面向云环境的彩色图像混合加密算法

针对传统图像加密算法难以保证在云环境下密钥配送的安全性,以及DNA编码在抗统计学分析效果欠佳等问题提出了一种面向云环境的彩色图像混合加密算法。提出了一种自适应DNA编码对传统方法进行改善,通过国产SM2与SM3加密算法作为散列值的生成函数与控制参数的非对称加密,运用盲水印技术镶嵌至密文图像中。实验结果表明,该算法密钥空间大且加密图像相邻像素相关性较低,具有更为接近理想值的像素改变率与像素平均改变强度,具有较为理想的安全性同时在密钥的传输过程中由非对称加密算法保证其安全可靠。     

High-capacity reversible data hiding in encrypted image based on specific encryption process

This paper proposes a novel reversible data hiding method in encrypted images based on specific encryption process. In the proposed specific encryption algorithm, the stream cipher and prediction error are combined to vacate room for data embedding. After that, a permutation operation is performed on the encrypted image to improve the security. In the embedding process, we can embed a large amount of secret data in the encrypted image by pixel value expansion because most of the pixel values are less than 128 by the specific encryption process. At the receiver end, the encrypted image can be recovered from the marked encrypted image without knowing the secret data. Therefore, even if the recipient only has the encryption key, the original image will be perfectly recovered. If the recipient only has the data-hiding key, the secret data will be extracted. And if the recipient has both keys, the original image and the secret data are both available. The proposed method achieves a higher embedding capacity than that of methods based on vacating room after encryption. It does not require the image owner to perform reversible data hiding techniques on the original image, which is more convenient than methods based on reserving room before encryption. Experimental results demonstrate that the proposed method outperforms other state-of-the-art methods.     

A fast color image encryption algorithm based on coupled two-dimensional piecewise chaotic map

In recent years, a variety of chaos-based image cryptosystems have been proposed. Owing to the exceptionally desirable properties of mixing and sensitivity to initial conditions and parameters of chaotic maps, chaos-based encryption has suggested a new and efficient way to deal with the intractable problem of fast and highly secure image encryption. This paper proposes a novel chaos-based image encryption algorithm to encrypt color images by using a Coupled Two-dimensional Piecewise Nonlinear Chaotic Map, called CTPNCM, and a masking process. Distinct characteristics of the algorithm are high security, high sensitivity, and high speed that can be applied in encryption of color images. In order to generate the initial conditions and parameters of the CTPNCM, 256-bit long external secret key is used. Computer simulations confirm that the new algorithm has high security and is very fast for practical image encryption. It is demonstrated that the number of pixel change rate (NPCR), the unified average changing intensity (UACI), and entropy can satisfy security and performance requirements (NPCR>0.99672, UACI>0.334904, Entropy>7.99921). Experimental results reveal the fact that the proposed algorithm yields better security performance in comparison to the results obtained from other algorithms.     

Reversible data hiding in Paillier cryptosystem

In this paper, reversible image data hiding in the Paillier cryptosystem is investigated. To transmit additional data in homomorphic encryption domain, two algorithms are proposed for different application scenarios. By exploiting the additive homomorphism, high-capacity data hiding can be accomplished with the first algorithm by conducting value expansion on the encrypted pixel values. But the hidden data can only be extracted after image decryption (i.e., in plain-text domain). With the second algorithm, both of data embedding and extraction can be performed in the encryption domain by exploiting the self-blinding property, while the corresponding plain-text values are unchanged. Compared with the reversible data hiding algorithms designed for encryption with a cipher stream, the proposed ones are more applicable in cloud computing without degrading the security level. Thus the additional data can be losslessly transmitted in the different applications of Paillier cryptosystem.     

A Study of Steganographic Image Security

In this dissertation, sereral key problems in the field of steganographic image security are mainly studied and discussed: (1) A novel kind of image cryptosystem is studied. The encrypted information of secret image is embedded into an ordinary image, which can be transmitted publicly, and it will not cause attention of illegal eavesdropper. The following results are achieved: (a) The image hiding algorithm and its improved algorithm based on wavelet transform and vector quantization are propo…     

基于双文本段的信息隐藏算法

信息隐藏是一种在传输或存储过程中将隐秘信息隐藏在特定载体中,以保证隐秘信息安全性的技术。常用的载体有图像、音频、视频、文本等类型文档。由于文本文档特别是纯文本文档中的冗余信息非常少,基于纯文本文档的信息隐藏具有很大的挑战性。现存的基于纯文本文档的算法都是基于单文本段的,在安全性方面还存在许多难以克服的缺陷。该文提出了一种新的基于双文本段的信息隐藏算法,通过在多种隐藏形式中选择适当的隐藏形式和信息分散存储,大大地提高信息隐藏的隐蔽性、安全性。另外,算法具有很高的灵活度,可以根据具体的应用情景进行适当的变形或调整,以便更好地适用于实际需求。     

