96,751 research outputs found

    Modelling and simulation of a biometric identity-based cryptography

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    Government information is a vital asset that must be kept in a trusted environment and efficiently managed by authorised parties. Even though e-Government provides a number of advantages, it also introduces a range of new security risks. Sharing confidential and top-secret information in a secure manner among government sectors tend to be the main element that government agencies look for. Thus, developing an effective methodology is essential and it is a key factor for e-Government success. The proposed e-Government scheme in this paper is a combination of identity-based encryption and biometric technology. This new scheme can effectively improve the security in authentication systems, which provides a reliable identity with a high degree of assurance. In addition, this paper demonstrates the feasibility of using Finite-state machines as a formal method to analyse the proposed protocols

    Influences of magnetic coupling process on the spectrum of a disk covered by the corona

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    Recently, much attention has been paid to the magnetic coupling (MC) process, which is supported by very high emissivity indexes observed in Seyfert 1 galaxy MCG-6-30-15 and GBHC XTE J1650-500. But the rotational energy transferred from a black hole is simply assumed to be radiated away from the surrounding accretion disk in black-body spectrum, which is obviously not consistent with the observed hard power-law X-ray spectra. We intend to introduce corona into the MC model to make it more compatible with the observations. We describe the model and the procedure of a simplified Monte Carlo simulation, compare the output spectra in the cases with and without the MC effects, and discuss the influences of three parameters involved in the MC process on the output spectra. It is shown that the MC process augments radiation fluxes in the UV or X-ray band. The emergent spectrum is affected by the BH spin and magnetic field strength at the BH horizon, while it is almost unaffected by the radial profile of the magnetic field at the disk. Introducing corona into the MC model will improve the fitting of the output spectra from AGNs and GBHCs.Comment: 15 pages, 5 figures, accepted by A&

    Analysis of security protocols using finite-state machines

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    This paper demonstrates a comprehensive analysis method using formal methods such as finite-state machine. First, we describe the modified version of our new protocol and briefly explain the encrypt-then-authenticate mechanism, which is regarded as more a secure mechanism than the one used in our protocol. Then, we use a finite-state verification to study the behaviour of each machine created for each phase of the protocol and examine their behaviour s together. Modelling with finite-state machines shows that the modified protocol can function correctly and behave properly even with invalid input or time delay

    Biometric identity-based cryptography for e-Government environment

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    Government information is a vital asset that must be kept in a trusted environment and efficiently managed by authorised parties. Even though e-Government provides a number of advantages, it also introduces a range of new security risks. Sharing confidential and top-secret information in a secure manner among government sectors tend to be the main element that government agencies look for. Thus, developing an effective methodology is essential and it is a key factor for e-Government success. The proposed e-Government scheme in this paper is a combination of identity-based encryption and biometric technology. This new scheme can effectively improve the security in authentication systems, which provides a reliable identity with a high degree of assurance. In addition, this paper demonstrates the feasibility of using Finite-state machines as a formal method to analyse the proposed protocols

    Realistic Gluino Axion Model Consistent with Supersymmetry Breaking at the TeV Scale

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    The recently proposed model of using the dynamical phase of the gluino to solve the strong CP problem is shown to admit a specific realization in terms of fundamental singlet superfields, such that the breaking of supersymmetry occurs only at the TeV scale, despite the large axion scale of 10^{9} to 10^{12} GeV. Phenomenological implications are discussed.Comment: 12 pp, 2 fig

    Actions for Vacuum Einstein's Equation with a Killing Symmetry

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    In a space-time MM with a Killing vector field ξa\xi^a which is either everywhere timelike or everywhere spacelike, the collection of all trajectories of ξa\xi^a gives a 3-dimension space SS. Besides the symmetry-reduced action from that of Einstein-Hilbert, an alternative action of the fields on SS is also proposed, which gives the same fields equations as those reduced from the vacuum Einstein equation on MM.Comment: 8 pages, the difference between the action we proposed and the symmetry-reduced action is clarifie
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