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A self-updating digital chaotic stream cipher

Chaotic cryptography has been extensively investigated over the past three decades, especially in the field of digital chaotic cryptography. In this paper, we propose a new digital chaotic stream cipher based on double piecewise linear chaotic maps. It initially takes four real numbers as the key, periodically updates the chaotic maps, and efficiently outputs the bit strings. Theoretical analysis shows that our protocol achieves higher anti-cryptanalysis capacities, effectively alleviates the dynamical degradation problem, and thus reaches higher security. Statistical evaluation demonstrates that our protocol can generate bit strings with outstanding statistical properties. In addition, we apply our protocol to image encryption and decryption. Experimental results verify the conclusions of the statistical evaluation, and prove the strong sensitivity of the protocol to the key.