable of bytes
 
         :rtype: bytestring
         :return: Signature of message
         """
-        msg_digest = sha3.keccak_256(message).digest()
+        msg_digest = self.sig_keypair.digest(message)
         return self.sig_keypair.sign(msg_digest)
 
     def verify(self, message, signature, pubkey=None):

tests/crypto/test_keypairs.py

@@ -33,6 +33,12 @@ class TestSigningKeypair(unittest.TestCase):
                                            pubkey=self.keypair_a.pub_key)
         self.assertTrue(verify_sig)
 
+    def test_digest(self):
+        digest_a = self.keypair_a.digest(b'foo', b'bar')
+        digest_b = self.keypair_a.digest(b'foobar')
+
+        self.assertEqual(digest_a, digest_b)
+
 
 class TestEncryptingKeypair(unittest.TestCase):
     def setUp(self):

tests/test_network_actors.py

@@ -1,4 +1,5 @@
 import asyncio
+import unittest
 
 from nkms.characters import Ursula, Alice
 from nkms.crypto.keyring import KeyRing
@@ -44,6 +45,7 @@ def test_alice_has_ursulas_public_key_and_uses_it_to_encode_policy_payload():
     policy_group.transmit(networky_stuff)
 
 
+@unittest.skip(reason="Work in progress")
 def test_alice_finds_ursula():
     event_loop = asyncio.new_event_loop()
     asyncio.set_event_loop(event_loop)