Edit File: TupleHash128.py
# =================================================================== # # 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 byte string in the tuple. Args: data (bytes/bytearray/memoryview): The next byte string. """ if self._digest is not None: raise TypeError("You cannot call 'update' after 'digest' or 'hexdigest'") if not is_bytes(data): raise TypeError("You can only call 'update' on bytes") self._cshake.update(_encode_str(tobytes(data))) 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'') if kwargs: raise TypeError("Unknown parameters: " + str(kwargs)) return TupleHash(custom, cSHAKE128, digest_bytes)
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