Created
July 6, 2019 16:36
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Tripwire style base64 encoding.
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#!/usr/bin/env python3 | |
# | |
# Tripwire style base64 encoding. | |
# It makes sense only for 4 byte aligned sequences and is slow. | |
# See: https://github.com/Tripwire/tripwire-open-source/blob/master/src/fco/signature.cpp#L201 | |
# | |
# Example usage for MD5 sum of files as appearing in tripwire reports: | |
# | |
# md5sum * | python twb64.py | |
# | |
from struct import unpack | |
from binascii import unhexlify | |
from functools import reduce | |
import sys | |
twb64chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" | |
def to_twb64(data): | |
bitseq_orig = reduce(lambda x,y: x+format(y, '032b'), unpack(f'!{int(len(data) / 4)}I', data), '') | |
offs = len(bitseq_orig) % 6 | |
head = [int(bitseq_orig[:offs], 2)] if offs > 0 else [] | |
tail_bits = bitseq_orig[offs:] | |
tail_6bit_list = [int(tail_bits[x:x+6],2) for x in range(0,len(tail_bits),6)] | |
return reduce(lambda x,y: x+y, [twb64chars[x] for x in head + tail_6bit_list], '') | |
if __name__ == '__main__': | |
for l in sys.stdin.read().splitlines(): | |
(h, f) = l.split() | |
print(to_twb64(unhexlify(h)), f) |
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