Skein (hash function)

Skein ( English for " strand " ) is a family of cryptographic hash functions and was developed by Niels Ferguson, Stefan Lucks, Bruce Schneier, Doug Whiting, Mihir Bellare, Tadayoshi Kohno, Jon Callas and Jesse Walker. Skein was a candidate in the competition for the future standard SHA -3, in which he reached the round of finalists in December 2010.


Skein uses a compression function based on block encryption Three Fish. The compression function consists of 72 rounds with a block size of 256 or 512 bits. With a block size of 1024 bits 80 rounds are used. Especially for Skein construction method was Unique Block Iteration ( UBI ) was developed, which replaces the previously used Merkle - Damgård construction. The design is optimized in order to achieve 64 -bit processors, a high performance. With a block size of 512 bits, the computational effort is on an Intel Core 2 Duo about 6 cycles per byte.


On the second SHA -3 Conference Dmitry Khovratovich, Ivica Nikolié and Christian Rechberger showed a potential weakness in Three Fish and the compression function of Skein. Then, the authors adjusted the algorithm slightly.