The Secret-Key Block Cipher MKC1.

This paper proposes a new secret-key block cipher algorithm called MKC1. MKC1 is a Feistel-type block cipher with variable block length, key length, and number of rounds. The merits of this algorithm are that numerous structures can be formed by selecting the encryption functions and that cellular automata, which can ensure an immense number of structures, and power functions over a finite field, which have strong resistance to differential and linear attacks, are used for the encryption functions. These features increase MKC1's resistance to exhaustive key searches and analytical cryptanalysis. In addition, rules that are relatively powerful as encryption functions among the total of 256 rules for one-dimensional, two-state, neighborhood-three cellular automata were found to practically correspond to Class 3 of Wolfram's classification scheme. The results of computer experiments indicate that MKC1 is several times faster than DES. The industrial value of this algorithm was confirmed, by implementing it in an automatic electronic ticket system using a contactless IC card. [ABSTRACT FROM AUTHOR]