a normal gif file would start with #000000 and end with #FFFFFF, and then #000000 padding duplicates or alike in the colormap (e.g. There is not much possibilities for stegano in GIF as the image is made of refs to the colormap so it could be: We use LLL-based attack when more than quarter of the secret exponent bits are knownĪfter finding 300 least significant bits of p, we can use Coppersmith method for finding small roots of polynomials modulo pĮxtract gif file and get some info with `gifsicle -xinfo greg.gif`
ERASE TOOL IN PIXELSHOP FULL
Part2: faults only in the 300 least significant bits of dīut there is a theorem stating that we need only n/4 of the LSB bits to recover full d, as long as e is reasonably small If k'th bit in d was 0 and was flipped to 1, then d = d + 2^k so pow(m, d + 2^k) = pow(m, d) * pow(m, 2^k) (mod k) If k'th bit in d was 1 and was flipped to 0, then d = d - 2^k so pow(m, d - 2^k) = pow(m, d) / pow(m, 2^k) (mod k) We can test every k because there are only 1024 possible values Therefore we get badsig = m^(d (xor) 2^k) % N = m^(d - 2^k) % N So maybe the server sometimes flips one single bit of the secret exponent d We see that the different signatures match the size of the modulus in bits Fault attack on textbook RSA signing (not RSA-CRT)ĭecryption oracle sometimes give different signatures (m^d) for the same m
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