Cryptanalyzing and Improving a Novel Color Image Encryption Algorithm Using RT-Enhanced Chaotic Tent Maps

In recent years, chaos-based image encryption algorithms have aroused extensive research interest. However, some image encryption algorithms still have several security defects, and the research on cryptanalysis is relatively inadequate. This paper performs the cryptanalysis of a newly proposed color image encryption scheme using RT-enhanced chaotic tent map. By using chosen-plaintext attacks, the equivalent keys of the cryptosystem are successfully broken, so that the target ciphertext image can be decoded. Based on the cryptanalysis, we then proposed an improved encryption algorithm. A new logistic-tent map is proposed and applied to the improved encryption algorithm, and a parameter related to the SHA-3 hash value of the plaintext image is introduced as a secret key parameter so that the improved algorithm can resist chosen-plaintext attacks. The security analysis and experimental tests for the improved algorithm are given in detail, which show that the improved algorithm can significantly increase the security of encryption images while still possessing all the merits of the original algorithm.