Sigmoid(x): secure distributed network storage

Secure data storage is a serious problem for computer users today, particularly in enterprise environments. As data requirements grow, traditional approaches of secured silos are showing their limitations. They represent a single – or at least, limited – point of failure, and require significant, and increasing, maintenance and overhead. Such solutions are totally unsuitable for consumers, who want a ‘plug and play’ secure solution for their increasing datasets – something with the ubiquity of access of Facebook or webmail. Network providers can provide centralised solutions, but that returns us to the first problem. Sigmoid(x) takes a completely different approach – a scalable, distributed, secure storage mechanism which shares data storage between the users themselves

Implementation of QoS onto virtual bus network

Quality of Service (QoS) is a key issue in a multimedia environment because multimedia applications are sensitive to delay. The virtual bus architecture is a hierarchical access network structure that has been proposed to simplify network signaling. The network employs an interconnection of hierarchical database to support advanced routing of the signaling and traffic load. Therefore, the requirements and management of quality of service is important in the virtual bus network particularly to support multimedia applications. QoS and traffic parameters are specified for each class type and the OMNeT model has been described

Estimating commitment in a digital market place environment

The future generation of mobile communication shall be a convergence of mobile telephony and information systems which promises to change people's lives by enabling them to access information when, where and how they want. It presents opportunities to offer multimedia applications and services that meet end-toend service requirements. The Digital Marketplace framework will enable users to have separate contracts for different services on a per call basis. In order for such a framework to function appropriately, there has to be some means for the network operator to know in advance if its network will be able to support the user requirements. This paper discusses the methods by which the network operator will be able to determine if the system will be able to support another user of a certain service class and therefore negotiate parameters like commitment, QoS and the associated cost for providing the service, thus making the Digital Marketplace wor

Economics of intelligent selection of wireless access networks in a market-based framework : a game-theoretic approach

The Digital Marketplace is a market-based framework where network operators offer communications services with competition at the call level. It strives to address a tussle between the actors involved in a heterogeneous wireless access network. However, as with any market-like institution, it is vital to analyze the Digital Marketplace from the strategic perspective to ensure that all shortcomings are removed prior to implementation. In this paper, we analyze the selling mechanism proposed in the Digital Marketplace. The mechanism is based on a procurement first-price sealed-bid auction where the network operators represent the sellers/bidders, and the end-user of a wireless service is the buyer. However, this auction format is somewhat unusual as the winning bid is a composition of both the network operator’s monetary bid and their reputation rating. We create a simple economic model of the auction, and we show that it is mathematically intractable to derive the equilibrium bidding behavior when there are N network operators, and we make only generic assumptions about the structure of the bidding strategies. We then move on to consider a scenario with only two network operators, and assume that network operators use bidding strategies which are linear functions of their costs. This results in the derivation of the equilibrium bidding behavior in that scenario

Delta modulation techniques for low bit-rate digital speech encoding

Includes bibliography.Two new hybrid companding delta modulators for speech encoding are presented here. These modulators differ from the Hybrid Companding Delta Modulator (HCDM) proposed by Un et al in that the two new encoders employ Song Voice Adaptation as the basis of the instantaneous compandor, rather than Constant Factor adaptation. A detailed analysis of the performance, both objective and subjective, of these hybrid codecs has been carried out. Results show that overall the two codecs developed as part of this project are better than the HCDM codec. In addition the new codecs offer simpler implementation in digital hardware than the HCDM. A Computer Aided Test (CAT) system has been developed to simplify the design and test processes for speech codecs

Timing verification of dynamically reconfigurable logic for Xilinx Virtex FPGA series

This paper reports on a method for extending existing VHDL design and verification software available for the Xilinx Virtex series of FPGAs. It allows the designer to apply standard hardware design and verification tools to the design of dynamically reconfigurable logic (DRL). The technique involves the conversion of a dynamic design into multiple static designs, suitable for input to standard synthesis and APR tools. For timing and functional verification after APR, the sections of the design can then be recombined into a single dynamic system. The technique has been automated by extending an existing DRL design tool named DCSTech, which is part of the Dynamic Circuit Switching (DCS) CAD framework. The principles behind the tools are generic and should be readily extensible to other architectures and CAD toolsets. Implementation of the dynamic system involves the production of partial configuration bitstreams to load sections of circuitry. The process of creating such bitstreams, the final stage of our design flow, is summarized

