The objective of this paper is to give a comprehensive introduction to applied cryptography with an engineer or computer scientist in mind. The emphasis is on the knowledge needed to create practical systems which supports integrity, confidentiality, or authenticity. Topics covered includes an introduction to the concepts in cryptography, attacks against cryptographic systems, key use and handling, random bit generation, encryption modes, and message authentication codes. Recommendations on algorithms and further reading is given in the end of the paper. This paper should make the reader able to build, understand and evaluate system descriptions and designs based on the cryptographic components described in the paper.

[서평]「Applied Cryptography」

Encryption of images is different from that of texts due to some intrinsic features of images such as bulk data capacity and high redundancy, which are generally difficult to handle by traditional methods. Due 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. In this paper, the two-dimensional chaotic cat map is generalized to 3D for designing a real-time secure symmetric encryption scheme. This new scheme employs the 3D cat map to shuffle the positions (and, if desired, grey values as well) of image pixels and uses another chaotic map to confuse the relationship between the cipher-image and the plain-image, thereby significantly increasing the resistance to statistical and differential attacks. Thorough experimental tests are carried out with detailed analysis, demonstrating the high security and fast encryption speed of the new scheme.

A symmetric image encryption scheme based on 3D chaotic cat maps

In recent years, a large amount of work on chaos-based cryptosystems have been published. However, many of the proposed schemes fail to explain or do not possess a number of features that are fundamentally important to all kind of cryptosystems. As a result, many proposed systems are difficult to implement in practice with a reasonable degree of security. Likewise, they are seldom accompanied by a thorough security analysis. Consequently, it is difficult for other researchers and end users to evaluate their security and performance. This work is intended to provide a common framework of basic guidelines that, if followed, could benefit every new cryptosystem. The suggested guidelines address three main issues: implementation, key management and security analysis, aiming at assisting designers of new cryptosystems to present their work in a more systematic and rigorous way to fulfill some basic cryptographic requirements. Meanwhile, several recommendations are made regarding some practical aspects of analog chaos-based secure communications, such as channel noise, limited bandwith and attenuation.

/pdf/some-basic-cryptographic-requirements-for-chaos-based-4qsyrod8nl.pdf

Some basic cryptographic requirements for chaos-based cryptosystems

Image encryption using chaotic logistic map

https://ir.nctu.edu.tw:443/bitstream/11536/29805/1/000166438300010.pdf

Image hiding by optimal LSB substitution and genetic algorithm

The security of digital images attracts much attention recently, and many image encryption methods have been proposed. In IS-CAS2000, a new chaotic key-based algorithm (CKBA) for image encryption was proposed. This paper points out CKBA is very weak to the chosen/known-plaintext attack with only one plain-image, and its security to brute-force ciphertext-only attack is overestimated by the authors. That is to say, CKBA is not secure at all from cryptographic viewpoint. Some experiments are made to show the feasibility of the chosen/known-plaintext attack. We also discuss some remedies to the original scheme and their performance, and we find none of them can essentially improve the security of CKBA.

/pdf/cryptanalysis-of-a-chaotic-image-encryption-method-zcmswuvwhw.pdf

Cryptanalysis of a chaotic image encryption method

Many digital services, such as pay TV, confidential videoconferencing, and medical and military imaging systems, require reliable security in storage and transmission of digital images and videos. This chapter focuses on different image and video encryption algorithms based on chaos and aims to clarify some experiences, lessons, and principles of using chaos to design such encryption schemes. In image and video encryption systems, some features are required to support special functions of diverse multimedia services in different environments. Since the 1990s, selective encryption has been widely suggested and adopted as a basic idea for the encryption of digital images and videos, aiming to achieve a better trade-off between the encryption load and the security level. Image and video encryption plays a more and more important role in today’s multimedia world. Although many encryption schemes have been proposed to provide security for digital images and videos, some of them are too weak to resist various attacks designed by cryptanalysts.

Chaos-Based Encryption for Digital Images and Videos

In this paper, we propose a novel video encryption scheme based on multiple digital chaotic systems, which is called CVES (Chaotic Video Encryption Scheme). CVES is independent of any video compression algorithms, and can provide high security for real-time digital video with fast encryption speed, and can be simply realized both by hardware and software. Whats more, CVES can be extended to support random retrieval of cipher-video with considerable maximal time-out; the extended CVES is called RRS-CVES (Random-Retrieval-Supported CVES). Essentially speaking, CVES is a universal fast encryption system and can be easily extended to other real-time applications. In CVES, 2^n chaotic maps are used to generate pseudo-random signal to mask the video, and to make pseudo-random permutation of the masked video. Another single chaotic map is employed to initialize and control the above 2^n chaotic maps. Detailed discussions are given to estimate the performance of CVES/RRS-CVES, respectively from the viewpoints of speed, security, realization and experiments.

/pdf/chaotic-encryption-scheme-for-real-time-digital-video-hxvhkkxod4.pdf

Chaotic encryption scheme for real-time digital video

The security of digital images has attracted much attention, and many different image encryption methods have been proposed. Yen and Guo (see Proc. IEEE Workshop Signal Processing Systems, p.430-37, 1999) proposed a novel image encryption algorithm called BRIE (bit recirculation image encryption). This paper points out that BRIE is not secure enough from strict cryptographic viewpoint. It has been found that some defects exist in BRIE, and a known/chosen-plaintext attack can break BRIE with only one known/chosen plain-image. Experiments are made to verify the defects of BRIE and the feasibility of the attack.

/pdf/on-the-security-of-an-image-encryption-method-2ygpbrmqus.pdf

Xuan Zheng

Papers

Cryptanalysis of a chaotic image encryption method

Chaos-Based Encryption for Digital Images and Videos

Chaotic encryption scheme for real-time digital video

On the security of an image encryption method