WU Wen-Ling, Associate Editor-in-Chief of Journal of Cryptologic Research, Professor of Trusted Computing and Information Assurance Laboratory, Institute of Software, Chinese Academy of Sciences

The SIMON algorithm is a lightweight block cipher released by the National Security Agency (NSA) in 2013. It supports multiple block sizes and key sizes, has excellent software and hardware implementation performance, and can meet the security requirements of various application environments. The encryption round function of the SIMON algorithm is very concise, and it only includes cyclic shift, bitwise AND, and bitwise XOR operation, which has become the imitation object of some cryptographic algorithm design. Until now, the NSA has not disclosed the design principles of the SIMON algorithm and the results of security self-assessment, therefore, the SIMON algorithm has attracted research interest in the cryptographic community. Some scholars, based on equivalent subsets and computer searching, pointed out that the selection of the parameters of the SIMON algorithm was not optimal. This work, published in the Journal of Cryptologic Research in 2019, studies the equivalent subsets of SIMON-like algorithms, theoretically proves the relationship between the number of equivalent subsets and the block size of 2n, and gives the concrete expression of representative of algorithm equivalent class, the complexity is reduced from the whole space O(n3) to O(n2). The counting method of equivalent subsets described in this article can be extended to cryptographic algorithms with similar structures. The reduction of search space and the representation method of representative are helpful for the design and security evaluation of similar cryptographic algorithms. 

Article

Research on equivalent class of SIMON-like cipherparameters  

Cite

ZHANG Y, LIU G Q, LI C. Research on equivalent class of SIMON-like cipherparameters[J]. Journalof Cryptologic Research, 2019, 6(3): 293–303. [DOI: 10.13868/j.cnki.jcr.000303