Rupak Kharel

Indirect coupled oscillators for keystream generation in secure chaotic communication

In this paper, we propose a secure communication system composed of four chaotic oscillators. Two of those oscillators are unidirectionally coupled and employed as transmitter and receiver. The other two oscillators are indirectly coupled and are employed as keystream generators. The novelty lies in the generation of the same chaotic key both in the transmitter and receiver side for encryption and decryption purposes. We show, in particular, that it is possible to synchronize the two keystream generators even though they are not directly coupled. So doing, an estimation of the keystream is obtained allowing decrypting the message. The performance of the proposed communication scheme is shown via simulation using Chua and the Lorenz oscillators.

Secure digital communication using discrete-time chaotic systems via indirect coupling synchronization

In this work, the synchronization of two indirectly coupled discrete-time chaotic systems is first demonstrated. Next, the result is then applied for presenting a secure communication system. The novelty of the proposed method lies on the generation of encryption key stream for discrete-time chaotic systems using indirect coupled synchronization. Simulation is performed for the proposed synchronization and communication system and it is shown that the message can be successfully recovered. Moreover, security analysis of the proposed method is also carried out to show that the technique is indeed potentially secure.

Chaotic bidirectional communication using high gain observers with modified inclusion method

This work is concerned with the design of a chaotic communication system based on a modified inclusion method. For this, we propose a bidirectional transmitter-receiver communication scheme whereby the transmitter is a Rossler oscillator and the receiver is a corresponding nonlinear high gain observer. The main motivation to employ a bidirectional communication scheme is exclusively to eliminate the nonlinearities in the error dynamics of the observer. We propose an approach where a message is embedded with a proportional and integrated form in the state variables, proving that if amplification factors are correctly calculated the transfer function is equal to unity and message recovery is possible with simple error dynamics subtraction. Consequently the proposed technique does not require a left inversion message recovery block, contrary to traditional inclusion methodology.

A novel chaotic encryption technique for secure communication

Abstract In this work, a novel chaotic encryption technique is proposed to realize a secure communication system. In the proposed method, the message signal to be transmitted is first encrypted using a chaotic keystream and then modulated with a chaotic signal. At the receiver end, the received chaotic signal is used for synchronization and to recover the encrypted signal. After applying the same keystream used in transmitter side, the message signal could be decrypted back. The main contribution of this work is generation of the keystream which is not part of the transmitter chaotic oscillator but is produced using an oscillator of a different structure.

A new chaos-based communication scheme using observers

In this paper, we propose a new chaos-based communication scheme using observers. The novelty lies in the masking procedure that is employed to hide the confidential information using the chaotic oscillator. We use a combination of the so-called addition and inclusion methods to mask the information. We compare two observers, the proportional observer (P-observer) and the proportional integral observer (PI-observer) that are employed as receivers for the proposed communication scheme. We show that the P-observer is not suitable for the proposed communication scheme since it imposes unpractical constraints on the messages to be sent. On the other hand, we show that the PI-observer is the best solution for the proposed communication scheme since it allows greater flexibility in choosing the gains of the observer and it does not impose any unpractical restriction on the message.

Digitization of chaotic signal for reliable communication in non-ideal channels

A new method of chaotic communication system based on digitization of the chaotic signal is proposed. The digitally encoded chaotic signal is transmitted through a practical channel and recovered at the receiver. Simulation results show that despite being errors in the received bit sequence, the observer is able to synchronise and recover message signal with high accuracy provided bit error rate is < 10-4. The proposed method is compatible with the existing digital communication system and hence could be implemented in real scenario with no or little modification in the existing infrastructure.

Performance evaluation of free space optical communication under the weak turbulence regime

This paper experimentally investigates the performance of an FSO communications system by increasing the link length under an indoor laboratory controlled turbulence condition. A plane mirror is used to increase the link length by means of optical beam reflection. The experimental results show that the turbulence strength is highly dependent on the link length. The measured scintillation index (SI) for a link of 6 meters long with no reflection is 0.043, which increases to 0.56 with reflection for a link of 12 meters. Furthermore, the Q-factor is measured as a performance metric for the FSO link with and without the reflected beams for different SI values. The results show that the performance of the FSO link with reflection deteriorates very rapidly with the Q-factor being halved compared at SI of 0.01.

Observer-based secure communication using indirect coupled synchronization

In this paper, an observer-based secure communication system composed of four chaotic oscillators is proposed. Observer based synchronization is achieved between two of these oscillators and employed as a transmitter and a receiver. The other two oscillators are indirectly coupled and are employed as keystream generators. The novelty lies in the generation of the same chaotic keystream both in the transmitter and receiver side for encryption and decryption purposes. We show, in particular, that it is possible to synchronize the two keystream generators even though they are not directly coupled. So doing, an estimation of the keystream is obtained allowing decrypting the message. The performance of the proposed communication scheme is shown via simulation using the Chua and Lorenz oscillators.

Modified chaotic shift keying using indirect coupled chaotic synchronization for secure digital communication

In this paper, a modified chaotic shift keying method is proposed to transmit digital bits securely over a communication channel. The scheme is based upon encrypting the digital bits 0 and 1 into infinite levels by applying the keystream such that there is no recognisable pattern in the encoded transmitted signal. The encoded transmitting signal generated is shown to resist popular attack method therefore realizing a secure and trustworthy digital communication system. Keywords: Chaotic synchronization, Chaotic shift keying, Secure Communication, Return Maps, Encryption, Chaotic simulation.

Smart street lighting over narrowband PLC in a smart city: The Triangulum case study

As municipalities continue to embrace digital revolution in a bid to become smarter cities, the unique intersection between ICT and development road map is inspiring new innovative applications. While this quest for smart city continues, the transformation of street lighting has become a topical issue. As part of ongoing investigation in Triangulum smart city project, this paper presents some simulation results on the use of narrowband powerline communication (NPLC) for street lights monitoring and control. The results show that, with low power, NPLC can support a 3.5km network of street lights without using a relay. It is also shown that, when the data packet size quadruples, latency degrades by up to 22.63% (242.03ms) in the worst case.