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.