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- - **Factoring large N into prime factors**
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factoring large N into prime factorsHi, I am writing up a project based on an algorithm for factoring large numbers, I have reached seemingly simple point where I am stuck, I wonder if anyone can help me?
I am trying to factor a large N such that N=pq for unknown primes p and q, I have described a method to find a value for (p-1)(q-1) from N and now have the problem of recovering p and q. So N is given and (p-1)(q-1) is given, how do I carry on? Thanks |

Re: factoring large N into prime factorsHi, Bert,
see this thread: http://www.physicsforums.com/showthread.php?t=584239 It would be interesting if you can comment on your method, as finding phi(n) for large semiprimes is hard. |

Re: factoring large N into prime factorsthanks, that's perfect.
The way in which i found (p-1)(q-1) is to take a set of sequences of powers of x mod N for x=1,2,...,N-1 and work out their periods, each period turns out to be a divisor of (p-1)(q-1), if a large enough number of divisors is taken, then the value of (p-1)(q-1) can be predicted with high probability. That's basically all I've got, if anyone knows the specific theorem I am exploiting here it would be greatly appreciated as I should include it in my work, I know it's Euler but I'm having trouble finding a specific name so I can reference it and perhaps find a proof. |

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