Random and pseudorandom bit generators (RBGs, PRBGs) are used for many purposes including cryptographic, modeling, and simulation applications. For cryptographic purpose, they are required in the construction of encryption keys, other cryptographic parameters, and so on. One of the criteria used to evaluate the Advanced Encryption Standard (AES) candidate algorithms was their demonstrated suitability as PRBGs. That is, the evaluation of their outputs utilizing statistical tests should not provide any means by which to computationally distinguish them from truly random sources.