Analysis of DES Double Key Mode

Abstract

In this paper we examine closely a new mode of the Data Encryption Standard (DES), which is included in a new chip called SuperCrypt. This mode allows for a 112-bit key which encrypts at the same speed as DES. Initially, we give some background on the development of the cipher, and then proceed to cryptanalyse it using differential cryptanalysis and a combination of linear and differential cryptanal-ysis. We present results for the four, six and eight-round versions and comparisons with the DES. We theoretically extend this to the full sixteen-round version. Finally, we look at exhaustive key search in light of the fact that it has been proven feasible to construct a machine at realistic cost to find the DES key in a matter of hours.