Square reflection cryptanalysis of 5-round Feistel networks with permutations
New distinguishers are derived for 4-round Feistel Networks with permutational round functions under a weak key condition. A new generic attack is mounted on 5-round Feistel Networks by combining the square attack and the reflection attack. Hellman tables are utilized to construct a tradeoff between the time complexity and the memory complexity of the new attack. The generic attack is applied to 5-round DEAL as a concrete example. The complexity of the attack on DEAL is 265 DES encryptions, working on a key set of cardinality 272.
feistel network square attack reflection attack deal cryptography block cipher fixed point