Specifies methods for generating and testing prime numbers as required in cryptographic protocols and algorithms. Firstly, this International Standard specifies methods for testing whether a given number is prime. The testing methods included in this International Standard can be divided into two groups: &8226; Probabilistic primality tests, which have a small error probability. All probabilistic tests described here may declare a composite to be a prime. One test described here may declare a prime to be composite. &8226; Deterministic methods, which are guaranteed to give the right verdict. These methods use so-called primality certi.