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env/lib/python3.11/site-packages/Crypto/Hash/KMAC128.py

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+# ===================================================================
+#
+# Copyright (c) 2021, Legrandin <helderijs@gmail.com>
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in
+#    the documentation and/or other materials provided with the
+#    distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+# ===================================================================
+
+from binascii import unhexlify
+
+from Crypto.Util.py3compat import bord, tobytes, is_bytes
+from Crypto.Random import get_random_bytes
+
+from . import cSHAKE128, SHA3_256
+from .cSHAKE128 import _bytepad, _encode_str, _right_encode
+
+
+class KMAC_Hash(object):
+    """A KMAC hash object.
+    Do not instantiate directly.
+    Use the :func:`new` function.
+    """
+
+    def __init__(self, data, key, mac_len, custom,
+                 oid_variant, cshake, rate):
+
+        # See https://tools.ietf.org/html/rfc8702
+        self.oid = "2.16.840.1.101.3.4.2." + oid_variant
+        self.digest_size = mac_len
+
+        self._mac = None
+
+        partial_newX = _bytepad(_encode_str(tobytes(key)), rate)
+        self._cshake = cshake._new(partial_newX, custom, b"KMAC")
+
+        if data:
+            self._cshake.update(data)
+
+    def update(self, data):
+        """Authenticate the next chunk of message.
+
+        Args:
+            data (bytes/bytearray/memoryview): The next chunk of the message to
+            authenticate.
+        """
+
+        if self._mac:
+            raise TypeError("You can only call 'digest' or 'hexdigest' on this object")
+
+        self._cshake.update(data)
+        return self
+
+    def digest(self):
+        """Return the **binary** (non-printable) MAC tag of the message.
+
+        :return: The MAC tag. Binary form.
+        :rtype: byte string
+        """
+
+        if not self._mac:
+            self._cshake.update(_right_encode(self.digest_size * 8))
+            self._mac = self._cshake.read(self.digest_size)
+
+        return self._mac
+
+    def hexdigest(self):
+        """Return the **printable** MAC tag of the message.
+
+        :return: The MAC tag. Hexadecimal encoded.
+        :rtype: string
+        """
+
+        return "".join(["%02x" % bord(x) for x in tuple(self.digest())])
+
+    def verify(self, mac_tag):
+        """Verify that a given **binary** MAC (computed by another party)
+        is valid.
+
+        Args:
+          mac_tag (bytes/bytearray/memoryview): the expected MAC of the message.
+
+        Raises:
+            ValueError: if the MAC does not match. It means that the message
+                has been tampered with or that the MAC key is incorrect.
+        """
+
+        secret = get_random_bytes(16)
+
+        mac1 = SHA3_256.new(secret + mac_tag)
+        mac2 = SHA3_256.new(secret + self.digest())
+
+        if mac1.digest() != mac2.digest():
+            raise ValueError("MAC check failed")
+
+    def hexverify(self, hex_mac_tag):
+        """Verify that a given **printable** MAC (computed by another party)
+        is valid.
+
+        Args:
+            hex_mac_tag (string): the expected MAC of the message, as a hexadecimal string.
+
+        Raises:
+            ValueError: if the MAC does not match. It means that the message
+                has been tampered with or that the MAC key is incorrect.
+        """
+
+        self.verify(unhexlify(tobytes(hex_mac_tag)))
+
+    def new(self, **kwargs):
+        """Return a new instance of a KMAC hash object.
+        See :func:`new`.
+        """
+
+        if "mac_len" not in kwargs:
+            kwargs["mac_len"] = self.digest_size
+
+        return new(**kwargs)
+
+
+def new(**kwargs):
+    """Create a new KMAC128 object.
+
+    Args:
+        key (bytes/bytearray/memoryview):
+            The key to use to compute the MAC.
+            It must be at least 128 bits long (16 bytes).
+        data (bytes/bytearray/memoryview):
+            Optional. The very first chunk of the message to authenticate.
+            It is equivalent to an early call to :meth:`KMAC_Hash.update`.
+        mac_len (integer):
+            Optional. The size of the authentication tag, in bytes.
+            Default is 64. Minimum is 8.
+        custom (bytes/bytearray/memoryview):
+            Optional. A customization byte string (``S`` in SP 800-185).
+
+    Returns:
+        A :class:`KMAC_Hash` hash object
+    """
+
+    key = kwargs.pop("key", None)
+    if not is_bytes(key):
+        raise TypeError("You must pass a key to KMAC128")
+    if len(key) < 16:
+        raise ValueError("The key must be at least 128 bits long (16 bytes)")
+
+    data = kwargs.pop("data", None)
+
+    mac_len = kwargs.pop("mac_len", 64)
+    if mac_len < 8:
+        raise ValueError("'mac_len' must be 8 bytes or more")
+
+    custom = kwargs.pop("custom", b"")
+
+    if kwargs:
+        raise TypeError("Unknown parameters: " + str(kwargs))
+
+    return KMAC_Hash(data, key, mac_len, custom, "19", cSHAKE128, 168)