Biblio

In this work, we examine the following question: How can we improve the best data complexity among the impossible differential (ID) attacks on AES? One of the most efficient attacks on AES are ID attacks. We have seen that the Biham-Keller ID characteristics are frequently used in these ID attacks. We observe the following fact: The probability that a given pair with a wrong key produce an ID characteristic is closely correlated to the data usage negatively. So, we maximize this probability by exploiting a Biham-Keller ID characteristic in a different manner than the other attacks. As a result, we mount an ID attack on 7-round AES-192 and obtain the best data requirement among all the ID attacks on 7-round AES. We make use of only 2$^\textrm58$ chosen plaintexts.