Dynamic block encryption with self-authenticating key exchange

One of the greatest challenges facing cryptographers is the mechanism used for key exchange. When secret data is transmitted, the chances are that there may be an attacker who will try to intercept and decrypt the message. Having done so, he/she might just gain advantage over the information obtained, or attempt to tamper with the message, and thus, misguiding the recipient. Both cases are equally fatal and may cause great harm as a consequence. In cryptography, there are two commonly used methods of exchanging secret keys between parties. In the first method, symmetric cryptography, the key is sent in advance, over some secure channel, which only the intended recipient can read. The second method of key sharing is by using a public key exchange method, where each party has a private and public key, a public key is shared and a private key is kept locally. In both cases, keys are exchanged between two parties. In this thesis, we propose a method whereby the risk of exchanging keys is minimised. The key is embedded in the encrypted text using a process that we call `chirp coding', and recovered by the recipient using a process that is based on correlation. The `chirp coding parameters' are exchanged between users by employing a USB flash memory retained by each user. If the keys are compromised they are still not usable because an attacker can only have access to part of the key. Alternatively, the software can be configured to operate in a one time parameter mode, in this mode, the parameters are agreed upon in advance. There is no parameter exchange during file transmission, except, of course, the key embedded in ciphertext. The thesis also introduces a method of encryption which utilises dynamic blocks, where the block size is different for each block. Prime numbers are used to drive two random number generators: a Linear Congruential Generator (LCG) which takes in the seed and initialises the system and a Blum-Blum Shum (BBS) generator which is used to generate random streams to encrypt messages, images or video clips for example. In each case, the key created is text dependent and therefore will change as each message is sent. The scheme presented in this research is composed of five basic modules. The first module is the key generation module, where the key to be generated is message dependent. The second module, encryption module, performs data encryption. The third module, key exchange module, embeds the key into the encrypted text. Once this is done, the message is transmitted and the recipient uses the key extraction module to retrieve the key and finally the decryption module is executed to decrypt the message and authenticate it. In addition, the message may be compressed before encryption and decompressed by the recipient after decryption using standard compression tools

Entropy in Dynamic Systems

In order to measure and quantify the complex behavior of real-world systems, either novel mathematical approaches or modifications of classical ones are required to precisely predict, monitor, and control complicated chaotic and stochastic processes. Though the term of entropy comes from Greek and emphasizes its analogy to energy, today, it has wandered to different branches of pure and applied sciences and is understood in a rather rough way, with emphasis placed on the transition from regular to chaotic states, stochastic and deterministic disorder, and uniform and non-uniform distribution or decay of diversity. This collection of papers addresses the notion of entropy in a very broad sense. The presented manuscripts follow from different branches of mathematical/physical sciences, natural/social sciences, and engineering-oriented sciences with emphasis placed on the complexity of dynamical systems. Topics like timing chaos and spatiotemporal chaos, bifurcation, synchronization and anti-synchronization, stability, lumped mass and continuous mechanical systems modeling, novel nonlinear phenomena, and resonances are discussed

Research on digital image watermark encryption based on hyperchaos

The digital watermarking technique embeds meaningful information into one or more watermark images hidden in one image, in which it is known as a secret carrier. It is difficult for a hacker to extract or remove any hidden watermark from an image, and especially to crack so called digital watermark. The combination of digital watermarking technique and traditional image encryption technique is able to greatly improve anti-hacking capability, which suggests it is a good method for keeping the integrity of the original image. The research works contained in this thesis include: (1)A literature review the hyperchaotic watermarking technique is relatively more advantageous, and becomes the main subject in this programme. (2)The theoretical foundation of watermarking technologies, including the human visual system (HVS), the colour space transform, discrete wavelet transform (DWT), the main watermark embedding algorithms, and the mainstream methods for improving watermark robustness and for evaluating watermark embedding performance. (3) The devised hyperchaotic scrambling technique it has been applied to colour image watermark that helps to improve the image encryption and anti-cracking capabilities. The experiments in this research prove the robustness and some other advantages of the invented technique. This thesis focuses on combining the chaotic scrambling and wavelet watermark embedding to achieve a hyperchaotic digital watermark to encrypt digital products, with the human visual system (HVS) and other factors taken into account. This research is of significant importance and has industrial application value

