I made a mistake with my description of finding the decryption key. You
actually need to find loop exponents for both the cipher text and a
reencryption of it (the second search is scaled to be faster and sometimes
the first exponent works for both). This is to make sure that the exponent
picked is of a period which fits the orbits both numbers lie on.

Once that exponent is found, it can be used in a manner similar to the
totient and the decryption exponent will be the modular multiplicative
inverse of the encryption exponent in that space.

Which is nifty.

I've coded up a proof of concept showing an actual attack on RSA type keys
and decrypting data given a semiprime and encryption exponent.

This approach appears to be novel and investigation to date leads me to
conclude that some real world keys might be vulnerable to it. Though the
proof of the pudding is in the eating so I'm looking for a way to test this
on a computer fast enough to do something interesting (let me know if you
have any thoughts on this).

I hope this helps.

Gabriel

Reply via email to