| Thus, Fermat's theorem gives a test that is necessary but not sufficient for primality. |
| However, if Dr Agrawal's primality test can be extended to factoring numbers, it would mean a rejigging of modern cryptography. |
| So-called primality testing plays a crucial role in the widely used RSA algorithm, whose security relies on the difficulty of finding a number's prime factors. |
| There is a new appendix on the recently discovered unconditional deterministic polynomial-time algorithm for primality testing. |
| Instead, mathematicians turn to other, indirect, methods that can test for primality without factorisation. |
| These are unary addition, problem of divisibility and the problem of primality. |
