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」

This chapter introduces the subject of statistical pattern recognition (SPR). It starts by considering how features are defined and emphasizes that the nearest neighbor algorithm achieves error rates comparable with those of an ideal Bayes’ classifier. The concepts of an optimal number of features, representativeness of the training data, and the need to avoid overfitting to the training data are stressed. The chapter shows that methods such as the support vector machine and artificial neural networks are subject to these same training limitations, although each has its advantages. For neural networks, the multilayer perceptron architecture and back-propagation algorithm are described. The chapter distinguishes between supervised and unsupervised learning, demonstrating the advantages of the latter and showing how methods such as clustering and principal components analysis fit into the SPR framework. The chapter also defines the receiver operating characteristic, which allows an optimum balance between false positives and false negatives to be achieved.

Statistical Pattern Recognition

Quantum steganography is the technique which hides a secret message into quantum covers such as quantum images. In this paper, two blind LSB steganography algorithms in the form of quantum circuits are proposed based on the novel enhanced quantum representation (NEQR) for quantum images. One algorithm is plain LSB which uses the message bits to substitute for the pixels’ LSB directly. The other is block LSB which embeds a message bit into a number of pixels that belong to one image block. The extracting circuits can regain the secret message only according to the stego cover. Analysis and simulation-based experimental results demonstrate that the invisibility is good, and the balance between the capacity and the robustness can be adjusted according to the needs of applications.

LSB Based Quantum Image Steganography Algorithm

An overview of encryption algorithms in color images

Color image compression and encryption scheme based on compressive sensing and double random encryption strategy

Steganalysis is the art of detecting the message's existence and blockading the covert communication. Various steganography techniques have been proposed in literature. The Least Significant Bit (LSB) steganography is one such technique in which least significant bit of the image is replaced with data bit. As this method is vulnerable to steganalysis so as to make it more secure we encrypt the raw data before embedding it in the image. Though the encryption process increases the time complexity, but at the same time provides higher security also. This paper uses two popular techniques Rivest, Shamir, Adleman (RSA) algorithm and Diffie Hellman algorithm to encrypt the data. The result shows that the use of encryption in Steganalysis does not affect the time complexity if Diffie Hellman algorithm is used in stead of RSA algorithm.

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Information Hiding Using Least Significant Bit Steganography and Cryptography

Security of data/images is one of the crucial aspects in the gigantic and still expanding domain of digital transfer. Encryption of images is one of the well known mechanisms to preserve confidentiality of images over a reliable unrestricted public media. This medium is vulnerable to attacks and hence efficient encryption algorithms are necessity for secure data transfer. Various techniques have been proposed in literature till date, each have an edge over the other, to catch-up to the ever growing need of security. This paper is an effort to compare the most popular techniques available on the basis of various performance metrics like differential, statistical and quantitative attacks analysis. To measure the efficacy, all the modern and grown-up techniques are implemented in MATLAB-2015. The results show that the chaotic schemes used in the study provide highly scrambled encrypted images having uniform histogram distribution. In addition, the encrypted images provided very less degree of correlation coefficient values in horizontal, vertical and diagonal directions, proving their resistance against statistical attacks. In addition, these schemes are able to resist differential attacks as these showed a high sensitivity for the initial conditions, i.e. pixel and key values. Finally, the schemes provide a large key spacing, hence can resist the brute force attacks, and provided a very less computational time for image encryption/decryption in comparison to other schemes available in literature.

A Survey of Image Encryption Algorithms

Confidentiality of images during data communication is a prime concern of many researchers, as a result, several mechanisms have been proposed for image encryption. An encryption for image is said to be effective if it has large key space, aperiodic nature and sensitive to the initial conditions. In addition, it is also desired that the mechanism must have a good combination of computational speed, security and time complexity. These features can be induced in the encryption schemes by incorporation of chaos during encryption/decryption process. In this paper, a novel image encryption scheme based on chaotic maps and Vigenere Scheme is proposed. This scheme has one round consisting of two steps: diffusion and confusion. The former step involves three stages: forward diffusion, matching process using Vigenere scheme and backward diffusion. In later part, position permutation using chaotic map is used to swap pixel positions. The proposed as well as other mechanisms in literature are implemented in Matlab-2015 and their efficacy are compared using several performance metrics. The simulation results show that our scheme is better in terms of time complexity while keeping Peak Signal to Noise Ratio (PSNR) values same and having almost ideal entropy, Number of Pixels Change Rate (NPCR) and Unified Average Changing Intensity (UACI).

An innovative image encryption scheme based on chaotic map and Vigenère scheme

The growth of portable wireless communication devices has pushed designers to design miniature size antennas. The most prized among miniature antenna choices is the micro-strip patch antenna. These antennas have significant advantages such as low profile, light weight, relatively low manufacturing cost, and polarization diversity. This paper compares the performance of micro-strip patch antenna having different shapes of the patch (Square, Elliptical, Annular ring, Triangular) at a frequency of 2.43 GHz. To compare and analyze the performance, High Frequency Structure Simulator (HFSS) software was used. The results show that the size of the antenna will be smallest in case of square shape patch antenna followed by elliptical, triangular and annular ring. These results can be very useful while designing microstrip patch antenna.

Performance Comparison of Micro-strip Antennas with Different Shape of the Patch

Advancement in digital technologies has resulted in increased data transfer over internet in recent years. As a result, security of images/data is one of the biggest concern of many researchers. Therefore several cryptographic schemes have been proposed for image/data encryption. An efficient cryptographic scheme is one that have high brute force search time, low execution time complexity and should be able to provide good security. In this paper, several ciphers (traditional as well as modern) for images are compared based on various parameters such as: Time complexity, Peak Signal to Noise Ratio (PSNR), Number of Pixels Change Rate (NPCR), Unified Average Changing Intensity (UACI) and Entropy. In addition, the paper also shows the shortcomings of traditional ciphers that were used for text and how modern ciphers overcome this limitations. The analysis of simulation result shows that chaotic encryption schemes are most efficient and better than others.

Shailender Gupta

Papers

Information Hiding Using Least Significant Bit Steganography and Cryptography

A Survey of Image Encryption Algorithms

An innovative image encryption scheme based on chaotic map and Vigenère scheme

Performance Comparison of Micro-strip Antennas with Different Shape of the Patch

Image Encryption Schemes : A Complete Survey