Cryptanalyzing a RGB image encryption algorithm based on DNA encoding and chaos map

•This paper re-evaluates the security of a RGB image encryption algorithm based on DNA encoding and chaos map.•The image encryption algorithm can be broken with only one known plain-image.•Two more security weaknesses of the encryption algorithm, low sensitivity with respect to changes of plaintext and secret key, are given.

Recently, a RGB image encryption algorithm based on DNA encoding and chaos map has been proposed. It was reported that the encryption algorithm can be broken with four pairs of chosen plain-images and the corresponding cipher-images. This paper re-evaluates the security of the encryption algorithm, and finds that the encryption algorithm can be broken efficiently with only one known plain-image. The effectiveness of the proposed known-plaintext attack is supported by both rigorous theoretical analysis and experimental results. In addition, two other security defects are also reported.