Add pygost deps

deps/pygost-5.12/build/lib/pygost/utils.py

@@ -0,0 +1,101 @@
+# 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/>.
+
+from codecs import getdecoder
+from codecs import getencoder
+from sys import version_info
+
+
+xrange = range if version_info[0] == 3 else xrange
+
+
+def strxor(a, b):
+    """XOR of two strings
+
+    This function will process only shortest length of both strings,
+    ignoring remaining one.
+    """
+    mlen = min(len(a), len(b))
+    a, b, xor = bytearray(a), bytearray(b), bytearray(mlen)
+    for i in xrange(mlen):
+        xor[i] = a[i] ^ b[i]
+    return bytes(xor)
+
+
+_hexdecoder = getdecoder("hex")
+_hexencoder = getencoder("hex")
+
+
+def hexdec(data):
+    """Decode hexadecimal
+    """
+    return _hexdecoder(data)[0]
+
+
+def hexenc(data):
+    """Encode hexadecimal
+    """
+    return _hexencoder(data)[0].decode("ascii")
+
+
+def bytes2long(raw):
+    """Deserialize big-endian bytes into long number
+
+    :param bytes raw: binary string
+    :returns: deserialized long number
+    :rtype: int
+    """
+    return int(hexenc(raw), 16)
+
+
+def long2bytes(n, size=32):
+    """Serialize long number into big-endian bytestring
+
+    :param long n: long number
+    :returns: serialized bytestring
+    :rtype: bytes
+    """
+    res = hex(int(n))[2:].rstrip("L")
+    if len(res) % 2 != 0:
+        res = "0" + res
+    s = hexdec(res)
+    if len(s) != size:
+        s = (size - len(s)) * b"\x00" + s
+    return s
+
+
+def modinvert(a, n):
+    """Modular multiplicative inverse
+
+    :returns: inverse number. -1 if it does not exist
+
+    Realization is taken from:
+    https://en.wikipedia.org/wiki/Extended_Euclidean_algorithm
+    """
+    if a < 0:
+        # k^-1 = p - (-k)^-1 mod p
+        return n - modinvert(-a, n)
+    t, newt = 0, 1
+    r, newr = n, a
+    while newr != 0:
+        quotinent = r // newr
+        t, newt = newt, t - quotinent * newt
+        r, newr = newr, r - quotinent * newr
+    if r > 1:
+        return -1
+    if t < 0:
+        t = t + n
+    return t