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Abstract: The self-shrinking generator SSG, an elegant keystream generator proposed by Meier and Staffelbach, is built up from a single n-stage primitive linear feedback shift register (LFSR) to produce a keystream of period , and linear complexity greater than half its period. In this article, we propose a new variant of the self-shrinking generator called the modified self-shrinking generator MSSG. This new generator is based on a primitive n-stage LFSR and uses an extended selection rule based on the XORed value of a pair of bits. We prove that the keystreams of the MSSG are balanced, and have period greater than or equal to , linear complexity greater than half the period, and possess good statistical properties. We investigate the security of the generator against various powerful cryptanalytic attacks. We show that the MSSG is more secure than the SSG against most of these attacks. Moreover, experiments show that for odd values of n, , the period of the keystreams generated by the MSSG attains its maximum value , and the linear complexity of these keystreams is very close to its upper bound. The NIST statistical test suite is applied to several thousands keystreams of the MSSG to demonstrate their good randomness properties. The obtained results show that keystreams of the MSSG have better randomness properties than those of the SSG. [ABSTRACT FROM AUTHOR]

This paper proposes a modification of the controlled chaotic Henon system suggested in [Li et al., 2004]. The dynamics of the proposed and existing 2-D systems are analyzed and new chaotic attractors are found in them. We show that these systems exhibit chaotic behavior for a wide range of control parameters. We also construct a chaotic modulation scheme with feedback based on a single controlled chaotic Henon system for use in cryptographic applications. The efficiency of this communication scheme is analyzed and is shown to provide a high level of security, resulting from the proper use of controllers. Furthermore, we propose a technique for generating random-like binary digits from the suggested controlled chaotic Henon systems. Unlike binary digits generated by chaotic Henon systems which usually do not possess random-like properties, the digits generated here are shown (numerically using the NIST statistical test suite) to possess excellent random-like properties. Furthermore, the generated bit sequences are demonstrated to have a large period, which may have useful applications in cryptography. [ABSTRACT FROM AUTHOR]

Abstract: Encryption in wireless communication systems is an extremely important factor to protect information and prevent fraud. In this paper, we propose a new encryption system for use in stream cipher applications. The design proposed is intended for hardware implementation and based on feedback shift registers interconnected in such a way that one register controls the clocking of the other n registers. The aim of this construction is to allow the production of a large family of distinct keystreams when the initial states and feedback functions of the feedback shift registers are unchanged. The produced keystreams are shown to possess the basic security requirements for cryptographic sequences such as long period, high linear complexity and good statistical properties, provided that suitable parameters are chosen. Furthermore, the design is shown to resist various types of cryptanalytic attacks. These characteristics and properties enhance its use as a suitable encryption system for stream cipher applications. [Copyright &y& Elsevier]

This paper proposes the construction of a new chaotic pseudorandom bit generator, which forms the main building block of a chaotic stream cipher. The design of the algorithm is based on a single chaotic map whose numerical orbit indirectly contributes towards the generation of the keystream. The latter is produced from the numerical orbit by applying a technique that searches for iterates in specific intervals [a,b], for some real numbers a and b, and outputs 0 or 1 based on the iterate preceding the targeted iterate. The generator suggested here is built up from a quadratic map. We analyze the cycle length of the keystreams and investigate the resistance of the generator to well-known cryptanalytic attacks. Furthermore, the statistic characteristics of the keystreams are examined numerically using the NIST statistical test suite. The numerical and theoretical results demonstrate that the proposed technique results in generating keystreams possessing very good cryptographic properties and high level of security against existing cryptanalytic attacks. Empirical results show that the search technique leads to the generation of keystreams possessing good randomness properties when applied to any chaotic map whose orbits have good randomness properties such as the quadratic map, tent map and sawtooth map. [ABSTRACT FROM AUTHOR]

This paper proposes a new technique for generating random-looking binary digits based on an irregularly decimated chaotic map. We present a class of irregularly decimated chaos-based keystream generators, related to the shrinking generator, for the generation of binary sequences. Each generator consists of two subsystems: a control subsystem and a generating subsystem, where each subsystem is based on a single chaotic map. This chaotic map is presented as a 1-D piecewise chaotic map related to the chaotic logistic map. We conduct an analysis of the dynamical behavior of the proposed map to integrate it as a component in the proposed generators subsystems. The output bits of these keystream generators are produced by applying a threshold function to convert the floating-point iterates of the irregularly decimated map into a binary form. The generated keystream bits are demonstrated to exhibit high level of security, long period length, high linear complexity measure and random-like properties at given certain parameter values. Standard statistical tests on the proposed generators, as well as other keystream generators, are performed and compared. [ABSTRACT FROM AUTHOR]

Abstract: The need for wireless communication systems has increased rapidly in the past few years and wireless communication has become more convenient in business and society. However, the air interface is vulnerable to eavesdropping, hence encryption in wireless communication systems is a necessity to keep sensitive information confidential and to prevent fraud. Furthermore, wireless devices such as Bluetooth devices and mobile phones require an encryption algorithm that is secure, fast and simple to implement. There are several cryptosystems for stream cipher applications such as A5/x used in GSM mobile communications. However, A5/x are vulnerable to cryptanalytic attacks. In this paper, a new clock-controlled cryptosystem intended for hardware implementation is proposed. The design has attractive properties such as simplicity and scalability. The cryptographical properties including period, balancedness, linear complexity and probability distribution are analyzed. The design provides the basic security requirements, and is resistant to known cryptanalytic attacks. It is shown that the irregular clocking introduced provides a certain level of strengthened security against several cryptanalytic attacks. These properties enhance its use as a suitable cryptosystem for stream cipher applications. [Copyright &y& Elsevier]