Evils of Modern Stables

Portions of veterinarian James Irvine Lupton\u27s book on horse management that deal with the problems of confinement husbandry practices have been selected as a significant historical record of humane concerns that were documented one hundred years ago. While the author\u27s descriptive prose may lack scientific objectivity, it does express a common sense morality and the subjective and intuitive observations and conclusions of an experienced veterinarian who clearly respects and understands the horse. His words bespeak of a bygone era where the care or husbandry of animals was both an art and a science, a discipline based upon empathy, compassion and factual knowledge. How far indeed have we progressed, ethically and technologically, in improving the husbandry of domesticated animals, such as the horse, since 1884? While conditions may be more sanitary and diseases better understood, prevented, and treated, it is a fact that stabled horses in 1984 are too often kept under comparable conditions of extreme deprivation and show the same behavioral pathologies that Lupton so clearly describes

Time constraints on the formation of lithospheric mantle beneath cratons: a re-Os isotope and platinum group element study of peridotite xenoliths from northern Canada and Lesotho,

Understanding the generation and evolution of cratonic lithospheric keels requires detailed knowledge of their age, timescale of formation, and the relationship between the crust and mantle part of the lithosphere. The Re-Os isotope system has been instrumental in providing an improved understanding of the timing of formation of cratonic lithospheric keels because of the large fractionation of Re from Os during mantle melting and the relative immunity of Os during mantle metasomatism. This study uses combined full PGE (Platinum Group Elements; Os, Ir, Ru, Pt, Pd) and Re-Os isotope analyses to place better constraints on the significance of Re-Os model ages in sub-continental lithospheric mantle suites from northern Canada and Lesotho, southern Africa. When combined with major-element studies, the coherence of major-elements with PGE fractionation trends, (Pd/Ir)(_n9), provide a firm basis for evaluating the significance of T(_RD) and T(_MA) model ages obtained from Re-Os isotope systematics. The fractionation of PGEs track melt depletion and melt enrichment end-member processes, and allow us to discern samples which have experienced Pd and Re enrichment at varying stages. The Re-Os isotope and PGE analyses of peridotite xenoliths from the Jericho kimberlite clearly indicate the presence of Archean mantle beneath the Slave craton (T(_RD) range from 3.1 to 2.6 Ga), extending down into the high-temperature garnet facies. Archean ages are also evident in peridotite xenoliths from Somerset Island in the Churchill Province (oldest T(_RD) ca. 2.8 Ga). This is the first indication of Archean sub continental lithosphere beneath this region that is characterised by early to mid Proterozoic crustal ages. Some peridotites from the Jericho and Somerset Island peridotite suites have noticeably disturbed Re-Os isotope and PGE systematics and produce anomalously young model ages for cratonic lithospheric mantle overall. Many of the young model ages observed at Jericho and Somerset Island are coincident with major tectonomagmatic events manifested in the overlying crust and may represent new lithospheric mantle added at this time. Depleted peridotite xenoliths from Lesotho (Kaapvaal craton) have very tightly clustered T(_RD) model ages (2.8 ± 0.1 Ga, n = 26). The model age of the lithospheric mantle beneath this region is significantly younger than the age of the oldest overlying crust on the Kaapvaal craton, but correlates well with the end of major crustal differentiation and stabilisation of the Kaapvaal craton. This indicates that large fractionation of lithospheric mantle beneath the Kaapvaal craton could have formed in the late-Archean

Investigating the security of android security applications

Encryption is commonly used to provide confidentiality of sensitive or personal information when held on smartphones. While many Android devices feature inbuilt full-disk encryption as a precaution against theft of a device, this is not available on all devices, and doesn't provide security against a device which is turned on and in use. For this reason, a wide variety of applications are available within the Google Play Store, offering to encrypt user data. Modern, strong encryption offers strong assurances of confidentiality when used correctly, although the fundamental cryptographic primitives are complex, with many opportunities for mistakes to be made. The security of a number of implementations of Android-based encryption applications is investigated. Highly popular applications, including those by Google-endorsed "Top Developers", are considered. A number of major weaknesses in the implementation of encryption within these applications is presented. This highlights the importance of both well-audited open-source cryptographic implementations, as well as the underlying cryptographic algorithms themselves, given the vulnerabilities identified in these applications. In many cases, there was no encryption in use by the application, and file headers were undergoing trivial static obfuscation, such that files would appear corrupted. In other cases, encryption algorithms were used, but with significant implementational errors. In these cases, plaintext recovery was still possible, due to the use of static keys for every installation of the app, and the re-use of cipher initialisation vectors