Breaking a novel colour image encryption algorithm based on chaos

TL;DR

This paper critically evaluates a chaos-based color image encryption algorithm, revealing vulnerabilities that allow its parts to be broken with minimal chosen-plaintext attacks, supported by theoretical and experimental analysis.

Contribution

It provides a security analysis demonstrating that the proposed encryption algorithm can be compromised with simple chosen-plaintext attacks, exposing its vulnerabilities.

Findings

Position permutation can be broken with one chosen plaintext.

Substitution part can be broken with two chosen plaintexts.

Theoretical analysis supports the feasibility of the attacks.

Abstract

Recently, a colour image encryption algorithm based on chaos was proposed by cascading two position permutation operations and one substitution operation, which are all determined by some pseudo-random number sequences generated by iterating the Logistic map. This paper evaluates the security level of the encryption algorithm and finds that the position permutation-only part and the substitution part can be separately broken with only $\lceil (\log_2(3MN))/8 \rceil$ and 2 chosen plain-images, respectively, where $MN$ is the size of the plain-image. Concise theoretical analyses are provided to support the chosen-plaintext attack, which are verified by experimental results also.