面向混沌图像加密系统的密文分析方法  

Cryptanalysis method for chaotic image encryption system

作　　者：常晓琦 王明合 游大涛[1] 武相军[1] Chang Xiaoqi;Wang Minghe;You Datao;Wu Xiangjun(School of Software,Henan University,Kaifeng 475000,China)

机构地区：[1]河南大学软件学院,开封475000

出　　处：《中国图象图形学报》2024年第7期1934-1947,共14页Journal of Image and Graphics

基　　金：国家自然科学基金项目(61872125);河南省科技攻关(国际科技合作类)项目(182102410051);河南省自然科学基金项目(202300410038)。

摘　　要：目的 密文评估方法在衡量和增强混沌图像加密系统的安全性方面发挥着至关重要的作用。现有以密钥空间、密文密钥敏感性、像素个数变化率和统一平均变化强度等为代表的评估方法虽无法保证通过测试的加密系统一定具有非常高的安全性。而以选择明文攻击为代表的分析方法,与前者相比缺乏通用性和一致性,需要针对不同的加密系统设计不同的攻击方案。针对上述问题,本文基于深度学习模型面向混沌图像加密系统提出了一种兼具通用性和有效性的密文评估方法。方法 该方法的核心思路是以降噪自编码器为基础模型,使用编码器分别对图像加密方法中的扩散密文、置乱密文和完整加密密文进行深度表示,然后使用解码器以上述深度表示为输入生成相应的不同明文,最后统计该明文与真实明文间的结构相似度作为度量加密方法抵抗密码学常用攻击手段能力的量化指标。对于一个加密方法来说,不仅其完整加密密文必须完全不可破译,而且其置乱阶段和扩散阶段的密文中也必须有一项是完全不可破译的,否则表明加密方法存在严重的安全缺陷。另外,密文数据集是影响上述方法有效性的关键因素。针对该问题,本文提出了一种相关性密文生成方法,该方法充分利用了明文敏感性密钥的特性,确保了生成的密文和本文评估方法的真实性和有效性。结果 本文以Arnold置乱、2D-SCL(2D chaotic map based on the sine map,the chebyshev map and a linear function)加密和基于二维交叉混沌映射的量子加密为例对提出的密文评估方法进行了实验验证,实验中用到的数据集分别是MNIST(modified national institute of standards and technology database)和Fashion-MNIST。实验结果显示,本文提出的密文分析模型对上述加密方法及其各个阶段生成的密文图像表现出不同的密文分析能力:对Arnold置乱、2D-SCL扩散和�Objective Cryptography security analysis methods play a vital role in measuring and enhancing the security of chaotic image encryption systems.The existing ciphertext analysis methods for chaotic image encryption are generally divided into two categories.Although the evaluation methods based on numerical statistics,which are represented by key space analysis,sensitivity analysis of ciphertext to secret key,numbers of pixels change rate,and unified average changing intensity,have excellent versatility and consistency,the security of the test-passed encryption scheme cannot be ensured.While common attack methods in cryptography,which are represented by selective plaintext attack,can intuitively and effectively assess the security of chaotic encryption schemes,they lack versatility and consistency compared with security analysis methods,and different attack schemes need to be designed for different encryption schemes.To address the problem,this paper proposes a cryptanalysis method of chaotic image encryption system that is both versatile and effective based on denoising autoencoder.Method The ciphertext analysis method is improved based on the denoising autoencoder.It uses a cryptographic system with a known specific encryption steps to encrypt the plaintext image dataset and constructs the ciphertext analysis model,which takes the ciphertext image dataset as input and the original image dataset as the target data.The cryptanalysis model uses the encoder to obtain the depth representation of the diffusion ciphertext,scrambling the ciphertext and fully encrypted cipher image generated by the image encryption scheme,which is the structural features of images extracted from ciphertext images,and then uses the decoder to generate the different deciphered plaintext with the above depth representation as input.In this way,a deciphering model for a certain known encryption scheme can be trained,thereby achieving the purpose of ciphertext analysis.The effect of cryptanalysis is measured objectively and comprehensively by p

关 键 词：图像安全 密文分析 混沌图像加密系统 明文敏感性 深度学习 降噪自编码器 

分 类 号：TP309[自动化与计算机技术—计算机系统结构] TP18[自动化与计算机技术—计算机科学与技术]