**Cube Test Analysis of the Statistical Behavior of CubeHash and Skein**

*Alan Kaminsky*

**Abstract: **This work analyzes the statistical properties of the SHA-3 candidate cryptographic hash algorithms CubeHash and Skein to try to find nonrandom behavior. Cube tests were used to probe each algorithm's internal polynomial structure for a large number of choices of the polynomial input variables. The cube test data were calculated on a 40-core hybrid SMP cluster parallel computer. The cube test data were subjected to three statistical tests: balance, independence, and off-by-one. Although isolated statistical test failures were observed, the balance and off-by-one tests did not find nonrandom behavior overall in either CubeHash or Skein. However, the independence test did find nonrandom behavior overall in both CubeHash and Skein.

**Category / Keywords: **implementation / one-way hash functions, statistical tests, cube tests, SHA-3, CubeHash, Skein

**Date: **received 7 May 2010

**Contact author: **ark at cs rit edu

**Available format(s): **Postscript (PS) | Compressed Postscript (PS.GZ) | PDF | BibTeX Citation

**Version: **20100507:232820 (All versions of this report)

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