98 lines
3.1 KiB
Python
98 lines
3.1 KiB
Python
# coding: utf-8
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# PyGOST -- Pure Python GOST cryptographic functions library
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# Copyright (C) 2015-2023 Sergey Matveev <stargrave@stargrave.org>
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, version 3 of the License.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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"""Key agreement functions, VKO GOST R 34.10-2001/2012
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"""
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from pygost.gost3410 import pub_marshal
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from pygost.gost34112012256 import GOST34112012256
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from pygost.gost34112012512 import GOST34112012512
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from pygost.gost341194 import GOST341194
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from pygost.utils import bytes2long
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def ukm_unmarshal(ukm):
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"""Unmarshal UKM value
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:type ukm: little-endian bytes
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:rtype: long
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"""
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return bytes2long(ukm[::-1])
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def kek(curve, prv, pub, ukm, mask=None):
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if not curve.contains(pub):
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raise ValueError("pub is not on the curve")
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key = curve.exp(prv, pub[0], pub[1])
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key = curve.exp(curve.cofactor * ukm, key[0], key[1])
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if mask is not None:
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key = curve.exp(mask, key[0], key[1])
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return pub_marshal(key)
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def kek_34102001(curve, prv, pub, ukm):
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"""Key agreement (34.10-2001, 34.11-94)
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:param GOST3410Curve curve: curve to use
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:param long prv: private key
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:param pub: public key
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:type pub: (long, long)
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:param long ukm: user keying material, VKO-factor
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:returns: Key Encryption Key (shared key)
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:rtype: bytes, 32 bytes
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Shared Key Encryption Key computation is based on
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:rfc:`4357` VKO GOST R 34.10-2001 with little-endian
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hash output.
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"""
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return GOST341194(
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kek(curve, prv, pub, ukm),
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sbox="id-GostR3411-94-CryptoProParamSet",
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).digest()
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def kek_34102012256(curve, prv, pub, ukm=1):
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"""Key agreement (34.10-2012, 34.11-2012 256 bit)
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:param GOST3410Curve curve: curve to use
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:param long prv: private key
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:param pub: public key
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:type pub: (long, long)
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:param long ukm: user keying material, VKO-factor
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:returns: Key Encryption Key (shared key)
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:rtype: bytes, 32 bytes
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Shared Key Encryption Key computation is based on
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:rfc:`7836` VKO GOST R 34.10-2012.
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"""
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return GOST34112012256(kek(curve, prv, pub, ukm)).digest()
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def kek_34102012512(curve, prv, pub, ukm=1):
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"""Key agreement (34.10-2012, 34.11-2012 512 bit)
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:param GOST3410Curve curve: curve to use
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:param long prv: private key
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:param pub: public key
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:type pub: (long, long)
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:param long ukm: user keying material, VKO-factor
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:returns: Key Encryption Key (shared key)
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:rtype: bytes, 32 bytes
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Shared Key Encryption Key computation is based on
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:rfc:`7836` VKO GOST R 34.10-2012.
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"""
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return GOST34112012512(kek(curve, prv, pub, ukm)).digest()
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