Primality test

algorithm for determining whether an input number is prime

A primality test is a method (or algorithm) to find out if a certain number is a prime number. Cryptography uses prime numbers, and needs to test if a certain number is prime. The official proof of a prime is through its primality certificate.

Simple methods change

  • Sieve of Eratosthenes: Determine if there is a number (between 2 and n, the number to test) that divides n, without a rest
  • Wilson's theorem (inefficient):   evaluates to -1 mod p where p is the candidate prime number

Better methods change