  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.

Cryptography and Security