X-Git-Url: http://www.git.cypherpunks.ru/?a=blobdiff_plain;f=pygost%2Fgost28147.py;h=b7fc0f46634d5589cb41b3bdef10feff8d2e4c84;hb=744398c0b6a3ab223d91cbf56a72932a7c87381d;hp=a6a819f8bb4a5efa378e887b6204c9f82bcb9fc6;hpb=0fcc8bc147ada51d2a9a912f18ac362d54b7d49a;p=pygost.git

diff --git a/pygost/gost28147.py b/pygost/gost28147.py
index a6a819f..b7fc0f4 100644
--- a/pygost/gost28147.py
+++ b/pygost/gost28147.py
@@ -1,11 +1,10 @@
 # coding: utf-8
 # PyGOST -- Pure Python GOST cryptographic functions library
-# Copyright (C) 2015-2019 Sergey Matveev <stargrave@stargrave.org>
+# 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, either version 3 of the License, or
-# (at your option) any later version.
+# 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
@@ -29,7 +28,7 @@ from pygost.gost3413 import pad_size
 from pygost.gost3413 import unpad2
 from pygost.utils import hexdec
 from pygost.utils import strxor
-from pygost.utils import xrange  # pylint: disable=redefined-builtin
+from pygost.utils import xrange
 
 
 KEYSIZE = 32
@@ -182,18 +181,11 @@ def ns2block(ns):
     """
     n1, n2 = ns
     return bytes(bytearray((
-        (n2 >> 0) & 255, (n2 >> 8) & 255, (n2 >> 16) & 255, (n2 >> 24) & 255,
-        (n1 >> 0) & 255, (n1 >> 8) & 255, (n1 >> 16) & 255, (n1 >> 24) & 255,
+        (n2 >> 0) & 0xFF, (n2 >> 8) & 0xFF, (n2 >> 16) & 0xFF, (n2 >> 24) & 0xFF,
+        (n1 >> 0) & 0xFF, (n1 >> 8) & 0xFF, (n1 >> 16) & 0xFF, (n1 >> 24) & 0xFF,
     )))
 
 
-def addmod(x, y, mod=2 ** 32):
-    """ Modulo adding of two integers
-    """
-    r = x + y
-    return r if r < mod else r - mod
-
-
 def _shift11(x):
     """ 11-bit cyclic shift
     """
@@ -237,7 +229,7 @@ def xcrypt(seq, sbox, key, ns):
     ]
     n1, n2 = ns
     for i in seq:
-        n1, n2 = _shift11(_K(s, addmod(n1, x[i]))) ^ n2, n1
+        n1, n2 = _shift11(_K(s, (n1 + x[i]) % (2 ** 32))) ^ n2, n1
     return n1, n2
 
 
@@ -374,8 +366,8 @@ def cnt(key, data, iv=8 * b"\x00", sbox=DEFAULT_SBOX):
     n2, n1 = encrypt(sbox, key, block2ns(iv))
     gamma = []
     for _ in xrange(0, len(data) + pad_size(len(data), BLOCKSIZE), BLOCKSIZE):
-        n1 = addmod(n1, C2, 2 ** 32)
-        n2 = addmod(n2, C1, 2 ** 32 - 1)
+        n1 = (n1 + C2) % (2 ** 32)
+        n2 = (n2 + C1) % (2 ** 32 - 1)
         gamma.append(ns2block(encrypt(sbox, key, (n1, n2))))
     return strxor(b"".join(gamma), data)