# ===================================================================
#
# Copyright (c) 2021, Legrandin <[email protected]>
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# ===================================================================
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)