Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Randomness Testing of the Advanced Encryption Standard Finalist Candidates



Juan Soto, Lawrence E. Bassham


Mars, RC6, Rijndael, Serpent and Twofish were selected as finalists for the Advanced Encryption Standard (AES). To evaluate the finalists' suitability as random number generators, empirical statistical testing is commonly employed. Although it widely believed that these five algorithms are indeed random, randomness testing was conducted to show that there is empirical evidence supporting this belief. In this paper, NIST reports on the studies that were conducted on the finalists for the 192-bit key size and 256-bit key size. The results to date suggest that all five of the finalists appear to be random.
NIST Interagency/Internal Report (NISTIR) - 6483
Report Number


Advanced Encryption Standard (AES), random number generators, randomness, statistical tests


Soto, J. and Bassham, L. (2000), Randomness Testing of the Advanced Encryption Standard Finalist Candidates, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD, [online],, (Accessed April 15, 2024)
Created March 31, 2000, Updated October 12, 2021