Abstract
The paper analyzes cache based timing attacks on optimized codes for Advanced Encryption Standard (AES). The work justifies that timing based cache attacks create hits in the first and second rounds of AES, in a manner that the timing variations leak information of the key. To the best of our knowledge, the paper justifies for the first time that these attacks are unable to force hits in the third round and concludes that a similar third round cache timing attack does not work. The paper experimentally verifies that protecting only the first two AES rounds thwarts cache based timing attacks.