82 lines
2.6 KiB
Python
82 lines
2.6 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 derivation functions, Р 50.1.113-2016, Р 1323565.1.020-2018
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"""
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import hmac
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from pygost.gost3410_vko import kek_34102012256
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from pygost.gost3410_vko import kek_34102012512
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from pygost.gost34112012256 import GOST34112012256
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from pygost.utils import bytes2long
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from pygost.utils import long2bytes
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def kdf_gostr3411_2012_256(key, label, seed):
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"""KDF_GOSTR3411_2012_256
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:param bytes key: initial key
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:param bytes label: label
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:param bytes seed: seed
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:returns: 32 bytes
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"""
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return hmac.new(
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key=key,
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msg=b"".join((b"\x01", label, b"\x00", seed, b"\x01\x00")),
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digestmod=GOST34112012256,
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).digest()
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def kdf_tree_gostr3411_2012_256(key, label, seed, keys, i_len=1):
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"""KDF_TREE_GOSTR3411_2012_256
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:param bytes key: initial key
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:param bytes label: label
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:param bytes seed: seed
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:param int keys: number of generated keys
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:param int i_len: length of iterations value (called "R")
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:returns: list of 256-bit keys
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"""
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keymat = []
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_len = long2bytes(keys * 32 * 8, size=1)
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for i in range(keys):
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keymat.append(hmac.new(
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key=key,
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msg=b"".join((long2bytes(i + 1, size=i_len), label, b"\x00", seed, _len)),
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digestmod=GOST34112012256,
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).digest())
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return keymat
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def keg(curve, prv, pub, h):
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"""Export key generation (Р 1323565.1.020-2018)
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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 bytes h: "h"-value, 32 bytes
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"""
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if len(h) != 32:
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raise ValueError("h must be 32 bytes long")
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ukm = bytes2long(h[:16])
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if ukm == 0:
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ukm = 1
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if curve.point_size == 64:
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return kek_34102012512(curve, prv, pub, ukm)
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k_exp = kek_34102012256(curve, prv, pub, ukm)
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return b"".join(kdf_tree_gostr3411_2012_256(k_exp, b"kdf tree", h[16:24], 2))
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