On the security of the 128-bit block cipher DEAL

Abstract

DEAL is a DES-based block cipher proposed by Knudsen. The block size of DEAL is 128 bits, twice as much as the DES block size. The main result of the current paper is a certificational attack on DEAL- 192, the DEAL variant with a 192-bit key. The attack allows a trade-off between the number of plaintext/ciphertext pairs and the time for the attacker’s computations. Nevertheless, the DEAL design principle seems to be a useful way of doubling the block size of a given block cipher.