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xmlrpcserver/deps/pygost-5.12/pygost/gost28147_mac.py

@@ -0,0 +1,99 @@
+# 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/>.
+"""GOST 28147-89 MAC
+"""
+
+from copy import copy
+
+from pygost.gost28147 import block2ns
+from pygost.gost28147 import BLOCKSIZE
+from pygost.gost28147 import DEFAULT_SBOX
+from pygost.gost28147 import ns2block
+from pygost.gost28147 import validate_iv
+from pygost.gost28147 import validate_key
+from pygost.gost28147 import validate_sbox
+from pygost.gost28147 import xcrypt
+from pygost.gost3413 import pad1
+from pygost.iface import PEP247
+from pygost.utils import strxor
+from pygost.utils import xrange
+
+digest_size = 8
+SEQ_MAC = (
+    0, 1, 2, 3, 4, 5, 6, 7,
+    0, 1, 2, 3, 4, 5, 6, 7,
+)
+
+
+class MAC(PEP247):
+    """GOST 28147-89 MAC mode of operation
+
+    >>> m = MAC(key=key)
+    >>> m.update("some data")
+    >>> m.update("another data")
+    >>> m.hexdigest()[:8]
+    'a687a08b'
+    """
+    digest_size = digest_size
+
+    def __init__(self, key, data=b"", iv=8 * b"\x00", sbox=DEFAULT_SBOX):
+        """
+        :param key: authentication key
+        :type key: bytes, 32 bytes
+        :param iv: initialization vector
+        :type iv: bytes, BLOCKSIZE length
+        :param sbox: S-box parameters to use
+        :type sbox: str, SBOXES'es key
+        """
+        validate_key(key)
+        validate_iv(iv)
+        validate_sbox(sbox)
+        self.key = key
+        self.data = data
+        self.iv = iv
+        self.sbox = sbox
+
+    def copy(self):
+        return MAC(self.key, copy(self.data), self.iv, self.sbox)
+
+    def update(self, data):
+        """Append data that has to be authenticated
+        """
+        self.data += data
+
+    def digest(self):
+        """Get MAC tag of supplied data
+
+        You have to provide at least single byte of data.
+        If you want to produce tag length of 3 bytes, then
+        ``digest()[:3]``.
+        """
+        if not self.data:
+            raise ValueError("No data processed")
+        data = pad1(self.data, BLOCKSIZE)
+        prev = block2ns(self.iv)[::-1]
+        for i in xrange(0, len(data), BLOCKSIZE):
+            prev = xcrypt(
+                SEQ_MAC, self.sbox, self.key, block2ns(strxor(
+                    data[i:i + BLOCKSIZE],
+                    ns2block(prev),
+                )),
+            )[::-1]
+        return ns2block(prev)
+
+
+def new(key, data=b"", iv=8 * b"\x00", sbox=DEFAULT_SBOX):
+    return MAC(key, data, iv, sbox)