A novel mutual authentication scheme with minimum disclosure for rfid systems

In this paper we present a novel approach to authentication and privacy in RFID systems based on the minimum disclosure property and in conformance to EPC Class-1 Gen-2 specifications. We take into account the computational constraints of EPC Class-1 Gen-2 passive RFID tags and only the cyclic redundancy check (CRC) and pseudo random number generator (PRNG) functions that passive RFID tags are capable of are employed. Detailed security analysis of our scheme shows that it can offer robust security properties in terms of tag anonymity and tag untraceability while at the same time being robust to replay, tag impersonation and desynchronisation attacks. Simulations results are also presented to study the scalability of the proposed scheme and its impact on authentication delay.

Optimizing survey effort for burrow-nesting seabirds

Regular monitoring of seabird populations is necessary to improve our understanding of their responses to environmental change and inform conservation management. However, given the difficulty in accessing remote breeding sites and the limited resources typically available to land managers, conducting regular, extensive surveys of seabird populations is often not feasible. Our objective was to determine the minimum survey effort required to obtain accurate and precise population estimates of Short-tailed Shearwaters (Ardenna tenuirostris) and Little Penguins (Eudyptula minor), two abundant burrowing seabird species in southeastern Australia, by comparing bootstrapped means and confidence intervals under different sampling regimes on four islands. We found that, in many cases, survey effort (the proportion of transects and quadrats along transects surveyed) could be reduced. For Short-tailed Shearwaters, reducing the number of transects resulted in a maximum difference of 15% between the means at full survey effort and two levels of reduced survey effort. Means differed by <3% when we halved the number of quadrats. For Little Penguins, reducing the number of transects and quadrats by 50% resulted in differences of 7-40% and 4-34%, respectively, between the full and reduced survey effort means. Confidence intervals generally increased with decreasing survey effort for both species. Differences in required survey effort between the two species in our study may have been due to differences in burrow distribution on islands, with Short-tailed Shearwater burrows generally uniformly distributed on each island and Little Penguin burrows typically occurring in patches. These would be influenced by island-specific characteristics in concert with habitat preferences, population size, and seasonal variation in seabird abundance. Stratified sampling did not increase survey accuracy and simulations showed that large reductions in survey effort could be made under a pseudo-random sampling regime, with mean abundance estimates similar at most levels of survey effort. For both species, reducing the proportion of pseudo-random quadrats to 50% and 25% of the full survey effort produced confidence intervals of 12% and 21%, respectively, of the maximum, whereas a survey effort of 10% produced confidence intervals of up to 36% of the maximum for both species. A pseudo-random sampling regime would maximize survey efficiency because considerably fewer quadrats would be required and allow development of more efficient sampling protocols and regimes.

Offline grouping proof protocol for RFID systems

Several grouping proof protocols have been proposed over the years but they are either found to be vulnerable to certain attacks or do not comply with EPC Class-1 Gen-2 (C1G2) standard because they use hash functions or other complex encryption schemes. Also, synchronization of keys, forward security, proving simultaneity, creating dependence, detecting illegitimate tags, eliminating unwanted tag processing and denial-of-proof (DoP) attacks have not been fully addressed by many. Our protocol addresses these important gaps and is based on Quadratic Residues property where the tags are only required to use XOR, 128-bit Pseudo Random Number Generators (PRNG) and Modulo (MOD) operations which can be easily implemented on low-cost passive tags and hence achieves EPC C1G2 compliance.

RFID tags : grouping proof with forward security

Several grouping proof protocols have been proposed over the years but they are either found to be vulnerable to certain attacks or do not comply with EPC Class-1 Gen-2 (C1G2) standard because they use hash functions or other complex encryption schemes. Among other requirements, synchronization of keys, forward security, dependence, detecting illegitimate tags, eliminating unwanted tag processing and denial-of-proof (DoP) attacks have not been fully addressed by many. Our protocol addresses these important gaps and is based on simple XOR encryption and 128-bit Pseudo Random Number Generators (PRNG), operations that are easily implemented on low-cost passive tags and hence achieves EPC C1G2 compliance.

Secure ownership transfer in multi-tag/multi-owner passive RFID systems

In this paper we propose a secure ownership transfer protocol for a multi-tag and multi-owner RFID environment. Most of the existing work in this area do not comply with the EPC Global Class-1 Gen-2 (C1G2) standard since they use expensive hash operations or sophisticated encryption schemes that cannot be implemented on low-cost passive tags that are highly resource constrained. Our work aims to fill this gap by proposing a protocol based on simple XOR and 128-bit Pseudo Random Number Generators (PRNG), operations that can be easily implemented on low-cost passive RFID tags. The protocol thus achieves EPC C1G2 compliance while meeting the security requirements. Also, our protocol provides additional protection using a blind-factor to prevent tracking attacks.

