Advanced Time-Driven Cache Attacks on Block Ciphers

In Chap. 4 we saw how an adversary can use the execution time of the Advanced Encryption Standard (AES) block cipher to obtain information about the secret key. The number of key bits that the adversary determines is however restricted by the size of the cache line. If a cache line holds \(2^\delta\) elements of a look-up table used in AES, then at least δ bits of the key are hidden from the adversary. In this chapter, we discuss how properties of the block cipher along with timing side channels can be used to determine more key bits. The chapter begins with a second round time-driven cache attack on AES and then dwells into differential cache attacks on Feistel ciphers.