Enhanced RC5 Key Schedule Using One-Dimensional Cellular Automata for Audio File Encryption

Abstract

Audio security is an important aspect in various areas of communication. This paper deals with audio encryption as many of the data communication depends on audio data.  In this paper, a new proposal of audio encryption system has been introduced. The system can be divided into two phases, the first phase focuses on generating a high-quality Pseudo Random Number generator (PRNGs) using elementary, periodic and hybrid rules of cellular automata (CA). The system suggests a new combination of CA rules in an endeavor to provide high randomness and to improve the strength of the proposed cryptosystem. Whereas the second phase produces the Enhanced Rivest Cipher 5 (ERC5) algorithm which employs the generated Random Number Sequence (RNS) in an effort to strengthen the security and randomness of the original Rivest Cipher 5 (RC5) algorithm.

The results show that the proposed PRNGs based on CA can generates RNS with a high period which can reach to more than 100,000 keys without repetition or string duplication. Moreover, the tests demonstrates that the proposed ERC5 improves the security of the original RC5 algorithm. The proposed cryptosystem is evaluated in terms of Shannon theory of information entropy, randomness tests, computation time and key space analysis. The results verify that the suggested audio crypto-system increases the growth of the security level of original RC5 encryption algorithm with high degree of randomness and confidentiality.