Abstract:
In the recent literature, many research studies have proven that Known and Chosen plaintext attacks are very efficient tools that are widely used to cryptanalyze partially
or completely some chaos-based and non-chaos cryptosystems. In this paper, we addressed
some weaknesses in the first Zhang et al., cryptosystem “An image encryption scheme
using reverse 2-dimensional chaotic map and dependent diffusion”. First, we analyzed the
encryption process of Zhang et al., and we found that the non-linear diffusion process can
be removed because its argument is present in the ciphered image. Then, based on this
observation we derived a partial cryptanalysis equation that removes the effect of the diffusion function and accordingly permits to recover the permuted version of the ciphered
image. As a result of the previous operation, the brute-force attack became more suitable. In addition, we mounted a chosen plaintext attack based on a proposed chosen plain
image. Consequently, the encryption key space is reduced or recovered for one round,
also, the average values of NPCR and UCAI randomness parameters become small compared to the optimal values, and moreover, they are very low for specific pixel position
attacks.
