New Zero-knowledge Undeniable Signatures - Forgery of Signature Equivalent to Factorisation

We propose a new zero-knowledge undeniable signature scheme which is based on the intractability of computing high-order even powers modulo a composite. The new scheme has a number of desirable properties: (i) forgery of a signature (including existential forgery) is proven to be equivalent to factorisation, (ii) perfect zero-knowledge, (iii) efficient protocols for signature verification and non-signature denial: both measured by $O(\log k)$ (multiplications) where $1/k$ bounds the probability of error. For a denial protocol, this performance is unprecedented

VSH, an efficient and provable collision-resistant hash function

We introduce VSH, very smooth hash, a new S-bit hash function that is provably collision-resistant assuming the hardness of finding nontrivial modular square roots of very smooth numbers modulo an S-bit composite. By very smooth, we mean that the smoothness bound is some fixed polynomial function of S. We argue that finding collisions for VSH has the same asymptotic complexity as factoring using the Number Field Sieve factoring algorithm, i.e., subexponential in S. VSH is theoretically pleasing because it requires just a single multiplication modulo the S-bit composite per ω(5) message-bits (as opposed to O(log S) message-bits for previous provably secure hashes). It is relatively practical. A preliminary implementation on a 1GHz Pentium III processor that achieves collision resistance at least equivalent to the difficulty of factoring a 1024-bit USA modulus, runs at 1.1 MegaByte per second, with a moderate slowdown to 0.7MB/s for 2048-bit RSA security. VSH can be used to build a fast, provably secure randomised trapdoor hash function, which can be applied to speed up provably secure signature schemes (such as Cramer-Shoup) and designated-verifier signatures. © International Association for Cryptologic Research 2006

Quantum correlations in continuous variable mixed states : from discord to signatures

This thesis studies continuous variable mixed states with the aim of better understanding the fundamental behaviour of quantum correlations in such states, as well as searching for applications of these correlations. I first investigate the interesting phenomenon of discord increase under local loss and explain the behaviour by considering the non-orthogonality of quantum states. I then explore the counter-intuitive result where entanglement can be created by a passive optical beamsplitter, even if the input states are classical, as long as the input states are part of a larger globally nonclassical system. This result emphasises the importance of global correlations in a quantum state, and I propose an application of this protocol in the form of quantum dense coding. Finally, I develop a quantum digital signature protocol that can be described entirely using the continuous variable formalism. Quantum digital signatures provide a method to ensure the integrity and provenance of a message using quantum states. They follow a similar method to quantum key distribution (QKD), but require less post-processing, which means they can sometimes be implemented over channels that are inappropriate for QKD. The method I propose uses homodyne measurement to verify the signature, unlike previous protocols that use single photon detection. The single photon detection of previous methods is designed to give unambiguous results about the signature, but this comes at the cost of getting no information much of the time. Using homodyne detection has the advantage of giving results all the time, but this means that measurement results always have some ambiguity. I show that, even with this ambiguity, the signature protocol based on homodyne measurement outperforms previous protocols, with the advantage enhanced when technical considerations are included. Therefore this represents an interesting new direction in the search for a practical quantum digital signature scheme

New zero-knowledge undeniable signatures Forgery of signature equivalent to factorisation

SIGLEAvailable from British Library Document Supply Centre-DSC:4335.26205(2001-36) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

A comparison of the CAR and DAGAR spatial random effects models with an application to diabetics rate estimation in Belgium

When hierarchically modelling an epidemiological phenomenon on a finite collection of sites in space, one must always take a latent spatial effect into account in order to capture the correlation structure that links the phenomenon to the territory. In this work, we compare two autoregressive spatial models that can be used for this purpose: the classical CAR model and the more recent DAGAR model. Differently from the former, the latter has a desirable property: its ρ parameter can be naturally interpreted as the average neighbor pair correlation and, in addition, this parameter can be directly estimated when the effect is modelled using a DAGAR rather than a CAR structure. As an application, we model the diabetics rate in Belgium in 2014 and show the adequacy of these models in predicting the response variable when no covariates are available

A Statistical Approach to the Alignment of fMRI Data

Multi-subject functional Magnetic Resonance Image studies are critical. The anatomical and functional structure varies across subjects, so the image alignment is necessary. We define a probabilistic model to describe functional alignment. Imposing a prior distribution, as the matrix Fisher Von Mises distribution, of the orthogonal transformation parameter, the anatomical information is embedded in the estimation of the parameters, i.e., penalizing the combination of spatially distant voxels. Real applications show an improvement in the classification and interpretability of the results compared to various functional alignment methods

Factors Influencing Customer Satisfaction towards E-shopping in Malaysia

Online shopping or e-shopping has changed the world of business and quite a few people have decided to work with these features. What their primary concerns precisely and the responses from the globalisation are the competency of incorporation while doing their businesses. E-shopping has also increased substantially in Malaysia in recent years. The rapid increase in the e-commerce industry in Malaysia has created the demand to emphasize on how to increase customer satisfaction while operating in the e-retailing environment. It is very important that customers are satisfied with the website, or else, they would not return. Therefore, a crucial fact to look into is that companies must ensure that their customers are satisfied with their purchases that are really essential from the ecommerce’s point of view. With is in mind, this study aimed at investigating customer satisfaction towards e-shopping in Malaysia. A total of 400 questionnaires were distributed among students randomly selected from various public and private universities located within Klang valley area. Total 369 questionnaires were returned, out of which 341 questionnaires were found usable for further analysis. Finally, SEM was employed to test the hypotheses. This study found that customer satisfaction towards e-shopping in Malaysia is to a great extent influenced by ease of use, trust, design of the website, online security and e-service quality. Finally, recommendations and future study direction is provided. Keywords: E-shopping, Customer satisfaction, Trust, Online security, E-service quality, Malaysia

The adequacy and efficacy of anti-money laundering legislations within the context of electronic banking and informal remittance systems in developing countries with particular reference to Nigeria and South Africa

In recent times, international, regional and local legislation has been couched to strengthen anti-corruption institutions and deter corrupt public officials from syphoning public wealth for their benefits, but this has continued unabated in spite of some successes recorded from these anti-graft agencies. Electronic banking notable for timeliness in executing transfers have helped in facilitating ease of doing business and as well accelerated the transfer of illicit wealth to secrecy jurisdictions. So regardless of internal and prudential controls instituted by regulatory authorities to ensure transparency in handling transactions and the reporting requirements for suspicious transactions, money laundering persists. Tracing and recovering the loot becomes another financial, legal and inter-state hurdle on the part of law enforcement agencies while the perpetrators live in exquisite luxury believing that the loot is their fair share of the ‘national cake.' This dissertation sought to assess the adequacy and efficacy of anti-money laundering legislation given the complexities of the local environment: namely nepotism, weak institutions, and predominance of a cash-based economy, lack of independence and the politicisation of corruption. First, we consider the enormity of the problem of corruption and its effect on developing countries with due regard to security, judicial fairness and stability of the economy. After that is an examination of international and local money laundering initiatives with a considerable emphasis on the United Nations Convention against Corruption and the role of the Financial Intelligence Unit in providing intelligence for tracing of corrupt proceeds. The researcher asserts that anti-money laundering legislation will be efficacious where good governance prevails and the incentives for corruption including nepotism and prebendal attitudes are discouraged. A State, which provides social safety nets for its populace, would strengthen the anticorruption fight thereby discouraging new entrants into public office positions from graft and abuse of those positions of authority