  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.
