‘The CS^2 Block Cipher’


This paper describes a new CS block cipher that is an extension of the original CS-Cipher. The new design inherits the efficiency of the original design while being upgraded to support a larger block size as well as use a slightly improved substitution box.’


‘The original article can be found at: http://www.securescience.net/ciphers/csc2/


The CS-Cipher is a 64-bit block cipher designed for efficiency on 8-bit processors as well as in hardware. In their design they introduced the use of multi permutations as a design construct as well as a very non-linear round transform. In a subsequent paper, Vaudenay claimed that the active substitution box “sbox” count is at least 72 over the full cipher, thus concluding the design is immune to differential and linear cryptanalysis. As of yet no full cryptanalysis of the CS-Cipher is known to exist.

In this paper the CS-Cipher is extended using the results of [5] and [7] to produce an efficient 128-bit block cipher with a 128-bit secret key. It is shown how the design can be implemented efficiently as well as explain the hardware rationale. The white paper linked here also prove that the new design is immune to both differential and linear cryptanalysis. It is further argued that the new CS-Cipher design resists several other known attacks.

The full paper can be found at: http://www.securescience.net/ciphers/csc2/
Sample reference code can be found at: csc2ref.c

Categories: Reviews