Security Analysis of the GF-NLFSR Structure and Four-Cell Block Cipher

The overall structure is one of the most important properties of block ciphers. At present, the most common structures include Feistel structure, SP structure, MISTY structure, L-M structure and Generalized Feistel structure. In [29], Choy et al. proposed a new structure called GF-NLFSR (Generalized Feistel-NonLinear Feedback Shift Register), and designed a new block cipher called Four-Cell which is based on the 4-cell GF-NLFSR. In this paper, we first study properties of the ncell GF-NLFSR structure, and prove that for an n-cell GF-NLFSR, there exists an (n2 + n − 2) rounds impossible differential. Then we present an impossible differential attack on the full 25-round Four-Cell using this kind of 18-round impossible differential distinguisher together with differential cryptanalysis technique. The data complexity of our attack is

• Type: Conference
• Year: 2009
• Where: ICICS
• Authors: Wenling Wu, Lei Zhang, Liting Zhang, Wentao Zhang
• Keywords: Block Cipher, Communications, Feistel Structure, ICICS 2009, Overall Structure