UKM is actually just a number

[pygost.git] / pygost / gost3410_vko.py

diff --git a/pygost/gost3410_vko.py b/pygost/gost3410_vko.py
index 35cc06f103293625449dfddbdea59814c37685fe..719c4f40f4d17b5ee9ec311354430ba59d0c31b6 100644 (file)
--- a/pygost/gost3410_vko.py
+++ b/pygost/gost3410_vko.py
@@ -24,6 +24,15 @@ from pygost.gost341194 import GOST341194
 from pygost.utils import bytes2long
 
 
+def ukm_unmarshal(ukm):
+    """Unmarshal UKM value
+
+    :type ukm: bytes
+    :rtype: long
+    """
+    return bytes2long(ukm[::-1])
+
+
 def vko_34102001(curve, prv, pubkey, ukm):
     """ Make Diffie-Hellman computation (34.10-2001, 34.11-94)
 
@@ -31,8 +40,7 @@ def vko_34102001(curve, prv, pubkey, ukm):
     :param long prv: private key
     :param pubkey: public key
     :type pubkey: (long, long)
-    :param ukm: UKM value (VKO-factor)
-    :type ukm: bytes, 8 bytes
+    :param long ukm: user keying material, VKO-factor
     :returns: Key Encryption Key (shared key)
     :rtype: bytes, 32 bytes
 
@@ -41,39 +49,37 @@ def vko_34102001(curve, prv, pubkey, ukm):
     hash output.
     """
     key = curve.exp(prv, pubkey[0], pubkey[1])
-    key = curve.exp(bytes2long(24 * b"\x00" + ukm), key[0], key[1])
+    key = curve.exp(ukm, key[0], key[1])
     return GOST341194(pub_marshal(key), "GostR3411_94_CryptoProParamSet").digest()
 
 
-def vko_34102012256(curve, prv, pubkey, ukm=b"\x00\x00\x00\x00\x00\x00\x00\01"):
+def vko_34102012256(curve, prv, pubkey, ukm=1):
     """ Make Diffie-Hellman computation (34.10-2012, 34.11-2012 256 bit)
 
     :param GOST3410Curve curve: curve to use
     :param long prv: private key
     :param pubkey: public key
     :type pubkey: (long, long)
-    :param ukm: UKM value (VKO-factor)
-    :type ukm: bytes, 8 bytes
+    :param long ukm: user keying material, VKO-factor
     :returns: Key Encryption Key (shared key)
     :rtype: bytes, 32 bytes
     """
     key = curve.exp(prv, pubkey[0], pubkey[1])
-    key = curve.exp(bytes2long(ukm[::-1]), key[0], key[1])
+    key = curve.exp(ukm, key[0], key[1])
     return GOST34112012256(pub_marshal(key, mode=2012)).digest()
 
 
-def vko_34102012512(curve, prv, pubkey, ukm=b"\x00\x00\x00\x00\x00\x00\x00\01"):
+def vko_34102012512(curve, prv, pubkey, ukm=1):
     """ Make Diffie-Hellman computation (34.10-2012, 34.11-2012 512 bit)
 
     :param GOST3410Curve curve: curve to use
     :param long prv: private key
     :param pubkey: public key
     :type pubkey: (long, long)
-    :param ukm: UKM value (VKO-factor)
-    :type ukm: bytes, 8 bytes
+    :param long ukm: user keying material, VKO-factor
     :returns: Key Encryption Key (shared key)
     :rtype: bytes, 32 bytes
     """
     key = curve.exp(prv, pubkey[0], pubkey[1])
-    key = curve.exp(bytes2long(ukm[::-1]), key[0], key[1])
+    key = curve.exp(ukm, key[0], key[1])
     return GOST34112012512(pub_marshal(key, mode=2012)).digest()