2 # PyGOST -- Pure Python GOST cryptographic functions library
3 # Copyright (C) 2015-2016 Sergey Matveev <stargrave@stargrave.org>
5 # This program is free software: you can redistribute it and/or modify
6 # it under the terms of the GNU General Public License as published by
7 # the Free Software Foundation, either version 3 of the License, or
8 # (at your option) any later version.
10 # This program is distributed in the hope that it will be useful,
11 # but WITHOUT ANY WARRANTY; without even the implied warranty of
12 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 # GNU General Public License for more details.
15 # You should have received a copy of the GNU General Public License
16 # along with this program. If not, see <http://www.gnu.org/licenses/>.
17 """Diffie-Hellman functions, VKO GOST R 34.10-2001/2012
20 from pygost.gost3410 import pub_marshal
21 from pygost.gost34112012256 import GOST34112012256
22 from pygost.gost34112012512 import GOST34112012512
23 from pygost.gost341194 import GOST341194
24 from pygost.utils import bytes2long
27 def ukm_unmarshal(ukm):
28 """Unmarshal UKM value
33 return bytes2long(ukm[::-1])
36 def kek_34102001(curve, prv, pubkey, ukm):
37 """ Make Diffie-Hellman computation (34.10-2001, 34.11-94)
39 :param GOST3410Curve curve: curve to use
40 :param long prv: private key
41 :param pubkey: public key
42 :type pubkey: (long, long)
43 :param long ukm: user keying material, VKO-factor
44 :returns: Key Encryption Key (shared key)
45 :rtype: bytes, 32 bytes
47 Shared Key Encryption Key computation is based on
48 :rfc:`4357` VKO GOST R 34.10-2001 with little-endian
51 key = curve.exp(prv, pubkey[0], pubkey[1])
52 key = curve.exp(ukm, key[0], key[1])
53 return GOST341194(pub_marshal(key), "GostR3411_94_CryptoProParamSet").digest()
56 def kek_34102012256(curve, prv, pubkey, ukm=1):
57 """ Make Diffie-Hellman computation (34.10-2012, 34.11-2012 256 bit)
59 :param GOST3410Curve curve: curve to use
60 :param long prv: private key
61 :param pubkey: public key
62 :type pubkey: (long, long)
63 :param long ukm: user keying material, VKO-factor
64 :returns: Key Encryption Key (shared key)
65 :rtype: bytes, 32 bytes
67 key = curve.exp(prv, pubkey[0], pubkey[1])
68 key = curve.exp(ukm, key[0], key[1])
69 return GOST34112012256(pub_marshal(key, mode=2012)).digest()
72 def kek_34102012512(curve, prv, pubkey, ukm=1):
73 """ Make Diffie-Hellman computation (34.10-2012, 34.11-2012 512 bit)
75 :param GOST3410Curve curve: curve to use
76 :param long prv: private key
77 :param pubkey: public key
78 :type pubkey: (long, long)
79 :param long ukm: user keying material, VKO-factor
80 :returns: Key Encryption Key (shared key)
81 :rtype: bytes, 32 bytes
83 key = curve.exp(prv, pubkey[0], pubkey[1])
84 key = curve.exp(ukm, key[0], key[1])
85 return GOST34112012512(pub_marshal(key, mode=2012)).digest()