Cryptanalyzing a novel couple images encryption algorithm based on DNA subsequence operation and chaotic system

Recently, a novel couple images encryption algorithm based on DNA subsequence operation and chaotic system has been proposed. This paper evaluates the security of this encryption algorithm. The main weakness of the encryption algorithm is that the generated pesudo-random number sequences remain unchanged for encrypting every image. Based on this flaws, the present paper proposed a chosen-plaintext attack to reveal the equivalent keys with some pairs of chosen-plaintext and the corresponding ciphertext. Finally, the experimental results are provided to support the proposed attack.