+# coding: utf-8
+# PyGOST -- Pure Python GOST cryptographic functions library
+# 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, 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
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+"""Key agreement functions, VKO GOST R 34.10-2001/2012
+"""
+
from pygost.gost3410 import pub_marshal
-from pygost.gost3411_2012_256 import GOST34112012256
-from pygost.gost3411_2012_512 import GOST34112012512
-from pygost.gost3411_94 import GOST341194
+from pygost.gost34112012256 import GOST34112012256
+from pygost.gost34112012512 import GOST34112012512
+from pygost.gost341194 import GOST341194
from pygost.utils import bytes2long
-def vko_34102001(curve, private_key, pubkey, ukm):
- """ Make Diffie-Hellman computation (34.10-2001, 34.11-94)
+def ukm_unmarshal(ukm):
+ """Unmarshal UKM value
+
+ :type ukm: little-endian bytes
+ :rtype: long
+ """
+ return bytes2long(ukm[::-1])
+
+
+def kek(curve, prv, pub, ukm, mode):
+ key = curve.exp(prv, pub[0], pub[1])
+ key = curve.exp(curve.cofactor * ukm, key[0], key[1])
+ return pub_marshal(key, mode)
+
+
+def kek_34102001(curve, prv, pub, ukm):
+ """ Key agreement (34.10-2001, 34.11-94)
:param GOST3410Curve curve: curve to use
- :param long private_key: private key
- :param ukm: UKM value (VKO-factor)
- :type ukm: bytes, 8 bytes
- :param pubkey: public key's part
- :type pubkey: (long, long)
- :return: Key Encryption Key (shared key)
+ :param long prv: private key
+ :param pub: public key
+ :type pub: (long, long)
+ :param long ukm: user keying material, VKO-factor
+ :returns: Key Encryption Key (shared key)
:rtype: bytes, 32 bytes
Shared Key Encryption Key computation is based on
- :rfc:`4357` VKO GOST 34.10-2001 with little-endian
+ :rfc:`4357` VKO GOST R 34.10-2001 with little-endian
hash output.
"""
- key = curve.exp(private_key, pubkey[0], pubkey[1])
- key = curve.exp(bytes2long(24 * b"\x00" + ukm), key[0], key[1])
- return GOST341194(pub_marshal(key), "GostR3411_94_CryptoProParamSet").digest()
+ return GOST341194(
+ kek(curve, prv, pub, ukm, mode=2001),
+ sbox="id-GostR3411-94-CryptoProParamSet",
+ ).digest()
-def vko_34102012256(curve, private_key, pubkey, ukm=b"\x00\x00\x00\x00\x00\x00\x00\01"):
- """ Make Diffie-Hellman computation (34.10-2012, 34.11-2012 256 bit)
+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
- :param long private_key: private key
- :param ukm: UKM value (VKO-factor)
- :type ukm: bytes, 8 bytes
- :param pubkey: public key's part
- :type pubkey: (long, long)
- :return: Key Encryption Key (shared key)
+ :param long prv: private key
+ :param pub: public key
+ :type pub: (long, long)
+ :param long ukm: user keying material, VKO-factor
+ :returns: Key Encryption Key (shared key)
:rtype: bytes, 32 bytes
+
+ Shared Key Encryption Key computation is based on
+ :rfc:`7836` VKO GOST R 34.10-2012.
"""
- key = curve.exp(private_key, pubkey[0], pubkey[1])
- key = curve.exp(bytes2long(ukm[::-1]), key[0], key[1])
- return GOST34112012256(pub_marshal(key, mode=2012)).digest()
+ return GOST34112012256(kek(curve, prv, pub, ukm, mode=mode)).digest()
-def vko_34102012512(curve, private_key, pubkey, ukm=b"\x00\x00\x00\x00\x00\x00\x00\01"):
- """ Make Diffie-Hellman computation (34.10-2012, 34.11-2012 512 bit)
+def kek_34102012512(curve, prv, pub, ukm=1):
+ """ Key agreement (34.10-2012, 34.11-2012 512 bit)
:param GOST3410Curve curve: curve to use
- :param long private_key: private key
- :param ukm: UKM value (VKO-factor)
- :type ukm: bytes, 8 bytes
- :param pubkey: public key's part
- :type pubkey: (long, long)
- :return: Key Encryption Key (shared key)
+ :param long prv: private key
+ :param pub: public key
+ :type pub: (long, long)
+ :param long ukm: user keying material, VKO-factor
+ :returns: Key Encryption Key (shared key)
:rtype: bytes, 32 bytes
+
+ Shared Key Encryption Key computation is based on
+ :rfc:`7836` VKO GOST R 34.10-2012.
"""
- key = curve.exp(private_key, pubkey[0], pubkey[1])
- key = curve.exp(bytes2long(ukm[::-1]), key[0], key[1])
- return GOST34112012512(pub_marshal(key, mode=2012)).digest()
+ return GOST34112012512(kek(curve, prv, pub, ukm, mode=2012)).digest()