K. M. S. Soyjaudah

Analytical Comparison of Cryptographic Techniques for Resource-Constrained Wireless Security

With the widespread growth in applications for resource-limited Wireless Sensor Networks (WSN), the need for reliable and efficient security mechanisms for them has increased manifold but its implementation is a non-trivial task. Limitations in processing speed, battery power, bandwidth and memory constrain the applicability of existing cryptography Algorithms for WSNs. In this paper, two potential block ciphers, namely the RC5 and AES-Rijndael, are analyzed and their suitability for resourcelimited wireless network security are compared based on performance criteria such as computational complexity overhead and energy consumption. Using simulation tests and analytical models, we provide important analysis and considerations on practical feasibility of these cryptographic Algorithms in sensor networks to help designers predict security performance under a set of constraints for WSNs.

Energy consumption and computational analysis of rijndael-AES

Encryption, which is the backbone of security protocols, is computationally intensive and consumes energy and computational resources that are limited in wireless devices. This paper focuses on evaluating the performance of Rijndael-Advanced Encryption Standard (AES) encryption scheme in terms of energy consumed and execution time, and modeling the computational operations involved. The objective is to provide simulation results to help in the design and optimization of efficient cryptographic techniques. The computational model as a function of primitive operations shows a good estimate of encryption complexity, hence the energy consumption for encryption.

Comparative Study of Path Loss Using Existing Models for Digital Television Broadcasting for Summer Season in the North of Mauritius

Field strength, carrier-to-noise ratio and bit-error- rate were measured at two antenna heights (4 m and 6 m) in the north of Mauritius Island following the launching of digital broadcasting in October 2005 at UHF Bands (470 to 862 MHz). Results show that the path loss is not constant at various locations for a constant distance around the base station. This shows the irregularity of the terrain. Furthermore, it is observed that for a particular location, the path loss for an antenna height of 6 m is lower than that of 4 m. This justifies the presence of multipath effects and the deviation of the results from the expected values. This means that the probability of signal errors is less at an antenna height of 6 m than that of 4 m. The calculated path loss is compared with other existing propagation models such as free- space, Lee, Hata and extended COST-231. The results show that Hata model is closer to the calculated path loss, that is, better agreement in sub-urban area.

Investigating performance of neural networks in authentication using keystroke dynamics

Biometrics technology has emerged as the desired solution for a range of secure applications where a persons identity must be determined. Biometrics is currently controlling network and physical access in numerous high risk areas, including airport customs and immigration desks, financial malls among others. This paper compares applications of neural networks to the field of hardened password mechanism in a typical workplace environment.

Path loss analysis between the north and the south of mauritius with some existing models for digital television broadcasting for summer season at UHF bands

After the official launching in October 2005 of digital terrestrial television (DTT), plans were made to carry out field measurements across the island. Field strength, carrier-to-noise ratio and bit-error-rate were measured at two antenna heights (4 m and 6 m) both in the north and south of Mauritius at UHF bands (470 to 862 MHz). In this paper, we compare the measured path loss obtained for the sub-urban northern area with that for the rural southern area and then with four propagation models, that is, free-space, Lee, Hata and extended COST-231. Firstly, for both areas, the results show that the path loss is not constant at various locations for a constant distance around the respective base station showing that the terrain of Mauritius is irregular. Moreover, for the same antenna height, the path loss is higher in the south than in the north by 5 dB to 20 dB depending upon the distance from the station. The effects of the slow fading effect (shadow) and fast fading effect are more pronounced in the south than in the north, causing higher probability of signal errors. Secondly, we found that Lee and free space models are not in agreement with the values obtained for both regions. However, observations show that Hata and extended COST 231 models give better agreement and hence, can be used to model areas in Mauritius.

Speed sensorless control of a converter-fed DC motor

This paper presents a speed sensorless control scheme for a DC motor driven by a DC-DC converter. The proposed system is based on the computation of the motor speed from the converter output line parameters. The performance of the designed system is also evaluated.

Design and implementation of Rijndael algorithm for GSM encryption

Encryption is used in communications systems to protect information being transmitted over a channel from being intercepted and read by unauthorised parties. This protection is achieved by converting the original message (plain text) into an encoded form (cipher text) that appears to be a random stream of symbols. A5 is the encryption algorithm used in order to ensure privacy of conversations on GSM mobile phones. Two versions of the stream cipher are available. The strong version, A5/1, is used in most countries while the weaker A5/2 is used in countries on which export restrictions apply. In the third quarter of 2002, ETSI published GSMs new security algorithm, known as A5/3. A5/3 is based on the Kasumi algorithm, specified by 3GPP for use in 3G mobile systems. In this same period the Rijndael algorithm was being discussed in the cryptographic community for its use in mobile security. In this work it will be shown that a modified A5/3 based on Rijndael provides a higher level of security than A5/1 and even the original A5/3.

A comparative study of secret code variants in terms of keystroke dynamics

The rise of the Internet and the push for ubiquitous computing has brought a proliferation of numerous single method solutions, forcing users to remember numerous secret codes, a task that is becoming increasingly difficult. On the web, codes are used by publications, blogs, Webmail, e-commerce sites, and financial institutions. Elsewhere, they serve as authentication mechanism for Internet service providers (ISPs), email servers, local and remote host account, ATM, voicemails and so on. Existing textual passwords, token based systems, and other methods often do not offer the necessary security standard. Fortunately biometric systems that are based on the biological features of the user when typing texts are very promising in enhancing the de facto textual password. The main objective of this paper is to assess and report on the suitability of keystroke dynamics in protecting access to resources when users are typing the different types of password that exist.

Performance of joint source–channel decoding with iterative bit combining and detection

A joint source–channel decoding scheme (JSCD) with iterative bit combining (IBC) is proposed, which exploits two types of a priori information. The first one is the a priori bit probabilities obtained from source statistics, and the second is the channel a priori probabilities obtained from saved extrinsic information of previous transmissions. The JSCD-IBC scheme also incorporates iterative detection as both a stopping criteria and mechanism for triggering retransmissions. This adds an implicit adaptivity to the system and prevents excess iterations/retransmissions from being effected. The performance of the JSCD-IBC scheme is evaluated with four different iterative detection schemes and also two different types of variable length codes, Huffman and reversible variable length codes. Simulation results show that a significant performance gain in terms of bit error rate, throughput, and number of iterations can be achieved with the JSCD-IBC scheme as compared to a separate decoding scheme.

Combined Huffman code and modified generalised array codes: Concatenated form without feedback

In this paper, a combined technique to reduce redundancy and provide error control is presented. The proposed technique involves the concatenation of Huffman code and Modified Generalised Array Code. It is shown that this scheme gives a reduction in overall complexity without loss of error performance as compared to that employing a trellis decoder of GAC code followed by a Huffman decoder. An algorithm for the design of a combined trellis code is proposed. The proposed design is implemented in software and its error performances are compared with those of the separate Huffman and Modified Generalised Array Codes as well as the uncoded schemes. Furthermore, a comparative complexity study in terms of the total number of states and computations is carried for the combined and separate schemes. This proposed combined code is suitable for both information storage devices and data transmission.