This paper presents a detailed security analysis of the research article on the digital image encryption scheme entitled "Reversible Logic Cryptography Design (RLCD) with Linear Feedback Shift Register (LFSR) key" (Karunamurthi S, and Natarajan VK, Microprocessors and Microsystems, 2019). Although the inadequate length of its 4-bit LFSR key makes the scheme extremely vulnerable to quick brute force attack, analyzing the various error metrics concerning the security of the encrypted images, this scheme provides statistically pleasing results. The major shortcoming identified on this RLCD-LFSR scheme is the traceable patterns that appear on its encrypted images due to the absence of confusion to break the pixels' correlation. In addition to the chosen plaintext attack, edge detection based cryptanalysis proposed in this paper to be sufficient to crack the RLCD-LFSR scheme. The enhancement made by the insertion of a confusion module in RLCD-LFSR scheme wipes out the perceptible patterns and edges from the encrypted images to resist the attacks. The failure of enhanced RLCD-LFSR under NIST tests confirms the flaws in the design of the Reversible Logic Gate (RLG) based diffusion process and its ineffectiveness for image encryption. Besides the security analysis, the performance of RLCD-LFSR scheme and the proposed improved version of the same is implemented on a 32-bit microcontroller to evaluate their suitability for real-time embedded applications.

本文介绍了有关数字图像加密方案的研究文章的详细安全性分析，该方案名为``具有线性反馈移位寄存器（LFSR）密钥的可逆逻辑密码学设计（RLCD）''（Karunamurthi S和Natarajan VK，微处理器和微系统，2019年） 。尽管其4位LFSR密钥的长度不足，使得该方案极易受到快速蛮力攻击，但分析了有关加密图像安全性的各种错误指标，但该方案提供了令人愉悦的统计结果。在RLCD-LFSR方案上发现的主要缺点是，由于没有混淆来破坏像素的相关性，因此在其加密图像上出现了可追踪的图案。除了选择的明文攻击之外，本文提出的基于边缘检测的密码分析方法足以破解RLCD-LFSR方案。通过在RLCD-LFSR方案中插入混淆模块而进行的增强消除了加密图像中可感知的图案和边缘，从而抵御了攻击。在NIST测试下，增强型RLCD-LFSR的失败证实了基于可逆逻辑门（RLG）的扩散过程设计中的缺陷及其对图像加密的无效性。除了安全性分析之外，RLCD-LFSR方案的性能及其建议的改进版本在32位微控制器上实现，以评估其对实时嵌入式应用的适用性。通过在RLCD-LFSR方案中插入混淆模块而进行的增强消除了加密图像中可感知的图案和边缘，从而抵御了攻击。在NIST测试下，增强型RLCD-LFSR的失败证实了基于可逆逻辑门（RLG）的扩散过程设计中的缺陷及其对图像加密的无效性。除了安全性分析外，RLCD-LFSR方案的性能及其建议的改进版本在32位微控制器上实现，以评估其对实时嵌入式应用的适用性。通过在RLCD-LFSR方案中插入混淆模块而进行的增强消除了加密图像中可感知的图案和边缘，从而抵御了攻击。在NIST测试下，增强型RLCD-LFSR的失败证实了基于可逆逻辑门（RLG）的扩散过程设计中的缺陷及其对图像加密的无效性。除了安全性分析外，RLCD-LFSR方案的性能及其建议的改进版本在32位微控制器上实现，以评估其对实时嵌入式应用的适用性。