A competitive study of cryptography techniques over block cipher

The complexity of cryptography does not allow many people to actually understand the motivations and therefore available for practicing security cryptography. Cryptography process seeks to distribute an estimation of basic cryptographic primitives across a number of confluences in order to reduce security assumptions on individual nodes, which establish a level of fault-tolerance opposing to the node alteration. In a progressively networked and distributed communications environment, there are more and more useful situations where the ability to distribute a computation between a number of unlike network intersections is needed. The reason back to the efficiency (separate nodes perform distinct tasks), fault-tolerance (if some nodes are unavailable then others can perform the task) and security (the trust required to perform the task is shared between nodes) that order differently. Hence, this paper aims to describe and review the different research that has done toward text encryption and description in the block cipher. Moreover, this paper suggests a cryptography model in the block cipher

Digital watermarking methods for data security and authentication

Philosophiae Doctor - PhDCryptology is the study of systems that typically originate from a consideration of the ideal circumstances under which secure information exchange is to take place. It involves the study of cryptographic and other processes that might be introduced for breaking the output of such systems - cryptanalysis. This includes the introduction of formal mathematical methods for the design of a cryptosystem and for estimating its theoretical level of securit

Image Cryptography using Parameterized Multiband Eigen Wavelet Filterbank

In this paper, we present an eigen filterbank based approach for image cryptography. The proposed method consists of designing a wavelet filterbank using eigenfilter based approach and use the designed filterbank for image encryption with new methodology. We have extended an eigenfilter based approach for the design of multiband two-channel filter bank. This method is based on designing multiband analysis filter, followed by the design of complementary multiband synthesis filter. The designed filterbank has various user defined parameters (key) like, number of bands in the filter spectrum, cutoff frequency of individual frequency band and the level of decomposition. Based on the selection of these parameters we can design a unique filterbank, which can be used for the image encryption. At the decryption end, the original image can be reconstructed only if user selected parameters are known. We present few design examples for the illustration purpose. We also give detail of complexity analysis of the entire cryptography system and also present the time analysis. The proposed approach provides more number of user parameters as compared to state-of-art methods, which can be used as more secure key. It is also observed that the computation time of the proposed approach is comparable

Image Encryption Using Huffman Coding for Steganography, Elliptic Curve Cryptography and DWT for Compression

Abstract-An abstract is a brief summary of a research article or in-depth analysis of a particular subject or discipline, and is often used to help the reader quickly ascertain the paper's purpose. Images can be encrypted in several ways, by using different techniques and different encryption methods. In this paper, I am using Huffman Coding method for image steganography, Elliptic Curve Cryptography for image encryption and Discrete Wavelet Transform for image compression. In my work I am using steganography, encryption and compression all together on the image data. After applying all these techniques on image data it results in an encryption method which is highly secure. For the implementation of the proposed work we are using Matlab software

Entropy in Image Analysis II

Image analysis is a fundamental task for any application where extracting information from images is required. The analysis requires highly sophisticated numerical and analytical methods, particularly for those applications in medicine, security, and other fields where the results of the processing consist of data of vital importance. This fact is evident from all the articles composing the Special Issue "Entropy in Image Analysis II", in which the authors used widely tested methods to verify their results. In the process of reading the present volume, the reader will appreciate the richness of their methods and applications, in particular for medical imaging and image security, and a remarkable cross-fertilization among the proposed research areas

New Stenographic method to hiding information in digital image

Steganography is the art of hiding information in different cover media, then sending & displaying the hidden information especially in public places, Therefore, different methods have been proposed so far for hiding information. In this paper new method was proposed called keyboard method because it works in manner like the keyboard. It is insure that no change on image which must send to another side