Multi-Granularity Reversible Cellular Automata Applied in Data Encryption

Reversible cellular automata (RCA) can be applied in cryptography for its rule being an affine function. However, there are few number of traditional RCA which caused it is not suit for cryptography. In this paper, an extended RCA is proposed aimed to be applied in cryptography. In the RCA, each cell\´s transformation not only depend on current state but also rely on forepassed state. In order to improve the complexity of CA\´s dynamics, which is a crux in cryptography, traditional CA model is replaced by multi-granularity cellular automata (MGCA). Furthermore, a cryptography algorithm that based on multi-granularity reversible cellular automata (MG-RCA) is proposed. In the algorithm, cells have different granularity and can adjust their granularity dynamically by "splitrecombination" behavior during the process of encryption and decryption. The analysis results show that the cryptosystem can resist brute attack and differential attack, and also has high security. The hardware that shared by encryption and decryption caused the cryptosystem has a strong practicability.