Cryptanalysis of an Image Block Encryption Algorithm Based on Chaotic Maps
This work exposes vulnerabilities in a specific image encryption method, with implications for many similar algorithms in the field.
The researchers analyzed a chaotic map-based image block encryption algorithm and found critical security flaws, demonstrating that an attacker could obtain an equivalent secret key using just five chosen plaintext-ciphertext pairs to decrypt other images.
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. In this paper, we give a thorough security analysis on the algorithm from the perspective of modern cryptology and report some critical security defects on the algorithm. Given five chosen plain-images and the corresponding cipher-images, 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.