118 lines
3.6 KiB
Python
118 lines
3.6 KiB
Python
# Copyright (c) 2017 PySecretHandshake contributors (see AUTHORS for more details)
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#
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# Permission is hereby granted, free of charge, to any person obtaining a copy
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# of this software and associated documentation files (the "Software"), to deal
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# in the Software without restriction, including without limitation the rights
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# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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# copies of the Software, and to permit persons to whom the Software is
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# furnished to do so, subject to the following conditions:
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#
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# The above copyright notice and this permission notice shall be included in all
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# copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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# SOFTWARE.
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import struct
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from io import BytesIO
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NONCE_SIZE = 24
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MAX_NONCE = (8 * NONCE_SIZE)
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class AsyncBuffer(BytesIO):
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"""Just a BytesIO with an async read method."""
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async def read(self, n=None):
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v = super(AsyncBuffer, self).read(n)
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return v
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readexactly = read
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def append(self, data):
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"""Append data to the buffer without changing the current position."""
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pos = self.tell()
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self.write(data)
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self.seek(pos)
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async def async_comprehend(generator):
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"""Emulate ``[elem async for elem in generator]``."""
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results = []
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async for msg in generator:
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results.append(msg)
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return results
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def inc_nonce(nonce):
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num = bytes_to_long(nonce) + 1
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if num > 2 ** MAX_NONCE:
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num = 0
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bnum = long_to_bytes(num)
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bnum = b'\x00' * (NONCE_SIZE - len(bnum)) + bnum
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return bnum
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def split_chunks(seq, n):
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"""Split sequence in equal-sized chunks.
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The last chunk is not padded."""
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while seq:
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yield seq[:n]
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seq = seq[n:]
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# Stolen from PyCypto (Public Domain)
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def b(s):
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return s.encode("latin-1") # utf-8 would cause some side-effects we don't want
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def long_to_bytes(n, blocksize=0):
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"""long_to_bytes(n:long, blocksize:int) : string
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Convert a long integer to a byte string.
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If optional blocksize is given and greater than zero, pad the front of the
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byte string with binary zeros so that the length is a multiple of
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blocksize.
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"""
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# after much testing, this algorithm was deemed to be the fastest
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s = b('')
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pack = struct.pack
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while n > 0:
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s = pack('>I', n & 0xffffffff) + s
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n = n >> 32
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# strip off leading zeros
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for i in range(len(s)):
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if s[i] != b('\000')[0]:
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break
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else:
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# only happens when n == 0
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s = b('\000')
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i = 0
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s = s[i:]
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# add back some pad bytes. this could be done more efficiently w.r.t. the
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# de-padding being done above, but sigh...
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if blocksize > 0 and len(s) % blocksize:
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s = (blocksize - len(s) % blocksize) * b('\000') + s
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return s
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def bytes_to_long(s):
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"""bytes_to_long(string) : long
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Convert a byte string to a long integer.
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This is (essentially) the inverse of long_to_bytes().
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"""
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acc = 0
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unpack = struct.unpack
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length = len(s)
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if length % 4:
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extra = (4 - length % 4)
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s = b('\000') * extra + s
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length = length + extra
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for i in range(0, length, 4):
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acc = (acc << 32) + unpack('>I', s[i:i+4])[0]
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return acc
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