How to make DES-based Smartcards fit for the 21-st century: Cryptographic Techniques for Advanced Security Requirements
Stefan Lucks, Rüdiger Weis · 2001
With its 56-bit key size, the data encryption standard (DES) seems to be at end of its useful lifetime. Also, the 64-bit DES block size is dangerously small for some applications. We discuss techniques such as triple DES and DESX to push up the key size, and we present DEAL to increase both block and key size. We propose DEALkx, a new variant of DEAL with an improved key schedule.