An improved chaotic cryptosystem based on circular bit shift and XOR operations

A type of chaotic encryption scheme by combining circular bit shift with XOR operations was proposed in 2006 based on iterating chaotic maps. Soon after the proposal, it was cryptanalyzed and improved. Unfortunately, there are still two drawbacks in the two improved schemes. To strengthen the performance of the focused type of scheme, a new improved scheme based on Chenʼs chaotic system is proposed in this Letter. Simulation results and theoretical analysis show that our improved scheme is immune to information extracting by chosen plaintext attack and has expected cryptographic properties.

► There are 2 drawbacks in 2 improved chaos-based encryption schemes by bit shift & XOR operation.
► FIPS 140-2 test show the random number sequence generated by CCS is statistical random.
► The plaintext is first permuted byte by byte, and then masked in the inverse order.
► Small perturbation based on output ciphertext is given to c of CCS after iterating it every time.