Stream cipher was widely used and the random number tests of the key stream play a key role in information security. Unlike usual NIST random number test for the random sequence with selected length, this article was focused on splitting the random sequence to do the NIST random number test. Then, the frequency distribution was measured through using the test results. Finally, two-dimensional feature map was generated. The selected test data show that such feature maps distinguish the key streams generated by HC256 and RC4 through the feature maps explicitly.
Andrew Rukhin, Juan Soto, James Nechvatal, Miles Smid, Elaine Barker, Stefan Leigh, Mark Levenson, Mark Vangel, David Banks, Alan Heckert, James Dray, San Vo (2010) A statistical test suite for random and pseudorandom number generators for cryptographic applications. NIST Special Publication 800-22 Revision 1a.