70 lines
2.8 KiB
Python
70 lines
2.8 KiB
Python
# ===================================================================
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#
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# Copyright (c) 2021, Legrandin <helderijs@gmail.com>
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# All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions
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# are met:
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#
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# 1. Redistributions of source code must retain the above copyright
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# notice, this list of conditions and the following disclaimer.
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# 2. Redistributions in binary form must reproduce the above copyright
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# notice, this list of conditions and the following disclaimer in
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# the documentation and/or other materials provided with the
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# distribution.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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# COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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# POSSIBILITY OF SUCH DAMAGE.
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# ===================================================================
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from . import cSHAKE256
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from .TupleHash128 import TupleHash
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def new(**kwargs):
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"""Create a new TupleHash256 object.
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Args:
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digest_bytes (integer):
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Optional. The size of the digest, in bytes.
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Default is 64. Minimum is 8.
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digest_bits (integer):
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Optional and alternative to ``digest_bytes``.
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The size of the digest, in bits (and in steps of 8).
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Default is 512. Minimum is 64.
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custom (bytes):
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Optional.
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A customization bytestring (``S`` in SP 800-185).
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:Return: A :class:`TupleHash` object
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"""
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digest_bytes = kwargs.pop("digest_bytes", None)
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digest_bits = kwargs.pop("digest_bits", None)
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if None not in (digest_bytes, digest_bits):
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raise TypeError("Only one digest parameter must be provided")
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if (None, None) == (digest_bytes, digest_bits):
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digest_bytes = 64
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if digest_bytes is not None:
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if digest_bytes < 8:
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raise ValueError("'digest_bytes' must be at least 8")
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else:
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if digest_bits < 64 or digest_bits % 8:
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raise ValueError("'digest_bytes' must be at least 64 "
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"in steps of 8")
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digest_bytes = digest_bits // 8
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custom = kwargs.pop("custom", b'')
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return TupleHash(custom, cSHAKE256, digest_bytes)
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