Applications of tripled chaotic maps in cryptography

Security of information has become a major issue during the last decades. New algorithms based on chaotic maps were suggested for protection of different types of multimedia data, especially digital images and videos in this period. However, many of them fundamentally were flawed by a lack of robustness and security. For getting higher security and higher complexity, in the current paper, we introduce a new kind of symmetric key block cipher algorithm that is based on \emph{tripled chaotic maps}. In this algorithm, the utilization of two coupling parameters, as well as the increased complexity of the cryptosystem, make a contribution to the development of cryptosystem with higher security. In order to increase the security of the proposed algorithm, the size of key space and the computational complexity of the coupling parameters should be increased as well. Both the theoretical and experimental results state that the proposed algorithm has many capabilities such as acceptable speed and complexity in the algorithm due to the existence of two coupling parameter and high security. Note that the ciphertext has a flat distribution and has the same size as the plaintext. Therefore, it is suitable for practical use in secure communications.Comment: 21 pages, 10 figure

VoIP Speech Encryption System Using Stream Cipher with Chaotic Key Generator

Abstract— Recently, with the development multimedia technologies and wireless telecommunication, Voice over Internet Protocol, becomes widely used in communication between connecting people, VoIP allows people that are connected to the local network or the Internet to make voice calls using digital connection instead of based on the analog traditional telephone network. The technologies of Internet doesn’t give any security mechanism and there is no way to guarantee that the voice streams will be transmitted over Internet or network have not been intercepted in between. In this paper, VoIP is developed using stream cipher algorithm and the chaotic cryptography for key generator. It is based on the chaotic maps for generating a one-time random key used to encrypt each voice data in the RTP packet. Chaotic maps have been used successfully for encryption bulky data such as voice, image, and video, chaotic cryptography has good properties such as long periodicity, pseudo-randomness, and sensitivity to initial conditions and change in system parameters. A VoIP system was successfully implemented based on the on ITU-T G.729 for voice codec, as a multimedia encoding of Real-time Transport Protocol payload data, then, apply a proposed methods to generate three-mixed logistic chaotic maps [1] and then analysis the encryption/ decryption quality measures for speech signal based this method. The experimental work demonstrates that the proposed scheme can provide confidentiality to voice data with voice over IP performance quality, minimum lost in transmitted packet, minimum average delay, and minimum jitter. Keywords: VoIP; Speech encryption; logistic chaotic map; G.729; QoS; RT

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

Implementation of a Symmetric Chaotic Encryption Scheme

Voice over Internet Protocol technology (VoIP) is progressing commendably, but packet loss, propagation delay, jitter, unreliable IP networks, and vulnerability to attacks by Internet hackers are among critical issues that have been identified. Voice privacy and security needs to focused upon and data encryption techniques are the answers in providing the security needed. However, traditional cryptosystems demand high computational complexity andhigh digital signal processors which in return increases the cost of implementation. There is parallel growth in cryptographic techniques which originated anintense research activity and the search for new directions in cryptography such as chaotic encryption. Due to its deterministic nature and its sensitivity to initial conditions, chaos has a certain potential in creating a newway of securing information to be transmitted or stored. There are two main objectives to this project. First is study the feasibility of the chaotic encryption scheme in providing a solution in to preserve data security while maintaining the voice quality for voice over Internet Protocol. Secondly, a new scheme based on a chaos system will be implemented for voice data. In order to achieve the second objective, a study had been carried out on other proposed schemes mainly the Hierarchical Data Security Protection (HDSP) for VoIP. This scheme performs two main operations which is the data-frame interleaving and intra-frame data encryption using bit swapping. Based onthe HDSP scheme, the author suggests a new scheme using two level encryption techniques, based on chaos. In this scheme, the author uses the bit swapping technique as the second encryption-decryption level and enhances it with a first level encryption-decryption scheme using the two's compliment overflow nonlinearity encoder-decoder pair. The implementation ofthis scheme is specified to do real time processing ofvoice data. It can also be used to read, encrypt and write a wave file. The entire system is implemented, tested and validated using MATLAB and Visual C++. Due to the promising prospect ofchaotic encryption in the field ofcryptography, and the lack ofimplementation ofthis new encryption-decryption algorithm, this project focuses on introducing a new symmetric encryption-decryption scheme based on a chaos system for VoIP

A STUDY AND IMPLEMENTATION OF ENCRYPTION, WITH EMPHASIS ON CHAOTIC MAPS

The security of data transmitted over public communication networks and valuable data storage have necessitated the need for very secure cryptography. Applications like video teleconferencing, cable TV broadcast, etc use encryption extensively. Hence researches for better ways of protecting data are still underway. And this project was aimed at finding secure cipher by implementing Logistic Map Cipher for plaintext encryption and decryption. The research was based on both symmetric ciphers and asymmetric ciphers. The symmetric cryptosystem was chosenand finally implemented. In trying to implement logistic map, Chaotic Maps were briefly analyzed and other types of encryption were investigated in order to understand intensive and extensive applications of cryptography. The three main parts of focus are keys' generator, the encryption and decryption parts, which are the main steps before cryptanalysis can be carried out. In encryption, the individual success of different parts will guarantee a complete cipher

A Review of Analog Audio Scrambling Methods for Residual Intelligibility

In this paper, a review of the techniques available in different categories of audio scrambling schemes is done with respect to Residual Intelligibility. According to Shannon's secure communication theory, for the residual intelligibility to be zero the scrambled signal must represent a white signal. Thus the scrambling scheme that has zero residual intelligibility is said to be highly secure. Many analog audio scrambling algorithms that aim to achieve lower levels of residual intelligibility are available. In this paper a review of all the existing analog audio scrambling algorithms proposed so far and their properties and limitations has been presented. The aim of this paper is to provide an insight for evaluating various analog audio scrambling schemes available up-to-date. The review shows that the algorithms have their strengths and weaknesses and there is no algorithm that satisfies all the factors to the maximum extent. Keywords: residual Intelligibility, audio scrambling, speech scramblin