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+# ===================================================================
+#
+# Copyright (c) 2015, Legrandin <helderijs@gmail.com>
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 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
+# notice, this list of conditions and the following disclaimer in
+# the documentation and/or other materials provided with the
+# distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+# ===================================================================
+
+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)
+
+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),
+ 0x1F)
+ if result:
+ raise ValueError("Error %d while instantiating SHAKE256"
+ % result)
+ self._state = SmartPointer(state.get(),
+ _raw_keccak_lib.keccak_destroy)
+ self._is_squeezing = False
+ 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))
+ 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)