# ===================================================================
#
# Copyright (c) 2015, Legrandin <[email protected]>
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# modification, are permitted provided that the following conditions
# are met:
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# 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
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# ===================================================================
from Cryptodome.Util.py3compat import bord
from Cryptodome.Util._raw_api import (load_pycryptodome_raw_lib,
VoidPointer, SmartPointer,
create_string_buffer,
get_raw_buffer, c_size_t,
c_uint8_ptr, c_ubyte)
from Cryptodome.Hash.keccak import _raw_keccak_lib
class SHAKE256_XOF(object):
"""A SHAKE256 hash object.
Do not instantiate directly.
Use the :func:`new` function.
:ivar oid: ASN.1 Object ID
:vartype oid: string
"""
# ASN.1 Object ID
oid = "2.16.840.1.101.3.4.2.12"
def __init__(self, data=None):
state = VoidPointer()
result = _raw_keccak_lib.keccak_init(state.address_of(),
c_size_t(64),
c_ubyte(24))
if result:
raise ValueError("Error %d while instantiating SHAKE256"
% result)
self._state = SmartPointer(state.get(),
_raw_keccak_lib.keccak_destroy)
self._is_squeezing = False
self._padding = 0x1F
if data:
self.update(data)
def update(self, data):
"""Continue hashing of a message by consuming the next chunk of data.
Args:
data (byte string/byte array/memoryview): The next chunk of the message being hashed.
"""
if self._is_squeezing:
raise TypeError("You cannot call 'update' after the first 'read'")
result = _raw_keccak_lib.keccak_absorb(self._state.get(),
c_uint8_ptr(data),
c_size_t(len(data)))
if result:
raise ValueError("Error %d while updating SHAKE256 state"
% result)
return self
def read(self, length):
"""
Compute the next piece of XOF output.
.. note::
You cannot use :meth:`update` anymore after the first call to
:meth:`read`.
Args:
length (integer): the amount of bytes this method must return
:return: the next piece of XOF output (of the given length)
:rtype: byte string
"""
self._is_squeezing = True
bfr = create_string_buffer(length)
result = _raw_keccak_lib.keccak_squeeze(self._state.get(),
bfr,
c_size_t(length),
c_ubyte(self._padding))
if result:
raise ValueError("Error %d while extracting from SHAKE256"
% result)
return get_raw_buffer(bfr)
def new(self, data=None):
return type(self)(data=data)
def new(data=None):
"""Return a fresh instance of a SHAKE256 object.
Args:
data (bytes/bytearray/memoryview):
The very first chunk of the message to hash.
It is equivalent to an early call to :meth:`update`.
Optional.
:Return: A :class:`SHAKE256_XOF` object
"""
return SHAKE256_XOF(data=data)