Manas Kumar Haldar

Secure electronic voting system based on image steganography

As information technology evolves over time, the need for a better, faster, more convenient and secure electronic voting is relevant since the traditional election procedures cannot satisfy all of voters demands. To increase the number of voters and to offer an enhanced procedure in an election, many researchers have been introducing novel and advanced approaches to secure electronic voting systems. This paper proposes a secure electronic voting system that provides enhanced security by implementing cryptography and steganography in Java. As a preliminary investigation, two steganography techniques are considered and their performances are compared for different image file formats.

A novel compact quadruple-mode microstrip bandpass filter with low harmonic response

A novel compact quadruple-mode resonator is presented in this paper. The quadruple-mode resonator consists of a pair of quarter-wavelength resonators and a pair of L-C type resonators connected to each other through a grounded via. The new resonator has the same size as a dual mode square open-loop resonator published earlier, but has four modes and better harmonic response. The resonator filter has a centre frequency of 0.99 GHz and passband insertion loss of 1.2 dB. The selectivity of the filter and stopband response can be improved by implementing different feed structures. Simulated and measured results are in good agreement.

An Aperture-Backed H-Ring Ultra-Wideband Bandpass Filter with Floating Conductor for Spurious Suppression

Abstract This article presents analyses of and design procedures for a compact quintuple-resonance aperture-backed ultra-wideband bandpass filter. First, a one-wavelength H-ring resonated at 6.85-GHz center frequency is coupled with open stubs at both sides to produce a triple-resonance filter characteristic. To increase the resonances of the filter to five, stepped-impedance feed lines are then implemented to introduce two extra transmission poles at each side of the center frequency. The filter, which has a structure that is both horizontally and vertically symmetrical, simplifies the analysis to a quarter of the structure while enabling the stepped-impedance feed lines to be designed analytically. A wide aperture is then etched on the ground plane directly below each interdigital line to achieve strong coupling. This results in wider coupling gaps to enable in-house fabrication. A floating strip conductor is then added at the center of each ground aperture to suppress the spurious harmonic appearing at twice the fundamental frequency of the ring resonator. The filter is fabricated on an RT/Duroid 6010.2LM substrate (Rogers Corporation, Rogers, Connecticut, USA). The simulated and measured responses are in good agreement.

Compact microstrip bandpass filters using triple-mode resonator

Step-by-step procedures for designing a third order bandpass filter and a sixth order bandpass filter using a triple-mode resonator are described in this paper. The triple-mode resonator is a square open-loop resonator with an open circuited stepped-impedance stub and a grounding via located at the symmetrical plane of the resonator. The equations for approximating the resonant frequencies of the resonator are obtained from odd and even mode analysis. To design a filter, first, the theoretical resonant frequencies for the filter are calculated. Then the basic dimensions of the resonator are approximated using the equations. The filter layouts are fine-tuned by simulation and verified by experiment to conclude the paper. The first spurious response occurs at about 3 times the center frequency of the first passband in both filters. The simulated and measured results are in good agreement.

A Modified Hair-Pin Resonator for the Design of Compact Bandpass Filter with Suppression of Even Harmonics

A new design consideration is explored for a hair-pin resonator. A grounding via at the mid-point of the resonator acts as a perturbation to split the resonant frequencies. The via also suppresses even harmonics of the fundamental. The principle operation of the hair-pin resonator with a via is analyzed and verified by measurement. It is shown that such a hair-pin resonator can be made more compact using stepped impedance line. A compact 4-pole bandpass filter using the modified compact hair-pin resonator with a via is demonstrated. Simulation and measured results showed good agreement.

Analysis of image steganography techniques in secure online voting

As the demand of more secure yet efficient image steganography tools has increased, different steganography approaches have been proposed. In this paper some of those approaches are examined in order to identify the appropriate image steganography technique to be implemented in an electronic voting system. Different set of criteria has been set into place to analyze and evaluate the strengths and weaknesses of the presented steganography approaches.

Circuit modeling for the design of Composite Right/Left-handed ring resonator

A desirable feature of a Composite Right/Left-handed (CRLH) dual-mode ring resonator is the suppression of the second harmonic. This paper presents the results of an investigation of the CRLH dual-mode ring resonator filter by using circuit modeling approach. The circuit approach shows that one can use a single capacitor unlike three capacitors in previous design. It also provides an initial design which can then be fine tuned by simulation. A fourth order Chebyshev filter is then implemented using two CRLH dual-mode ring resonators. The design and implementation agree reasonably well.

Vulnerability Studies of E2E Voting Systems

In the recent years, the existence of end-to-end voter-verifiable (E2E) voting system had increased significantly. Some of the prospective ones have been used in a medium to large scale elections. We have also developed one (eVote). In this paper we review their capabilities to provide an individual and universally verifiable voting system, incoercibility and receipt-freeness to ensure election integrity. We compare some properties along with its resistance against malicious attacks.

An aperture-backed sextuple-mode ultra-wideband bandpass filter

In this paper, a sextuple-mode ring resonator ultra-wideband bandpass filter is presented. The objective is to enhance the selectivity of a quintuple-mode filter by introducing an additional transmission pole within the passband. The extra pole comes from two open stubs inserted symmetrically inside the ring resonator. Analysis of the filter is done to show the relationship between the six resonant frequencies, and characteristic impedance and electrical length of the stubs. The filter is designed, fabricated and measured. The measured responses are in good agreement with simulations. The filter exhibits 108.02% 3dB fractional bandwidth at 6.85GHz centre frequency.

Harmonic, Intermodulation and Cross-Modulation Distortion in Directly Modulated Quantum Cascade Lasers

Using a simplified rate equation model, expressions for harmonic, intermodulation and cross-modulation distortion for a directly modulated quantum cascade laser can be derived. This paper shows how such derivations can be done and discusses some implications for quantum cascade lasers. It is important to understand such distortion, especially for applcations in communication systems.