 It is currently recommended that "n" be at least 2048 bits long.In 1994, Peter Shor showed that a quantum computer – if one could ever be practically created for the purpose – would be able to factor in polynomial time, breaking RSA; see Shor's algorithm.Finding the large primes "p" and "q" is usually done by testing random numbers of the right size with probabilistic primality tests that quickly eliminate virtually all of the nonprimes.