Cache timing attacks on Clefia

Abstract

The paper discusses the performance of cache timing attacks on Clefia, which is based on the generalized Feistel structure and implemented using small tables. We mention the difficulties on mounting a timing based cache attack on the cipher, and then explain why a cache attack is still possible. To the best of our knowledge, no reported work on cache attacks target ciphers which are implemented with small tables. Our attack uses the fact that parallelization and pipelining of memory accesses can only be done within a single round of a cipher, but not across rounds. Our findings show that 121 bits of the 128 bit key can be revealed in 226.64 Clefia encryptions on an Intel Core 2 Duo machine. © 2009 Springer-Verlag.