45941694
Electronic Payment Systems with Fair On-line Verification
Electronic payment systems have been intensively studied in recent years. Generally speaking, e-payment systems can be classified into two categories, i.e., the systems with on-line verification and the systems with off-line verification. The former establishes security under the principle of preventionbefore-the-fact while the latter’s security is based on the principle of detectionafter-the-fact. On-line systems are less risky, thus more likely to be adopted by the business community. A critical issue for on-line systems is how to make a transaction fair to each transacting party such that neither party can gain advantages over the other party in a transaction. This can be addressed with a fundamental technique of fair on-line verification. In this paper, we propose a solution to fair on-line verification for electronic payment systems, in which the customer gives verifiable encryption (by a TTP’s public key) of the digital money to the shop for on-line verification, instead of giving shop the money itself. The paper not only shows the principle of applying verifiable encryption to e-payment systems, but also focuses on building up a concrete payment system.
40659634
Observations on Non-repudiation
This paper discusses non-repudiation services regarding the transfer of a message and classifies the roles of trusted third parties involved in non-repudiation services. We examine the selective receipt problem and the generation of time evidence, analyse the current state of the ISO/IEC 13888 drafts on non-repudiation mechanisms, and present a fair non-repudiation protocol including time evidence to promote the development of these drafts.
26863874
Efficient Signature Validation Based on a New PKI
Digital signatures usually serve as irrefutable cryptographic evidence to support dispute resolution in electronic transactions. Trusted time-stamping and certificate revocation services, although very costly in practice, must be available to prevent big loss due to compromising of the signing key. In this paper, we employ a revocation-free public-key framework to improve the efficiency in maintaining the validity of digital signatures as non-repudiation evidence. The new PKI allows an end user to control the validity of his own public-key certificate and enables certificate verification without retrieving the revocation information from the CA. Based on this new PKI, we could validate generic digital signatures using a TSA only. Moreover, we could validate forward-secure digital signatures without the TTP’s involvement.
1909548
An intensive survey of fair non-repudiation protocols
With the phenomenal growth of the Internet and open networks in general, security services, such as non-repudiation, become crucial to many applications. Non-repudiation services must ensure that when Alice sends some information to Bob over a network, neither Alice nor Bob can deny having participated in a part or the whole of this communication. Therefore a fair non-repudiation protocol has to generate non-repudiation of origin evidences intended to Bob, and non-repudiation of receipt evidences destined to Alice. In this paper, we clearly define the properties a fair non-repudiation protocol must respect, and give a survey of the most important non-repudiation protocols without and with trusted third party (TTP). For the later ones we discuss the evolution of the TTP's involvement and, between others, describe the most recent protocol using a transparent TTP. We also discuss some ad-hoc problems related to the management of non-repudiation evidences.
14818527
Agent-mediated non-repudiation protocols
Non-repudiation is a security service that provides cryptographic evidence to support the settlement of disputes in electronic commerce. In commercial transactions, an intermediary (or agent) might be involved to help transacting parties to conduct their business. Nevertheless, such an intermediary may not be fully trusted. In this paper, we propose agent-mediated non-repudiation protocols and analyze their security requirements. We first present a simple scenario with only one recipient, followed by a more complicated framework where multiple recipients are involved and collusion between them is possible. We also identify applications that could take advantage of these agent-mediated nonrepudiation protocols. � 2004 Elsevier B.V. All rights reserved.
2500764
Securing digital signatures for non-repudiation
Dispute of transactions is a common problem that could jeopardise business. Hence non-repudiation services are essential in business transactions which provide evidence to enable dispute resolution. To be eligible as non-repudiation evidence, the digital signature on an electronic document should remain valid until its expiry date which is specified by some non-repudiation policy. The conventional approaches are either inefficient or insecure to achieve non-repudiation in electronic commerce. This article presents a practical scheme to secure digital signatures as non-repudiation evidence with an adjustable degree of risk.
