206 lines
6.7 KiB
Python
206 lines
6.7 KiB
Python
# /usr/bin/env python
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# coding=utf-8
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# Copyright 2010 Jonathan Bowman
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
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# implied. See the License for the specific language governing
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# permissions and limitations under the License.
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"""Pure Python implementation of the Skein 512-bit hashing algorithm"""
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import array
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import binascii
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import os
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import struct
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from threefish import (add64, bigint, bytes2words, Threefish512, words,
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words2bytes, words_format, xrange,
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zero_bytes, zero_words)
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# An empty bytestring that behaves itself whether in Python 2 or 3
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empty_bytes = array.array('B').tostring()
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class Skein512(object):
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"""Skein 512-bit hashing algorithm
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The message to be hashed may be set as `msg` when initialized, or
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passed in later using the ``update`` method.
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Use `key` (a bytestring with arbitrary length) for MAC
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functionality.
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`block_type` will typically be "msg", but may also be one of:
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"key", "nonce", "cfg_final", or "out_final". These will affect the
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tweak value passed to the underlying Threefish block cipher. Again,
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if you don't know which one to choose, "msg" is probably what you
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want.
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Example:
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>>> Skein512("Hello, world!").hexdigest()
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'8449f597f1764274f8bf4a03ead22e0404ea2dc63c8737629e6e282303aebfd5dd96f07e21ae2e7a8b2bdfadd445bd1d71dfdd9745c95b0eb05dc01f289ad765'
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"""
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block_size = 64
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block_bits = 512
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block_type = {'key': 0,
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'nonce': 0x5400000000000000,
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'msg': 0x7000000000000000,
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'cfg_final': 0xc400000000000000,
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'out_final': 0xff00000000000000}
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def __init__(self, msg='', digest_bits=512, key=None,
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block_type='msg'):
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self.tf = Threefish512()
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if key:
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self.digest_bits = 512
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self._start_new_type('key')
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self.update(key)
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self.tf.key = bytes2words(self.final(False))
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self.digest_bits = digest_bits
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self.digest_size = (digest_bits + 7) >> 3
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self._start_new_type('cfg_final')
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b = words2bytes((0x133414853,digest_bits,0,0,0,0,0,0))
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self._process_block(b,32)
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self._start_new_type(block_type)
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if msg:
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self.update(msg)
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def _start_new_type(self, block_type):
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"""Setup new tweak values and internal buffer.
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Primarily for internal use.
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"""
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self.buf = empty_bytes
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self.tf.tweak = words([0, self.block_type[block_type]])
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def _process_block(self, block, byte_count_add):
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"""Encrypt internal state using Threefish.
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Primarily for internal use.
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"""
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block_len = len(block)
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for i in xrange(0,block_len,64):
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w = bytes2words(block[i:i+64])
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self.tf.tweak[0] = add64(self.tf.tweak[0], byte_count_add)
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self.tf.prepare_tweak()
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self.tf.prepare_key()
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self.tf.key = self.tf.encrypt_block(w)
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self.tf._feed_forward(self.tf.key, w)
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# set second tweak value to ~SKEIN_T1_FLAG_FIRST:
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self.tf.tweak[1] &= bigint(0xbfffffffffffffff)
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def update(self, msg):
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"""Update internal state with new data to be hashed.
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`msg` is a bytestring, and should be a bytes object in Python 3
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and up, or simply a string in Python 2.5 and 2.6.
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"""
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self.buf += msg
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buflen = len(self.buf)
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if buflen > 64:
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end = -(buflen % 64) or (buflen-64)
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data = self.buf[0:end]
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self.buf = self.buf[end:]
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try:
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self._process_block(data, 64)
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except:
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print(len(data))
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print(binascii.b2a_hex(data))
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def final(self, output=True):
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"""Return hashed data as bytestring.
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`output` is primarily for internal use. It should only be False
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if you have a clear reason for doing so.
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This function can be called as either ``final`` or ``digest``.
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"""
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self.tf.tweak[1] |= bigint(0x8000000000000000) # SKEIN_T1_FLAG_FINAL
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buflen = len(self.buf)
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self.buf += zero_bytes[:64-buflen]
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self._process_block(self.buf, buflen)
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if not output:
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hash_val = words2bytes(self.tf.key)
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else:
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hash_val = empty_bytes
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self.buf = zero_bytes[:]
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key = self.tf.key[:] # temporary copy
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i=0
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while i*64 < self.digest_size:
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self.buf = words_format[1].pack(i) + self.buf[8:]
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self.tf.tweak = [0, self.block_type['out_final']]
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self._process_block(self.buf, 8)
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n = self.digest_size - i*64
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if n >= 64:
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n = 64
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hash_val += words2bytes(self.tf.key)[0:n]
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self.tf.key = key
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i+=1
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return hash_val
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digest = final
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def hexdigest(self):
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"""Return a hexadecimal representation of the hashed data"""
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return binascii.b2a_hex(self.digest())
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class Skein512Random(Skein512):
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"""A Skein-based pseudo-random bytestring generator.
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If `seed` is unspecified, ``os.urandom`` will be used to provide the
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seed.
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In case you are using this as an iterator, rather than generating
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new data at each iteration, a pool of length `queue_size` is
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generated periodically.
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"""
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def __init__(self, seed=None, queue_size=512):
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Skein512.__init__(self, block_type='nonce')
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self.queue = []
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self.queue_size = queue_size
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self.tf.key = zero_words[:]
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if not seed:
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seed = os.urandom(100)
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self.reseed(seed)
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def reseed(self, seed):
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"""(Re)seed the generator."""
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self.digest_size = 64
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self.update(words2bytes(self.tf.key) + seed)
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self.tf.key = bytes2words(self.final())
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def getbytes(self, request_bytes):
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"""Return random bytestring of length `request_bytes`."""
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self.digest_size = 64 + request_bytes
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self.update(words2bytes(self.tf.key))
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output = self.final()
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self.tf.key = bytes2words(output[0:64])
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return output[64:]
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def __iter__(self):
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return self
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def next(self):
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if not self.queue:
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self.queue = array.array('B', self.getbytes(self.queue_size))
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return self.queue.pop()
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if __name__ == '__main__':
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print Skein512('123').hexdigest() |