A Steganography-Based Optical Image Encryption System Using RGB Channel Integration

An optical image encryption system with adaptive steganography using red, green, and blue (RGB) channel integration is proposed. The optical image encryption system employs a double random phase encoding algorithm to encrypt and decrypt color images. The RGB channel in a color image is first integrated into a large grayscale image. Then the integrated image is encrypted by two random phase masks. The secret data is then embedded into the encrypted image with a specific hiding sequence generated by the zero-LSB (least significant bits) sorting technique which is a content-dependent and low distortion data embedding method. Experimental results show that the proposed method has a good performance in both hiding capacity and decrypted image quality.     

基于随机变换的大容量隐藏算法

主要研究利用图像低位平面数据位的运算来减小对载密图像修改的信息隐藏算法.在嵌入信息时对秘密信息进行连续多次随机变换的同时与载体信息进行位运算,以此求出对载体图像修改量最小的嵌入方式.从而实现在相同嵌入量的条件下尽量减少对载体图像的修改,提高了载密图像的质量.实验结果表明,该算法能有效地减少载体图像的失真,在嵌入大量信息...     

基于 RSA 与 LSB 算法的信息隐藏

信息隐藏技术将特定信息嵌入数字化宿主信息中,由于宿主信息呈现变化不大,不会引起监控者的注意和重视,从而减少了被攻击的可能性。为了提高信息隐藏效率与在非授权情况下提取信息的难度,提出将信息加密后进行隐藏,具有更高的安全性。在信息隐藏前对敏感信息进行了信息分割、RSA加密预处理;将控制信息也嵌入到BMP文件的图像数据区;实现了改进的LSB算法,并通过实验进行了验证。     

An enhanced chaotic key‐based RC5 block cipher adapted to image encryption

RC5 is a block cipher that has several salient features such as adaptability to process different word lengths with a variable block size, a variable number of rounds and a variable‐length secret key. However, RC5 can be broken with various attacks such as correlation attack, timing attack, known plaintext correlation attack and differential attacks, revealing weak security. We aimed to enhance the RC5 block cipher to be more secure and efficient for real‐time applications while preserving its advantages. For this purpose, this article introduces a new approach based on strengthening both the confusion and diffusion operations by combining chaos and cryptographic primitive operations to produce round keys with better pseudo‐random sequences. Comparative security analysis and performance evaluation of the enhanced RC5 block cipher (ERC5) with RC5, RC6 and chaotic block cipher algorithm (CBCA) are addressed. Several test images are used for inspecting the validity of the encryption and decryption algorithms. The experimental results show the superiority of the suggested enhanced RC5 (ERC5) block cipher to image encryption algorithms such as RC5, RC6 and CBCA from the security analysis and performance evaluation points of view.     

基于变步长约瑟夫遍历和DNA动态编码的图像加密算法的安全性分析

近年来,不断有新的图像加密算法被提出,其安全性却未得到充分的分析和验证。该文对一种最新报道的图像加密算法的安全性进行了分析。所分析算法通过基于变步长约瑟夫遍历的像素置乱、基于DNA动态编码的像素替换及像素行列扩散来完成图像加密。分析表明,该算法的秘密密钥设计不具有实用性,加密过程也存在缺陷。在选择明文攻击条件下,对该算法的加密过程进行了密码分析,并提出了相应的攻击算法。仿真实验和理论分析确认了所提攻击算法的有效性与可行性。最后,针对所分析算法及部分图像加密算法中存在的问题,提出了改进建议。     

基于信息分存的整数小波大容量数据隐藏方法

针对基于变换域的数据隐藏算法容量较小、提取时需要原始图像的问题,提出一种小波域的大容量隐藏盲提取算法。利用混沌序列和分组异或对隐秘信息加密,进而将隐秘信息分解为不完全商和余数,然后将不完全商和余数分存于载体图像的低频和高频系数中,并对溢出进行处理。实验表明:在灰度图像中数据隐藏量(SHR)达到37.5%,峰值信噪比(PSNR)可保持在39 dB以上,直方图无异常;通过混沌加密,使得隐秘信息具有较好的伪随机特征,安全性好。     

A Chaotic System Based Image Encryption Scheme with Identical Encryption and Decryption Algorithm

A new symmetric key image encryption scheme based on hyper-chaotic Lorenz system is proposed.The encryption process and the decryption process are identical in the proposed scheme.They both include two diffusion operations,one plaintext-related scrambling operation and three matrix rotating 180 degrees operations.The hyper-chaotic Lorenz system is employed to generate the secret code streams to encrypt the plain image,and to implement the diffusion process with XOR operation.The plaintext-related scrambling is used in this scheme to make different plain images correspond to different secret code streams even when the secret keys are the same,so that the scheme can fight against the chosen/known plaintext attacks.Simulation results show that the proposed scheme has the merits of high encryption speed,large key space,strong key sensitivity,strong plaintext sensitivity,good statistical properties of cipher-text,and etc.,and can be used in practical communications.     

