248 lines
9.2 KiB
Python
248 lines
9.2 KiB
Python
# ===================================================================
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#
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# Copyright (c) 2014, 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 binascii import unhexlify
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from Cryptodome.Util.py3compat import bord, tobytes
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from Cryptodome.Random import get_random_bytes
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from Cryptodome.Util._raw_api import (load_pycryptodome_raw_lib,
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VoidPointer, SmartPointer,
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create_string_buffer,
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get_raw_buffer, c_size_t,
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c_uint8_ptr)
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_raw_blake2b_lib = load_pycryptodome_raw_lib("Cryptodome.Hash._BLAKE2b",
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"""
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int blake2b_init(void **state,
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const uint8_t *key,
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size_t key_size,
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size_t digest_size);
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int blake2b_destroy(void *state);
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int blake2b_update(void *state,
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const uint8_t *buf,
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size_t len);
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int blake2b_digest(const void *state,
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uint8_t digest[64]);
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int blake2b_copy(const void *src, void *dst);
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""")
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class BLAKE2b_Hash(object):
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"""A BLAKE2b hash object.
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Do not instantiate directly. Use the :func:`new` function.
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:ivar oid: ASN.1 Object ID
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:vartype oid: string
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:ivar block_size: the size in bytes of the internal message block,
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input to the compression function
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:vartype block_size: integer
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:ivar digest_size: the size in bytes of the resulting hash
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:vartype digest_size: integer
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"""
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# The internal block size of the hash algorithm in bytes.
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block_size = 64
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def __init__(self, data, key, digest_bytes, update_after_digest):
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# The size of the resulting hash in bytes.
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self.digest_size = digest_bytes
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self._update_after_digest = update_after_digest
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self._digest_done = False
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# See https://tools.ietf.org/html/rfc7693
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if digest_bytes in (20, 32, 48, 64) and not key:
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self.oid = "1.3.6.1.4.1.1722.12.2.1." + str(digest_bytes)
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state = VoidPointer()
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result = _raw_blake2b_lib.blake2b_init(state.address_of(),
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c_uint8_ptr(key),
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c_size_t(len(key)),
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c_size_t(digest_bytes)
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)
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if result:
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raise ValueError("Error %d while instantiating BLAKE2b" % result)
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self._state = SmartPointer(state.get(),
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_raw_blake2b_lib.blake2b_destroy)
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if data:
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self.update(data)
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def update(self, data):
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"""Continue hashing of a message by consuming the next chunk of data.
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Args:
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data (bytes/bytearray/memoryview): The next chunk of the message being hashed.
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"""
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if self._digest_done and not self._update_after_digest:
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raise TypeError("You can only call 'digest' or 'hexdigest' on this object")
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result = _raw_blake2b_lib.blake2b_update(self._state.get(),
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c_uint8_ptr(data),
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c_size_t(len(data)))
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if result:
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raise ValueError("Error %d while hashing BLAKE2b data" % result)
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return self
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def digest(self):
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"""Return the **binary** (non-printable) digest of the message that has been hashed so far.
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:return: The hash digest, computed over the data processed so far.
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Binary form.
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:rtype: byte string
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"""
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bfr = create_string_buffer(64)
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result = _raw_blake2b_lib.blake2b_digest(self._state.get(),
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bfr)
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if result:
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raise ValueError("Error %d while creating BLAKE2b digest" % result)
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self._digest_done = True
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return get_raw_buffer(bfr)[:self.digest_size]
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def hexdigest(self):
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"""Return the **printable** digest of the message that has been hashed so far.
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:return: The hash digest, computed over the data processed so far.
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Hexadecimal encoded.
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:rtype: string
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"""
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return "".join(["%02x" % bord(x) for x in tuple(self.digest())])
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def verify(self, mac_tag):
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"""Verify that a given **binary** MAC (computed by another party)
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is valid.
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Args:
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mac_tag (bytes/bytearray/memoryview): the expected MAC of the message.
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Raises:
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ValueError: if the MAC does not match. It means that the message
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has been tampered with or that the MAC key is incorrect.
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"""
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secret = get_random_bytes(16)
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mac1 = new(digest_bits=160, key=secret, data=mac_tag)
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mac2 = new(digest_bits=160, key=secret, data=self.digest())
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if mac1.digest() != mac2.digest():
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raise ValueError("MAC check failed")
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def hexverify(self, hex_mac_tag):
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"""Verify that a given **printable** MAC (computed by another party)
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is valid.
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Args:
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hex_mac_tag (string): the expected MAC of the message, as a hexadecimal string.
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Raises:
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ValueError: if the MAC does not match. It means that the message
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has been tampered with or that the MAC key is incorrect.
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"""
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self.verify(unhexlify(tobytes(hex_mac_tag)))
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def new(self, **kwargs):
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"""Return a new instance of a BLAKE2b hash object.
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See :func:`new`.
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"""
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if "digest_bytes" not in kwargs and "digest_bits" not in kwargs:
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kwargs["digest_bytes"] = self.digest_size
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return new(**kwargs)
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def new(**kwargs):
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"""Create a new hash object.
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Args:
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data (bytes/bytearray/memoryview):
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Optional. The very first chunk of the message to hash.
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It is equivalent to an early call to :meth:`BLAKE2b_Hash.update`.
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digest_bytes (integer):
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Optional. The size of the digest, in bytes (1 to 64). Default is 64.
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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 (8 to 512, in steps of 8).
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Default is 512.
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key (bytes/bytearray/memoryview):
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Optional. The key to use to compute the MAC (1 to 64 bytes).
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If not specified, no key will be used.
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update_after_digest (boolean):
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Optional. By default, a hash object cannot be updated anymore after
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the digest is computed. When this flag is ``True``, such check
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is no longer enforced.
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Returns:
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A :class:`BLAKE2b_Hash` hash object
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"""
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data = kwargs.pop("data", None)
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update_after_digest = kwargs.pop("update_after_digest", False)
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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 not (1 <= digest_bytes <= 64):
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raise ValueError("'digest_bytes' not in range 1..64")
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else:
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if not (8 <= digest_bits <= 512) or (digest_bits % 8):
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raise ValueError("'digest_bits' not in range 8..512, "
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"with steps of 8")
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digest_bytes = digest_bits // 8
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key = kwargs.pop("key", b"")
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if len(key) > 64:
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raise ValueError("BLAKE2b key cannot exceed 64 bytes")
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if kwargs:
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raise TypeError("Unknown parameters: " + str(kwargs))
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return BLAKE2b_Hash(data, key, digest_bytes, update_after_digest)
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