2326563
Improving Database Performance on Simultaneous Multithreading Processors
Simultaneous multithreading (SMT) allows multiple threads to supply instructions to the instruction pipeline of a superscalar processor. Because threads share processor resources, an SMT system is inherently different from a multiprocessor system and, therefore, utilizing multiple threads on an SMT processor creates new challenges for database implementers.We investigate three thread-based techniques to exploit SMT architectures on memory-resident data. First, we consider running independent operations in separate threads, a technique applied to conventional multi-processor systems. Second, we describe a novel implementation strategy in which individual operators are implemented in a multi-threaded fashion. Finally, we introduce a new data-structure called a work-ahead set that allows us to use one of the threads to aggressively preload data into the cache.We evaluate each method with respect to its performance, implementation complexity, and other measures. We also provide guidance regarding when and how to best utilize the various threading techniques. Our experimental results show that by taking advantage of SMT technology we achieve a 30% to 70% improvement in throughput over single threaded implementations on in-memory database operations.
1638969
Verification - a method of enhancing the recognizers of isolated and touching handwritten numerals
Abstract This paper investigates verification schemes and their applications to the recognition of both isolated and touching handwritten numerals. Definitions and functionality analyses of the verifiers are given. The measurement of precision rate is used to assess the system reliability in a class-specific manner. Verification-enhanced systems are proposed with extensive experiments conducted on both isolated and touching numerals. Two databases for touching numerals are built/organized to serve as standard data sets. Experimental results indicate a substantial improvement in system precision rates by the verification scheme, which proves the effectiveness of the proposed systems and justifies the important role of verifiers in OCR systems.
15147736
Exploiting medium access diversity in rate adaptive wireless LANs
Recent years have seen the growing popularity of multi-rate wireless network devices (e.g., 802.11a cards) that can exploit variations in channel conditions and improve overall network throughput. Concurrently, rate adaptation schemes have been developed that selectively increase data transmissions on a link when it offers good channel quality. In this paper, we propose a Medium Access Diversity (MAD) scheme that leverages the benefits of rate adaptation schemes by aggressively exploiting multiuser diversity. The basic mechanism of MAD is to obtain instantaneous channel condition information from multiple receivers and selectively transmit data to a receiver that improves the overall throughput of the network, while maintaining temporal fairness among multiple data flows. We identify and address the challenges in the design and implementation of MAD's three phases: channel probing, data transmission, and receiver scheduling. We also use analytical models to examine the tradeoff between network performance improvement and overhead of channel probing, and derive an asymptotic performance bound for the receiver scheduling algorithms used by MAD. Results from the analysis and the extensive simulations demonstrate that, on average, MAD can improve the overall throughput of IEEE 802.11 wireless LANs by 50% as compared with the best existing rate adaptation scheme.
27166902
Toward automatic annotation of in situ mRNA expression patterns of drosophila embryos
The in situ mRNA hybridization gene expression pattern images of Drosophila melanogaster in the course of embryogenesis provide spatial-temporal information of the expression patterns of a target gene. This information is critical for understanding the roles of genes during the development of embryos. Currently, the annotation of these images is often done by manually assigning a subset of image ontology terms to the images. This approach is time consuming and depends heavily on the consistency of the experts. Alternatively, if the annotation process can be automated or semi-automated, efficiency and consistency are likely to be greatly enhanced. We formulate this task as a pattern classification problem, and present preliminary results. We consider both the template-based global matching and the multi-objective classification based on neural networks (e.g. multi-layer perceptron). We develop a method to combine them to optimize efficiency and accuracy. This method has been applied to the gene expression pattern image database generated by the Berkeley Drosophila Genome Project.
17429132
Rule-base technique for component adaptation to support QoS-based reconfiguration
Many critical application systems require reconfigurability in order to adapt under changing environment. To achieve system reconfigurability, it is possible to use adaptation mechanisms that are external to components or to use parameterized components. This paper focuses on making components reconfigurable in terms of QoS tradeoffs. We propose a new component parameterization technique which can transform individual components to reconfigurable ones such that they can support various QoS tradeoffs to achieve overall system QoS requirements. The parameterized components can be used to develop both statically and dynamically reconfigurable systems. The proposed technique is rule based, which provides flexibility and extensibility to enhance and improve the technique. A tool set has been developed based on the proposed technique to achieve semi-automated component parameterization.