SC2000

SC2000 is a algorithm of Chiffrement per block conceived by Cryptographe S Japanese of the laboratories of Fujitsu. Presented in 2000 to the project Nessie, it did not pass phase I (like six others algorithms).

SC2000 consists of a layer of 32 tables of substitution (or S-Box ) of 4 bits each one, then of two turns in a Réseau of Feistel. For each turn the keys are combined by XOR with the quantified storage block, before and after the treatment via the S-Box . The final half-stage includes/understands additions of key and research in the S-Box . The function F of the network of Feistel is a layer of four S-Boxes of 6 bits and eight S-Box of 5 bits, a multiplication by a matrix of 32x32 bits and combination by binary operations of the resulting words. Two words are obtained at exit of this function in the network of Feistel.

The Key schedule is a complex transformation of the key of the user, in the direction where each of the 32 bits of the intermediate keys depends on the whole of the key.

Cryptanalyse

In 2001, Raddum and Knudsen on the one hand and Dunkelman and Keller on the other hand brought back possibilities of attack by Cryptanalyse differential on reduced alternatives of SC2000 into 3 ½ or 4 ½ turns instead of the 6 basic ½. A weakness which makes it possible to extract up to 32 bits from the keys used for the first and the last tower of the version into 4 ½ turns.

References

T. Shimoyama, H. Yanami, K. Yokoyama, Mr. Takenaka, K. Itoh, J. Yajima, NR. Torii, and H. Tanaka, Proceedings off Fast Encryption Software - FSE' 01 , ED. Mr. Matsui, 2001.

External bonds

official Page of SC2000

Random links: