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# ===================================================================
#
# Copyright (c) 2021, Legrandin <[email protected]>
# 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 . import cSHAKE256
from .TupleHash128 import TupleHash
def new(**kwargs):
"""Create a new TupleHash256 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, cSHAKE256, digest_bytes)
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