关键词: 混沌, 图像加密, 变长密钥, 一次密钥流

Abstract: Traditional image encryption algorithms have some shortcomings such as weak theory about key generating, fixed-length key, limited key-value range. Aiming at these disadvantages, a variable-length running key image encryption algorithm with solid theory foundation is proposed. At first, uniform trend theorem and the deviation theorem are given, then according to these theorems, uniform generation algorithm of chaotic sequence is designed, which is used to generate uniform distribution random number. On this basis, this random number is used to generate the length of plain-text and corresponding length key. At last, variable-length key image encryption scheme with one-time key stream is implemented by using cipher-text disturbance chaotic sequence and random feedback encryption technique. Theory analysis and experimental results show that the proposed image encryption algorithm not only inherits the merit of one-time key of traditional encryption scheme, but also increases the difficulty of crack and enhances the security of image encryption algorithm since solid theory, variable-length encryption mechanism and key space and its value flexibility.

Key words: chaos, image encryption, variable-length key, one-time key stream