Cryptanalysis and enhancements of image encryption using combination of the 1D chaotic map

Recently, a color image encryption using combination of the 1D chaotic map has been proposed by Pak et al. The encryption scheme has defined the new chaotic system structure, combined two Sine maps in the permutation stage, and utilized the key-streams generated by the Sine-Sine-map to confuse the permuted image. Then, linear transformation has been employed to permute the diffused image to obtain the encrypted image. However, by using Chosen-plaintext attack, we have found that the encrypted image can be completely cracked and this scheme is not applicable to secure communications. In this paper, the defects of the original algorithm have been analyzed and a Chosen plaintext attack has been proposed to crack the scheme. In addition, we propose an improved algorithm to overcome the defects in the above original algorithm. Experimental results show that the improved scheme can not only maintain the merits of the original one, but also resist the attacks.