图象加密日益受到重视,许多加密算法被提出,其中一维混沌加密算法由于利用了混沌序列的良好复杂性、伪随机性和对初值的敏感特性而具有较好的加密性能,但与其他方法比较,其最大的缺陷是密钥空间太小.为此研究了一种基于二维超混沌系统的图象加密新方法,设计了若干个形式简单的二维超混沌模型,把它们生成的混沌序列变换成加密因子序列,采用纵横两重逐位模2加运算来加密、解密图象.实验研究表明,该方法加密速度快,密钥空间增大,抗破译强度提高,并有一定抗破损鲁棒性.

The security of digital images attracts much attention recently, and many image encryption methods have been proposed. Among them, the ID chaotic image encryption method was reported with appropriate performances by using the appropriate complexity and pseudo-randomness and extreme parameter sensitivity of chaotic sequences but with smaller key space as its serious drawback compared with others. So a new image encryption algorithm based on hyperchaotic sequences is studied. Several fast simple 2D hyperchaotic systems are given and studied. A linear approach of mapping from the model parameters to the key is proposed in order to make full use of the key space and keep the correspondency between the key and the model parameters used for encryption, The chaotic sequences generated by these models are mapped into the encrypt sequences, then the image is encrypted by the encrypt sequences by using two directional XOR horizontally and vertically. Experimental results show that this method is effecient, witch can provide faster encryption and larger key space and stronger anti-decryption-ability and rubustness to local breakage compared with the 1-D chaotic image encryption.