Deterministic factoring with oracles

02/23/2018

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by   François Morain, et al.

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We revisit the problem of integer factorization with number-theoretic oracles, including a well-known problem: can we factor an integer N unconditionally, in deterministic polynomial time, given the value of the Euler totient (φ(N)? We show that this can be done, under certain size conditions on the prime factors of N. The key technique is lattice basis reduction using the LLL algorithm. Among our results, we show for example that if N is a squarefree integer with a prime factor p > √(N) , then we can recover p in deterministic polynomial time given φ(N)). We also shed some light on the analogous problems for Carmichael's function, and the order oracle that is used in Shor's quantum factoring algorithm.