Abstract: Aiming at the speed of encryption and decryption of existing image encryption algorithms， a fast image encryption algorithm combined with DNA encoding is proposed using the chaotic sequence generated by the new 4-D chaotic system as the index sequence to indicate the specific position to be exchanged during the permutation process. DNA encoding is performed on the permuted image， and the diffusion process is completed by the DNA addition and DNA XOR of rule 1， then different rules are used for DNA decoding to complete the secondary encryption.The experimental results show that the proposed method reduces the number of loop traversals of permutation process while ensuring the security of the image encryption system， thereby increasing the speed of encryption and decryption.

Key words: image encryption; DNA encoding; permutation; diffuse; chaotic system