Image encryption based on dynamic key and 2D chaos
Xingyu Chen, Yachao Wang, Xiaoran Lin · Journal of Electronic Imaging · 2025
As the demand for image data security continues to grow in distributed and real-time protection scenarios, traditional fixed-key image encryption methods face significant challenges due to key reuse, insufficient randomness, and limited resistance to attacks. To address these issues, we propose an adaptive dynamic key generation scheme based on timestamps and the password-based key derivation function 2 (PBKDF2) key derivation function. By leveraging the uniqueness of timestamps and the multi-iteration computation of PBKDF2, this scheme generates highly random, unpredictable, and non-repetitive encryption keys, effectively preventing key reuse and enhancing system security. Experimental results, evaluated using Hamming distance, correlation coefficients, and other metrics, demonstrate the strong randomness of these keys. To further enhance the dynamic nature and complexity of the encryption system, we introduce a tunable two-dimensional chaotic system that overcomes the limitations of traditional fixed-parameter chaotic maps. The core parameters of this system are perturbed by dynamic keys, ensuring that the chaotic trajectory is different for each encryption process, thereby avoiding periodic behaviors and improving ergodicity and randomness. Experimental analyses, including phase diagrams, 0-1 tests, Lyapunov exponents, and bifurcation diagrams, validate the system’s complexity, ergodicity, and broader parameter selection range, proving its strong randomness and resistance to analytical attacks. Building upon this foundation, we further propose a cross-plane image encryption algorithm. This algorithm breaks through the limitations of traditional single-plane pixel operations by utilizing a nonlinear chaotic sequence to drive bit-level scrambling, adaptively adjusting bit positions across multiple-bit planes. Compared with conventional methods, this approach completely disrupts the statistical correlation among pixels and avoids the security risks associated with fixed permutation patterns, ensuring that the encrypted image data exhibit stronger randomness and enhanced resistance to attacks. The experimental results of the encryption algorithm demonstrate that this scheme exhibits excellent security in terms of correlation analysis and information entropy.