Statistical weakness in Spritz against VMPC-R: in search for the RC4 replacement

Bartosz Zoltak

Paper 2014/985

Statistical weakness in Spritz against VMPC-R: in search for the RC4 replacement

Bartosz Zoltak

Abstract

We found a statistical weakness in the Spritz algorithm designed by Ronald L. Rivest and Jacob C. N. Schuldt. For N=8: Prob(output(x)=output(x+2)) = 1/N + 0.000498. The bias becomes statistically significant (for N=8) after observing about 2^21.9 outputs. Analogous bias occurs for N=16. We propose an algorithm (VMPC-R) which for N=8 produced 2^46.8 (31 million times more) outputs which remained undistinguishable from random in the same battery of tests. Supported by a series of additional statistical tests and security analyses we present VMPC-R as an algorithm we hope can be considered a worthwhile replacement for RC4.

Metadata

Available format(s): PDF
Category: Secret-key cryptography
Publication info: Preprint. MINOR revision.
Keywords: PRNG CSPRNG Spritz RC4 VMPC-R stream cipher distinguishing attack
Contact author(s): bzoltak @ vmpcfunction com
History: 2014-12-10: received
Short URL: https://ia.cr/2014/985
License: CC BY

BibTeX

@misc{cryptoeprint:2014/985,
      author = {Bartosz Zoltak},
      title = {Statistical weakness in Spritz against {VMPC}-R: in search for the {RC4} replacement},
      howpublished = {Cryptology {ePrint} Archive, Paper 2014/985},
      year = {2014},
      url = {https://eprint.iacr.org/2014/985}
}