A Modular approach on Statistical Randomness Study of bit sequences

Randomness studies of bit sequences, created either by a ciphering algorithm or by a pseudorandom bit generator are a subject of prolonged research interest. During the recent past the 15 statistical tests of NIST turn out to be the most important as well as dependable tool for the same. For searching a right pseudorandom bit generator from among many such algorithms, large time is required to run the complete NIST statistical test suite. In this paper three test modules are considered in succession to reduce the searching time. The module-1 has one program and is executed almost instantly. The module-2 has four programs and takes about half an hour. The module-3 has fifteen programs and takes about four to five hours depending on the machine configuration. To choose the right pseudorandom bits generator, the algorithms rejected by the first module are not considered by the second module while the third module does consider only those passed by the second module.