Cryptanalysis of an Image Block Encryption Algorithm Based on Chaotic Maps

Abstract

Recently, an image block encryption algorithm was proposed based on some well-known chaotic maps. The authors claim that the encryption algorithm achieves enough security level and high encryption speed at the same time. However, we find that there are some critical security defects in the algorithm. In this paper, we give a thorough security analysis on the algorithm from the perspective of modern cryptography. Given one pair of known plain-image and its corresponding cipher-image, the attacker can obtain an equivalent secret key to successfully decrypt the other cipher-images encrypted with the same secret-key. In addition, each security metric adopted in the security evaluation on the algorithm is questioned. The drawn lessons are generally applicable to many other image encryption algorithms.