274 lines
9.9 KiB
Python
274 lines
9.9 KiB
Python
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# ===================================================================
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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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"""BLAKE2s cryptographic hash algorithm.
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`BLAKE2s`_ is an optimized variant of BLAKE, one of the SHA-3 candidates that
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made it to the final round of the NIST hash competition.
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The algorithm uses 32 bit words, and it therefore works best
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on 32-bit platforms. The digest size ranges from 8 to 256 bits.
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>>> from Crypto.Hash import BLAKE2s
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>>>
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>>> h_obj = BLAKE2s.new(digest_bits=256)
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>>> h_obj.update(b'Some data')
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>>> print h_obj.hexdigest()
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Optionally, BLAKE2s can work as a cryptographic MAC when initialized
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with a secret key.
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>>> from Crypto.Hash import BLAKE2s
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>>>
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>>> mac = BLAKE2s.new(digest_bits=128, key=b'secret')
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>>> mac.update(b'Some data')
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>>> print mac.hexdigest()
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:undocumented: __package__
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.. _BLAKE2s: https://blake2.net/
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"""
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from binascii import unhexlify
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from Crypto.Util.py3compat import b, bord, tobytes
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from Crypto.Random import get_random_bytes
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from Crypto.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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expect_byte_string)
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_raw_blake2s_lib = load_pycryptodome_raw_lib("Crypto.Hash._BLAKE2s",
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"""
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int blake2s_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 blake2s_destroy(void *state);
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int blake2s_update(void *state,
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const uint8_t *buf,
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size_t len);
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int blake2s_digest(const void *state,
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uint8_t digest[32]);
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int blake2s_copy(const void *src, void *dst);
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""")
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class BLAKE2s_Hash(object):
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"""Class that implements a BLAKE2s hash
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"""
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#: The internal block size of the hash algorithm in bytes.
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block_size = 32
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def __init__(self, data, key, digest_bytes, update_after_digest):
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"""
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Initialize a BLAKE2s hash object.
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"""
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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/draft-saarinen-blake2-02
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if digest_bytes in (16, 20, 28, 32) and not key:
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self.oid = "1.3.6.1.4.1.1722.12.2.2." + str(digest_bytes)
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expect_byte_string(key)
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state = VoidPointer()
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result = _raw_blake2s_lib.blake2s_init(state.address_of(),
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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 BLAKE2s" % result)
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self._state = SmartPointer(state.get(),
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_raw_blake2s_lib.blake2s_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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Repeated calls are equivalent to a single call with the concatenation
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of all the arguments. In other words:
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>>> m.update(a); m.update(b)
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is equivalent to:
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>>> m.update(a+b)
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:Parameters:
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data : byte string
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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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expect_byte_string(data)
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result = _raw_blake2s_lib.blake2s_update(self._state.get(),
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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 BLAKE2s 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
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has been hashed so far.
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You cannot update the hash anymore after the first call to ``digest``
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(or ``hexdigest``).
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:Return: A byte string of `digest_size` bytes. It may contain non-ASCII
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characters, including null bytes.
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"""
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bfr = create_string_buffer(32)
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result = _raw_blake2s_lib.blake2s_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 BLAKE2s 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
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so far.
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This method does not change the state of the hash object.
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:Return: A string of 2* `digest_size` characters. It contains only
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hexadecimal ASCII digits.
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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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:Parameters:
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mac_tag : byte string
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The expected MAC of the message.
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:Raises ValueError:
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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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:Parameters:
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hex_mac_tag : string
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The expected MAC of the message, as a hexadecimal string.
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:Raises ValueError:
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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 BLAKE2s hash object."""
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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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"""Return a new instance of a BLAKE2s hash object.
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:Keywords:
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data : byte string
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The very first chunk of the message to hash.
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It is equivalent to an early call to `BLAKE2s_Hash.update()`.
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digest_bytes : integer
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The size of the digest, in bytes (1 to 32).
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digest_bits : integer
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The size of the digest, in bits (8 to 256, in steps of 8).
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key : byte string
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The key to use to compute the MAC (1 to 32 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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:Return: A `BLAKE2s_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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raise TypeError("Digest size (bits, bytes) not provided")
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if digest_bytes is not None:
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if not (1 <= digest_bytes <= 32):
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raise ValueError("'digest_bytes' not in range 1..32")
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else:
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if not (8 <= digest_bits <= 256) or (digest_bits % 8):
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raise ValueError("'digest_bytes' not in range 8..256, "
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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) > 32:
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raise ValueError("BLAKE2s key cannot exceed 32 bytes")
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if kwargs:
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raise TypeError("Unknown parameters: " + str(kwargs))
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return BLAKE2s_Hash(data, key, digest_bytes, update_after_digest)
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