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Fix RSA LSBit Oracle attack to not mess up last bytes #9
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The previous approach of updating the upper/lower limits to be the mid-point between them would truncate the result multiple times along the way, leading to an incorrect last byte at the end. By keeping track of numerators/denominators separately, we can get an accurate decryption. Learned about this approach from: https://github.com/akalin/cryptopals-python3/blob/master/challenge46.py
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The previous approach of updating the upper/lower limits to be the
mid-point between them would truncate the result multiple times along
the way, leading to an incorrect last byte at the end. By keeping track
of numerators/denominators separately, we can get an accurate
decryption.
Learned about this approach from:
https://github.com/akalin/cryptopals-python3/blob/master/challenge46.py
Tested with
exploit.py, where I am now able to recover a full flag, instead of getting incorrect last bytes.Also tested
lsbitoracle.pyby creating a small script that calls it, where it also recovers the full flag now.