Create keccak.py
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Evan Su
GitHub
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# ===================================================================
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#
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# Copyright (c) 2015, 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 Crypto.Util.py3compat import bord
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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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c_uint8_ptr)
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_raw_keccak_lib = load_pycryptodome_raw_lib("Crypto.Hash._keccak",
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"""
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int keccak_init(void **state,
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size_t capacity_bytes,
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uint8_t padding_byte);
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int keccak_destroy(void *state);
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int keccak_absorb(void *state,
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const uint8_t *in,
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size_t len);
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int keccak_squeeze(const void *state,
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uint8_t *out,
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size_t len);
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int keccak_digest(void *state, uint8_t *digest, size_t len);
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int keccak_copy(const void *src, void *dst);
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""")
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class Keccak_Hash(object):
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"""A Keccak hash object.
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Do not instantiate directly.
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Use the :func:`new` function.
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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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def __init__(self, data, 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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state = VoidPointer()
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result = _raw_keccak_lib.keccak_init(state.address_of(),
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c_size_t(self.digest_size * 2),
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0x01)
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if result:
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raise ValueError("Error %d while instantiating keccak" % result)
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self._state = SmartPointer(state.get(),
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_raw_keccak_lib.keccak_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 (byte string/byte array/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_keccak_lib.keccak_absorb(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 updating keccak" % 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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self._digest_done = True
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bfr = create_string_buffer(self.digest_size)
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result = _raw_keccak_lib.keccak_digest(self._state.get(),
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bfr,
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c_size_t(self.digest_size))
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if result:
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raise ValueError("Error %d while squeezing keccak" % result)
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return get_raw_buffer(bfr)
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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 self.digest()])
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def new(self, **kwargs):
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"""Create a fresh Keccak 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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"""Create a new hash object.
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Args:
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data (bytes/bytearray/memoryview):
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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 :meth:`Keccak_Hash.update`.
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digest_bytes (integer):
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The size of the digest, in bytes (28, 32, 48, 64).
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digest_bits (integer):
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The size of the digest, in bits (224, 256, 384, 512).
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update_after_digest (boolean):
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Whether :meth:`Keccak.digest` can be followed by another
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:meth:`Keccak.update` (default: ``False``).
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:Return: A :class:`Keccak_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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raise TypeError("Digest size (bits, bytes) not provided")
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if digest_bytes is not None:
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if digest_bytes not in (28, 32, 48, 64):
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raise ValueError("'digest_bytes' must be: 28, 32, 48 or 64")
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else:
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if digest_bits not in (224, 256, 384, 512):
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raise ValueError("'digest_bytes' must be: 224, 256, 384 or 512")
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digest_bytes = digest_bits // 8
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if kwargs:
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raise TypeError("Unknown parameters: " + str(kwargs))
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return Keccak_Hash(data, digest_bytes, update_after_digest)
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