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xmlrpcserver/deps/pygost-5.12/pygost/kdf.py

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+# coding: utf-8
+# PyGOST -- Pure Python GOST cryptographic functions library
+# Copyright (C) 2015-2023 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 derivation functions, Р 50.1.113-2016, Р 1323565.1.020-2018
+"""
+
+import hmac
+
+from pygost.gost3410_vko import kek_34102012256
+from pygost.gost3410_vko import kek_34102012512
+from pygost.gost34112012256 import GOST34112012256
+from pygost.utils import bytes2long
+from pygost.utils import long2bytes
+
+
+def kdf_gostr3411_2012_256(key, label, seed):
+    """KDF_GOSTR3411_2012_256
+
+    :param bytes key: initial key
+    :param bytes label: label
+    :param bytes seed: seed
+    :returns: 32 bytes
+    """
+    return hmac.new(
+        key=key,
+        msg=b"".join((b"\x01", label, b"\x00", seed, b"\x01\x00")),
+        digestmod=GOST34112012256,
+    ).digest()
+
+
+def kdf_tree_gostr3411_2012_256(key, label, seed, keys, i_len=1):
+    """KDF_TREE_GOSTR3411_2012_256
+
+    :param bytes key: initial key
+    :param bytes label: label
+    :param bytes seed: seed
+    :param int keys: number of generated keys
+    :param int i_len: length of iterations value (called "R")
+    :returns: list of 256-bit keys
+    """
+    keymat = []
+    _len = long2bytes(keys * 32 * 8, size=1)
+    for i in range(keys):
+        keymat.append(hmac.new(
+            key=key,
+            msg=b"".join((long2bytes(i + 1, size=i_len), label, b"\x00", seed, _len)),
+            digestmod=GOST34112012256,
+        ).digest())
+    return keymat
+
+
+def keg(curve, prv, pub, h):
+    """Export key generation (Р 1323565.1.020-2018)
+
+    :param GOST3410Curve curve: curve to use
+    :param long prv: private key
+    :param pub: public key
+    :type pub: (long, long)
+    :param bytes h: "h"-value, 32 bytes
+    """
+    if len(h) != 32:
+        raise ValueError("h must be 32 bytes long")
+    ukm = bytes2long(h[:16])
+    if ukm == 0:
+        ukm = 1
+    if curve.point_size == 64:
+        return kek_34102012512(curve, prv, pub, ukm)
+    k_exp = kek_34102012256(curve, prv, pub, ukm)
+    return b"".join(kdf_tree_gostr3411_2012_256(k_exp, b"kdf tree", h[16:24], 2))