An Efficient Indexing Technique for AES Lookup Table to Prevent Side-Channel Cache Timing Attack

Abstract

In the era of virtualization, co-residency with unknown neighbours is a necessary evil and leakage of information through side-channels is an inevitable fact. Preventing this leakage of information through sidechannels, while maintaining high efficiency, has become one of the most challenging parts of any implementation of the Advanced Encryption Standard (AES) that is based on the Rijndael Cipher. Exploiting the associative nature of the cache and susceptible memory access pattern, AES is proved to be vulnerable to side-channel cache-timing attacks. The reason of this vulnerability is primarily ascribed to the existence of correlation between the index Bytes of the State matrix and corresponding accessed memory blocks. In this paper, we idealized the model of cache-timing attack and proposed a way of breaking this correlation through the implementation of a Random Address Translator (RAT). The simplicity of the design architecture of RAT can make itself a good choice as a way of indexing the lookup tables for the implementers of the AES seeking resistance against side-channel cachetiming attacks.