[Paper Review] A Fast Image Encryption Scheme based on Chaotic Standard Map

Kwok‐Wo Wong, Bernie Sin-Hung Kwok+1 more|ArXiv.org|Sep 29, 2006

Chaos-based Image/Signal Encryption6 references4 citations

TL;DR

This paper proposes a fast image encryption scheme using the chaotic standard map to enhance security with reduced encryption time. By integrating diffusion-like effects into the confusion stage via sequential add-and-shift operations, the method reduces reliance on separate diffusion stages, cutting encryption time to less than one-third of existing schemes while maintaining comparable security performance.

ABSTRACT

In recent years, a variety of effective chaos-based image encryption schemes have been proposed. The typical structure of these schemes has the permutation and the diffusion stages performed alternatively. The confusion and diffusion effect is solely contributed by the permutation and the diffusion stage, respectively. As a result, more overall rounds than necessary are required to achieve a certain level of security. In this paper, we suggest to introduce certain diffusion effect in the confusion stage by simple sequential add-and-shift operations. The purpose is to reduce the workload of the time-consuming diffusion part so that fewer overall rounds and hence a shorter encryption time is needed. Simulation results show that at a similar performance level, the proposed cryptosystem needs less than one-third the encryption time of an existing cryptosystem. The effective acceleration of the encryption speed is thus achieved.

Motivation & Objective

• To reduce the computational overhead of chaos-based image encryption by minimizing redundant diffusion stages.
• To accelerate encryption speed without compromising security by introducing diffusion effects during the confusion phase.
• To propose a lightweight, efficient encryption architecture suitable for real-time image transmission.
• To validate the scheme's performance through simulation and comparison with existing methods.

Proposed method

• The scheme uses the chaotic standard map to generate pseudo-random sequences for confusion and diffusion operations.
• A novel add-and-shift operation is applied sequentially during the confusion stage to induce partial diffusion effects.
• Confusion and diffusion are no longer strictly separated; instead, diffusion is embedded in the confusion process to reduce the number of required rounds.
• The method leverages the ergodic and sensitive dependence properties of the standard map for strong cryptographic randomness.
• The algorithm is designed to be computationally efficient, minimizing arithmetic operations while maximizing security.
• The scheme is evaluated using standard image encryption metrics and compared against a reference system with identical security levels.

Experimental results

Research questions

• RQ1 Can diffusion effects be effectively introduced during the confusion stage to reduce the need for separate diffusion rounds?
• RQ2 To what extent can encryption speed be improved by modifying the traditional confusion-diffusion structure?
• RQ3 How does the proposed scheme compare to existing chaos-based image encryption systems in terms of security and performance?
• RQ4 Does the integration of add-and-shift operations preserve the required cryptographic properties of confusion and diffusion?
• RQ5 What is the optimal balance between security and speed in a chaos-based image encryption framework?

Key findings

• The proposed scheme achieves less than one-third of the encryption time required by an existing cryptosystem at a similar security level.
• The integration of diffusion-like operations into the confusion stage significantly reduces the number of overall rounds needed.
• Simulation results confirm that the scheme maintains strong confusion and diffusion properties despite architectural simplification.
• The use of sequential add-and-shift operations effectively introduces diffusion without requiring additional computational stages.
• The method demonstrates high efficiency and is suitable for real-time image encryption applications.
• The chaotic standard map provides sufficient randomness and sensitivity to initial conditions for robust security.