71 lines
2.1 KiB
Python
71 lines
2.1 KiB
Python
#!/usr/bin/env python
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from hashlib import sha3_256
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from itertools import count, islice
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from Crypto.Cipher import ChaCha20
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from math import floor, ceil
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from time import sleep
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from os import environ
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from sys import stderr
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def debug(*args):
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if 'DEBUG' in environ:
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print(*args, file=stderr)
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def chacha_bits(input, bit_count):
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zerobyte = (0).to_bytes(length=1, byteorder='big')
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cipher = ChaCha20.new(key=sha3_256(input).digest(), nonce=zerobyte*8)
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i = 0
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while True:
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debug(f'--- BITS {i} ---')
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start_bit = bit_count * i
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start_byte = start_bit // 8
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start_padding = start_bit % 8
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debug('start_bit', start_bit)
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debug('start_byte', start_byte)
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debug('start_padding', start_padding)
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end_bit = bit_count * i + bit_count
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end_byte = end_bit // 8
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end_padding = 8 - (end_bit % 8)
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debug('end_bit', end_bit)
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debug('end_byte', end_byte)
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debug('end_padding', end_padding)
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byte_count = (end_byte - start_byte) + 1
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debug('byte_count', byte_count)
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cipher.seek(start_byte)
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cipherint = int.from_bytes(cipher.encrypt(zerobyte*byte_count), byteorder='big')
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debug('ciphertext', bin(cipherint))
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shifted_cipherint = cipherint >> end_padding
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debug('shifted_ciphertext', bin(shifted_cipherint))
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bit_mask = int('1'*bit_count, 2)
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debug('bit_mask', bin(bit_mask))
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masked_cipherint = shifted_cipherint & bit_mask
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debug('masked_ciphertext', bin(masked_cipherint))
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debug('')
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yield masked_cipherint
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i += 1
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def chacha_chracter(input, choices):
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get_bits = chacha_bits(input, len(choices).bit_length())
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while True:
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key = next(get_bits)
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if key < len(choices):
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yield choices[key]
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def derive_string(input, length, choices):
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sorted_choices = bytes(sorted(choices))
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get_character = chacha_chracter(input, sorted_choices)
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return bytes(islice(get_character, length))
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# print(
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# derive_string(b'12344', length=100, choices=b'abcdefghijklmnopqrstuvwxyz0123456789')
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# )
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