Abstract:

CRYPTON V1.0 is a block cipher with a 128bit block size and a 128bit key size. The linear layer of CRYPTON V1.0 is designed based on bits, therefore integral attacks in a traditional way are of no value. In this paper, CRYPTON V1.0 is analyzed. We trace the propagation of the plaintext structure at the bitlevel to obtain the property, present a 3round distinguisher and test it on the PC. In the distinguisher, 1024 chosen plaintexts are encrypted by a 3round cipher, and each bit of the cipher text is balanced. Based on this distinguisher, the reducedround CRYPTON V1.0 is attacked. The result shows a 4round attack needs  211 chosen plaintexts and 223 encryptions, a 5round attack needs 212.4 chosen plaintexts and 253 encryptions.

Key words: block cipher;integral attack;CRYPTON V1.0;bitpattern