RSA multi factor
 

hi,
i have used the YaFu and entered a N of an RSA and it solved it by giving me back 15 primes... how can i continue from this point on to break the small RSA key that i have ?

Are you sure you've got the right N? Any good key choice (if not [I]any[/I] valid key, if [URL="https://en.wikipedia.org/wiki/RSA_problem"]this article's[/URL] offhand comment is right) will be a semiprime, not consist of 15 primes.

Anyway, once you've got the right number factored, [URL="http://stackoverflow.com/questions/4078902/cracking-short-rsa-keys"]this post from StackOverflow[/URL] goes into (the mathematical side, not a script or anything) how to calculate the private key. The most important part is this: (d is the private exponent, e is the public exponent, n is the public key, n is semiprime with factors p and q)

[CODE]d = e^-1 mod phi(n)
= e^-1 mod (p-1)*(q-1)[/CODE]
(note that if you don't have a semiprime, the [URL="https://en.wikipedia.org/wiki/Euler's_totient_function"]phi calculation[/URL] gets more complicated)

Then you just need to compute that [URL="https://en.wikipedia.org/wiki/Modular_multiplicative_inverse"]modular multiplicative inverse[/URL], convert the number into a usable format (hex?) and use it. :smile:

Sounds like a Teslacrypt infection. You may wish to head over here if that's the case: [url]http://www.mersenneforum.org/showthread.php?t=20767[/url]