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.
12889204
Further analysis of the Internet key exchange protocol
Secure communication over the Internet becomes an essential requirement for any value-added Internet application. The use of cryptography for secure communication brings out the requirement of cryptographic key management. This paper examines some security issues on the Internet Key Exchange (IKE) protocol specified in RFC 2409. The investigation is intended for clarifying some specification ambiguities in RFC 2409 and facilitating a correct implementation of the IKE protocol.
28799262
Cryptanalysis of Chu's DCT based watermarking scheme
In 2003, Chu proposed an oblivious watermarking algorithm by modifying the CKLS scheme proposed by Cox, Kilian, Leighton, and Shamoon in 1997, known as the CKLS scheme. In this correspondence, we report that the modification presented by Chu is susceptible to a suitably modified attack devised by Das and Maitra in 2004. In fact, the experimental results show that Chu's scheme is even weaker than the CKLS scheme in terms of our attack.
14329481
Analysis and Improvement of Micali's Fair Contract Signing Protocol
In PODC 2003, Micali presented a fair electronic exchange protocol for contract signing with an invisible trusted party [17]. The protocol was filed as a US patent No 5666420 in 1997 [16]. In the protocol, two mutually distrusted parties exchange their commitments to a contract in a fair way such that either each of them can obtain the other’s commitment, or neither of them does. The protocol is optimistic in the sense that the trusted party need not be involved in the protocol unless a dispute occurs. In this paper, we show that Micali’s protocol cannot achieve the claimed fairness. In resolving a dispute, the trusted party may face a dilemma situation that no matter what it does, one of the exchanging parties can succeed in cheating. In other words, there is always a party who can get the other’s commitment without the other party obtaining his. We further propose a revised version of contract signing protocol that preserves fairness while remaining optimistic.
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.
22074274
Cryptanalysis of Barni et al. Watermarking Scheme
In this paper, we analyze a wavelet based watermarking scheme proposed by Barni et al in 2001. The said scheme modifies high frequency wavelet coefficients to embed a watermark in an image. The scheme employs well known HVS model during embedding to embed the watermark in a perceptually transparent manner. Here we present a successful cryptanalysis of the scheme using single watermarked copy. In the process of cryptanalysis, we recover the watermark signal from the marked image and the attack is similar to cryptographic key recovery attack. Furthermore, we not only successfully recover the secret watermark signal from the attacked image, but also we are able to remove the watermark. This raises a serious question about the security and usability of the watermarking scheme in any practical system.
17829598
Maya: a Multi-Paradigm Network Modeling Framework
This paper presents Maya, a multi-paradigm, scalableand extensible network modeling framework for emulatingdistributed applications. A novel three-tier architecture isproposed to integrate three disparate modeling paradigms,namely, discrete event models, analytical models and physicalnetwork interfaces into one unified framework of Maya.As the first effort to integrate all three paradigms intoone framework, this paper discusses the implementationsof Maya using Qualnet, fluid flow based TCP model andphysical network interface. It addresses the performanceissues involved in attaining the real time constraints imposedby distributed applications and demonstrates the effectivenessof using analytical models in Maya. Furthermore, it identifies the negative impact on real time performance through the computation intensive ordinary differential equation (ODE) solver in the fluid flow model. A new approach to interleaved executions of the fluid flow model is proposed to hide ODE solver turnaround time. As a result, the percentage of packets missing their deadlines has been reduced from more than 6% to less than 0.2%.
1321567
A multi-resolution block storage model for database design
We propose a new storage model called MBSM (multiresolution block storage model) for laying out tables on disks. MBSM is intended to speed up operations such as scans that are typical of data warehouse workloads. Disk blocks are grouped into "super-blocks," with a single record stored in a partitioned fashion among the blocks in a superblock. The intention is that a scan operation that needs to consult only a small number of attributes can access just those blocks of each super-block that contain the desired attributes. To achieve good performance given the physical characteristics of modern disks, we organize super-blocks on the disk into fixed-size "mega-blocks." Within a megablock, blocks of the same type (from various super-blocks) are stored contiguously. We describe the changes needed in a conventional database system to manage tables using such a disk organization. We demonstrate experimentally that MBSM outperforms competing approaches such as NSM (N-ary storage model), DSM (decomposition storage model) and PAX (partition attributes across), for I/O bound decision-support workloads consisting of scans in which not all attributes are required. This improved performance comes at the expense of single-record insert and delete performance; we quantify the trade-offs involved. Unlike DSM, the cost of reconstructing a record from its partitions is small. MBSM stores attributes in a vertically partitioned manner similar to PAX, and thus shares PAX's good CPU cache behavior. We describe methods for mapping attributes to blocks within super-blocks in order to optimize overall performance, and show how to tune the super-block and mega-block sizes.
2774973
Understanding Human-Computer Interactions in Map Revision
It is difficult to track, parse and model human-computer interactions during editing and revising of documents, but it is necessary if we are to develop automated technologies that will aid or replace humans. This paper introduces a system for accessing and recording a stream of events related to human actions in a real-time cartographic map revision system. The recorded events are parsed into a sequence of meaningful user actions and an action representation in XML format is generated. We also report results of experiments on predicting user actions such as view changes, edits, road tracking/production using hidden Markov models.
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.
1003875
A software enhancement system for embedded software development
This paper proposes a rule-based expert system model to assist developers in enhancing the quality of embedded software. The expert system supports semi-automated source code enhancements from multiple perspectives including optimization, reconfiguration to achieve quality of service (QoS) trade-offs, conformance to coding standards, etc., by defining a rule base that is composed of modularized and extensible rule sets. The rule sets are composed of re-usable rules; the rules capture the in-depth knowledge of different software experts. The expert system also adopts a technique to support automated fact generation. This allows the expert system to support processing programs developed in different programming languages