Secure ownership transfer for multi-tag multi-owner passive RFID environment with individual-owner-privacy

In this paper we propose a secure ownership transfer protocol for a multi-tag multi-owner RFID environment that provides individual-owner-privacy. To our knowledge, the existing schemes do not provide individual-owner-privacy and most of the existing schemes do not comply with the EPC Global Class-1 Gen-2 (C1G2) standard since the protocols use expensive hash operations or sophisticated encryption schemes that cannot be implemented on low-cost passive tags that are highly resource constrained. Our work aims to fill these gaps by proposing a protocol that provides individual-owner-privacy, based on simple XOR and 128-bit pseudo-random number generators (PRNG), operations that are easily implemented on low-cost RFID tags while meeting the necessary security requirements thus making it a viable option for large scale implementations. Our protocol also provides additional protection by hiding the pseudo-random numbers during all transmissions using a blind-factor to prevent tracking attacks.

Zero knowledge grouping proof protocol for RFID EPC C1G2 Tags

In this paper, we propose a novel zero knowledge grouping proof protocol for RFID Systems. Over the years, several protocols have been proposed in this area but they are either found to be vulnerable to certain attacks or do not comply with the EPC Class 1 Gen 2 (C1G2) standard because they use hash functions or other complex encryption schemes. Also, the unique design requirements of grouping proofs have not been fully addressed by many. Our protocol addresses these important security and design gaps in grouping proofs. We present a novel approach based on pseudo random squares and quadratic residuosity to realize a zero knowledge system. Tag operations are limited to functions such as modulo (MOD), exclusive-or (XOR) and 128 bit Pseudo Random Number Generators (PRNG). These can be easily implemented on passive tags and hence achieves compliance with the EPC Global standard while meeting the security requirements.

Generalized pseudo-likelihood estimates for markov random fields on lattice

In this paper we generalize Besag's pseudo-likelihood function for spatial statistical models on a region of a lattice. The correspondingly defined maximum generalized pseudo-likelihood estimates (MGPLEs) are natural extensions of Besag's maximum pseudo-likelihood estimate (MPLE). The MGPLEs connect the MPLE and the maximum likelihood estimate. We carry out experimental calculations of the MGPLEs for spatial processes on the lattice. These simulation results clearly show better performances of the MGPLEs than the MPLE, and the performances of differently defined MGPLEs are compared. These are also illustrated by the application to two real data sets.

On the permutation behaviour of Dickson polynomials of the second kind

The known permutation behaviour of the Dickson polynomials of the second kind in characteristic 3 is expanded and simplified.

Chromatic and luminance losses with multiple sclerosis and optic neuritis measured using dynamic random luminance contrast noise

We measured thresholds for detecting changes in colour and in luminance contrast in observers with multiple sclerosis (MS) and/or optic neuritis (ON) to determine whether reduced sensitivity occurs principally in red-green or blue-yellow second-stage chromatic channels or in an achromatic channel. Colour thresholds for the observers with MS/ON were higher in the red-green direction than in the blue-yellow direction, indicating greater levels of red-green loss than blue-yellow loss. Achromatic thresholds were raised less than either red-green or blue-yellow thresholds, showing less luminance-contrast loss than chromatic loss. With the MS/ON observers, blue-yellow and red-green thresholds were positively correlated but increasing impairment was associated with more rapid changes in red-green thresholds than blue-yellow thresholds. These findings indicate that demyelinating disease selectively reduces sensitivity to colour vision over luminance vision and red-green colours over blue-yellow colours.

Class library ranlip for multivariate nonuniform random variate generation

This paper describes generation of nonuniform random variates from Lipschitz-continuous densities using acceptance/rejection, and the class library _ranlip which implements this method. It is assumed that the required distribution has Lipschitz-continuous density, which is either given analytically or as a black box. The algorithm builds a piecewise constant upper approximation to the density (the hat function), using a large number of its values and subdivision of the domain into hyperrectangles. The class library _ranlip provides very competitive preprocessing and generation times, and yields small rejection constant, which is a measure of efficiency of the generation step. It exhibits good performance for up to five variables, and provides the user with a black box nonuniform random variate generator for a large class of distributions, in particular, multimodal distributions. It will be valuable for researchers who frequently face the task of sampling from unusual distributions, for which specialized random variate generators are not available.

Universal nonuniform random vector generator based on acceptance-rejection

The acceptance/rejection approach is widely used in universal nonuniform random number generators. Its key part is an accurate approximation of a given probability density from above by a hat function. This article uses a piecewise constant hat function, whose values are overestimates of the density on the elements of the partition of the domain. It uses a sawtooth overestimate of Lipschitz continuous densities, and then examines all local maximizers of such an overestimate. The method is applicable to multivariate multimodal distributions. It exhibits relatively short preprocessing time and fast generation of random variates from a very large class of distributions