Randomness of Spritz via DieHarder testing
This work addresses the security of network traffic encryption by evaluating a candidate cipher for TLS, but it is incremental as it applies standard testing to a new algorithm.
The researchers tested the randomness of the Spritz stream cipher, a potential replacement for RC4, using the DieHarder test suite on 1024 keystreams of 2^25 bits each, and found that no tests failed, with weak results corrected by increasing sample sizes.
RC4 is a stream cipher included in the TLS protocol, and widely used for encrypting network traffic during the last decades. Spritz is a possible candidate for replacing RC4. Spritz is based on a sponge construction and preserves the byte-oriented behaviour existing in RC4, but introduces an interface that provides encryption, hashing or MAC-generation functionalities. We present here the results obtained after applying several statistical tests on the keystreams generated by Spritz when used in the cipher mode. Our methodology makes use of 1024 keystreams of 2^25 bits. The algorithm was tested against the DieHarder test suite. None of the tests failed. Few tests produced weak results that were corrected when the number of samples increased.