基于三维超混沌系统的彩色图像加密算法

针对彩色图像的存储特性,为了改进彩色图像加密算法的安全性和效率,提出了一种基于三维超混沌系统的彩色图像加密算法.该算法利用改进的三维超混沌系统产生混沌序列,采用复合加密算法实现彩色图像在空域上的加密.使用MATALAB7.0进行仿真实验.理论分析和实验表明,该算法具有良好的保密性和加密效果.若进一步降低运算量,该算法可对诸如军事卫星图片、商业机密图纸、远程私人病历等需要保密通信的场合有广泛的应用前景.     

Encrypted signal-based reversible data hiding with public key cryptosystem

Encrypted image-based reversible data hiding (EIRDH) is a well-known method allowing that (1) the image provider gives the data hider an encrypted image, (2) the data hider embeds the secret message into it to generate the encrypted image with the embedded secret message to the receiver, and (3) finally the receiver can extract the message and recover the original image without encryption. In the literature, the data hider and image provider must be specific parties who know the shared key with the receiver in traditional encrypted image-based reversible data hiding. In this paper, we propose an encrypted signal-based reversible data hiding (ESRDH) with public key cryptosystem, not only for images. The proposed scheme is secure based on Paillier homomorphic encryption. Finally, the experimental results show that the proposed scheme has much payload and high signal quality.     

数字图像信息隐藏技术研究

阐述了信息隐藏的基本概念及其与信息加密的区别,给出了用数字图像作为掩护媒体的信息隐藏算法,为了提高信息隐藏的安全性,引入了混沌序列对秘密信息进行加密的方法,实验结果表明,算法很好的实现了信息隐藏功能。     

多级秘密信息隐藏方法

针对普通的一级秘密信息隐藏的方法具有安全性低,视觉效果差的问题,本文提出了一种多级别信息隐藏的方法.该方法使一级秘密信息在一级密钥作用下成为宿主图像,提高了信息隐藏的安全性,再将宿主图像分成3×3的图像块,在二级密钥的控制下成功将二级秘密信息嵌入.采用图像置乱和LSB算法的结合方法,并在两级秘密信息的作用下,使得载密图...     

一种基于交替密钥的分组结构彩色图像加密算法

基于循环迭代的加/解密机制,提出了一种新的彩色图像加密算法。该算法在彩色空间应用了仿射变换,将交替密钥生成算法与分组结构引入到彩色图像加密过程,采用二种混沌映射对彩色图像加密,在每一次交替加密过程中,通过对初始密钥循环移位生成相应的交替密钥并产生二种子密钥,用于二种混沌映射,从而增加了密钥空间,有效提高了彩色图像加密算法的安全性。实验结果表明,该彩色图像加密算法安全性好,免疫性强,效率高。     

Efficient multi-secret image sharing based on Boolean operations

(n,n) visual secret sharing (VSS), first proposed by Naor and Shamir (1995) [4], is used to encode (encrypt) a secret image into n meaningless share images to be superimposed later to decode (decrypt) the original secret by human visual system after collecting all n secret images. In recent years, VSS-based image sharing (encryption) and image hiding schemes, two of a variety of applications based on VSS, have drawn much attention. In this paper, an efficient (n+1,n+1) multi-secret image sharing scheme based on Boolean-based VSS is proposed to not only keep the secret images confidential but also increase the capacity of sharing multiple secrets. The Boolean-based VSS technology, used to encode the secret images, generates n random matrices; then the n secret images are subsequently encoded into the n+1 meaningless share images. It is worthwhile to note that n secret images can be hidden by means of sharing only n+1 share images in the proposed scheme instead of 2n share images. Thus, the present scheme thus benefits from (1) reducing the demand of image transmission bandwidth, (2) easing the management overhead of meaningless share images, and (3) involving neither significant extra computational cost nor distortion for reconstructed secret images. The experimental results show the performance in terms of feasibility and image sharing capacity. Applied into image hiding schemes, the proposed scheme can enhance the hiding capacity.     

信息隐藏技术及其应用

阐述了信息隐藏技术的基本原理、信息隐藏系统的一般模型和设计要求，分析了信息隐藏技术的两个主要分支——隐写术和数字水印对性能指标的不同要求，探讨了以数字图像作为载体的隐藏算法的实现方法，以及信息隐藏技术在通信保密和版权保护等方面的应用。