Use curve's cofactor during VKO calculations

[pygost.git] / pygost / gost3410_vko.py

diff --git a/pygost/gost3410_vko.py b/pygost/gost3410_vko.py
index e4981afe4f1b470caf69d1785cad0e58bd85b2e1..7bc71113b69e99bcf10dbe2d819d2d8b96361a47 100644 (file)
--- a/pygost/gost3410_vko.py
+++ b/pygost/gost3410_vko.py
@@ -1,11 +1,10 @@
 # coding: utf-8
 # PyGOST -- Pure Python GOST cryptographic functions library
-# Copyright (C) 2015-2017 Sergey Matveev <stargrave@stargrave.org>
+# Copyright (C) 2015-2020 Sergey Matveev <stargrave@stargrave.org>
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
+# the Free Software Foundation, version 3 of the License.
 #
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ -27,7 +26,7 @@ from pygost.utils import bytes2long
 def ukm_unmarshal(ukm):
     """Unmarshal UKM value
 
-    :type ukm: bytes
+    :type ukm: little-endian bytes
     :rtype: long
     """
     return bytes2long(ukm[::-1])
@@ -35,7 +34,7 @@ def ukm_unmarshal(ukm):
 
 def kek(curve, prv, pub, ukm, mode):
     key = curve.exp(prv, pub[0], pub[1])
-    key = curve.exp(ukm, key[0], key[1])
+    key = curve.exp(curve.cofactor * ukm, key[0], key[1])
     return pub_marshal(key, mode)
 
 
@@ -56,11 +55,11 @@ def kek_34102001(curve, prv, pub, ukm):
     """
     return GOST341194(
         kek(curve, prv, pub, ukm, mode=2001),
-        "GostR3411_94_CryptoProParamSet",
+        sbox="id-GostR3411-94-CryptoProParamSet",
     ).digest()
 
 
-def kek_34102012256(curve, prv, pub, ukm=1):
+def kek_34102012256(curve, prv, pub, ukm=1, mode=2012):
     """ Key agreement (34.10-2012, 34.11-2012 256 bit)
 
     :param GOST3410Curve curve: curve to use
@@ -74,7 +73,7 @@ def kek_34102012256(curve, prv, pub, ukm=1):
     Shared Key Encryption Key computation is based on
     :rfc:`7836` VKO GOST R 34.10-2012.
     """
-    return GOST34112012256(kek(curve, prv, pub, ukm, mode=2012)).digest()
+    return GOST34112012256(kek(curve, prv, pub, ukm, mode=mode)).digest()
 
 
 def kek_34102012512(curve, prv, pub, ukm=1):