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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 Crypto.Util.py3compat import bord, is_bytes, tobytes
- from . import cSHAKE128
- from .cSHAKE128 import _encode_str, _right_encode
- class TupleHash(object):
- """A Tuple hash object.
- Do not instantiate directly.
- Use the :func:`new` function.
- """
- def __init__(self, custom, cshake, digest_size):
- self.digest_size = digest_size
- self._cshake = cshake._new(b'', custom, b'TupleHash')
- self._digest = None
- def update(self, *data):
- """Authenticate the next tuple of byte strings.
- TupleHash guarantees the logical separation between each byte string.
- Args:
- data (bytes/bytearray/memoryview): One or more items to hash.
- """
- if self._digest is not None:
- raise TypeError("You cannot call 'update' after 'digest' or 'hexdigest'")
- for item in data:
- if not is_bytes(item):
- raise TypeError("You can only call 'update' on bytes" )
- self._cshake.update(_encode_str(item))
- return self
- def digest(self):
- """Return the **binary** (non-printable) digest of the tuple of byte strings.
- :return: The hash digest. Binary form.
- :rtype: byte string
- """
- if self._digest is None:
- self._cshake.update(_right_encode(self.digest_size * 8))
- self._digest = self._cshake.read(self.digest_size)
- return self._digest
- def hexdigest(self):
- """Return the **printable** digest of the tuple of byte strings.
- :return: The hash digest. Hexadecimal encoded.
- :rtype: string
- """
- return "".join(["%02x" % bord(x) for x in tuple(self.digest())])
- def new(self, **kwargs):
- """Return a new instance of a TupleHash object.
- See :func:`new`.
- """
- if "digest_bytes" not in kwargs and "digest_bits" not in kwargs:
- kwargs["digest_bytes"] = self.digest_size
- return new(**kwargs)
- def new(**kwargs):
- """Create a new TupleHash128 object.
- Args:
- digest_bytes (integer):
- Optional. The size of the digest, in bytes.
- Default is 64. Minimum is 8.
- digest_bits (integer):
- Optional and alternative to ``digest_bytes``.
- The size of the digest, in bits (and in steps of 8).
- Default is 512. Minimum is 64.
- custom (bytes):
- Optional.
- A customization bytestring (``S`` in SP 800-185).
- :Return: A :class:`TupleHash` object
- """
- digest_bytes = kwargs.pop("digest_bytes", None)
- digest_bits = kwargs.pop("digest_bits", None)
- if None not in (digest_bytes, digest_bits):
- raise TypeError("Only one digest parameter must be provided")
- if (None, None) == (digest_bytes, digest_bits):
- digest_bytes = 64
- if digest_bytes is not None:
- if digest_bytes < 8:
- raise ValueError("'digest_bytes' must be at least 8")
- else:
- if digest_bits < 64 or digest_bits % 8:
- raise ValueError("'digest_bytes' must be at least 64 "
- "in steps of 8")
- digest_bytes = digest_bits // 8
- custom = kwargs.pop("custom", b'')
- return TupleHash(custom, cSHAKE128, digest_bytes)
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