7,763 research outputs found

    The selection, appraisal and retention of digital scientific data: dighlights of an ERPANET/CODATA workshop

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    CODATA and ERPANET collaborated to convene an international archiving workshop on the selection, appraisal, and retention of digital scientific data, which was held on 15-17 December 2003 at the Biblioteca Nacional in Lisbon, Portugal. The workshop brought together more than 65 researchers, data and information managers, archivists, and librarians from 13 countries to discuss the issues involved in making critical decisions regarding the long-term preservation of the scientific record. One of the major aims for this workshop was to provide an international forum to exchange information about data archiving policies and practices across different scientific, institutional, and national contexts. Highlights from the workshop discussions are presented

    Chip and Skim: cloning EMV cards with the pre-play attack

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    EMV, also known as "Chip and PIN", is the leading system for card payments worldwide. It is used throughout Europe and much of Asia, and is starting to be introduced in North America too. Payment cards contain a chip so they can execute an authentication protocol. This protocol requires point-of-sale (POS) terminals or ATMs to generate a nonce, called the unpredictable number, for each transaction to ensure it is fresh. We have discovered that some EMV implementers have merely used counters, timestamps or home-grown algorithms to supply this number. This exposes them to a "pre-play" attack which is indistinguishable from card cloning from the standpoint of the logs available to the card-issuing bank, and can be carried out even if it is impossible to clone a card physically (in the sense of extracting the key material and loading it into another card). Card cloning is the very type of fraud that EMV was supposed to prevent. We describe how we detected the vulnerability, a survey methodology we developed to chart the scope of the weakness, evidence from ATM and terminal experiments in the field, and our implementation of proof-of-concept attacks. We found flaws in widely-used ATMs from the largest manufacturers. We can now explain at least some of the increasing number of frauds in which victims are refused refunds by banks which claim that EMV cards cannot be cloned and that a customer involved in a dispute must therefore be mistaken or complicit. Pre-play attacks may also be carried out by malware in an ATM or POS terminal, or by a man-in-the-middle between the terminal and the acquirer. We explore the design and implementation mistakes that enabled the flaw to evade detection until now: shortcomings of the EMV specification, of the EMV kernel certification process, of implementation testing, formal analysis, or monitoring customer complaints. Finally we discuss countermeasures

    Clathrate formation and dissociation in vapor/water/ice/hydrate systems in SBA-15, sol-gel and CPG porous media, as probed by NMR relaxation, novel protocol NMR cryoporometry, neutron scattering and ab initio quantum-mechanical molecular dynamics simulation

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    The Gibbs-Thomson effect modifies the pressure and temperature at which clathrates occur, hence altering the depth at which they occur in the seabed. Nuclear magnetic resonance (NMR) measurements as a function of temperature are being conducted for water/ice/ hydrate systems in a range of pore geometries, including templated SBA-15 silicas, controlled pore glasses and sol-gel silicas. Rotator-phase plastic ice is shown to be present in confined geometry, and bulk tetrahydrofuran hydrate is also shown to probably have a rotator phase. A novel NMR cryoporometry protocol, which probes both melting and freezing events while avoiding the usual problem of supercooling for the freezing event, has been developed. This enables a detailed probing of the system for a given pore size and geometry and the exploration of differences between hydrate formation and dissociation processes inside pores. These process differences have an important effect on the environment, as they impact on the ability of a marine hydrate system to re-form once warmed above a critical temperature. Ab initio quantum-mechanical molecular dynamics calculations are also being employed to probe the dynamics of liquids in pores at nanometric dimensions

    EMV: Why Payment Systems Fail

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    What lessons might we learn from the chip cards used for payments in Europe, now that the U.S. is adopting them too?</jats:p

    Quasiharmonic elastic constants corrected for deviatoric thermal stresses

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    The quasiharmonic approximation (QHA), in its simplest form also called the statically constrained (SC) QHA, has been shown to be a straightforward method to compute thermoelastic properties of crystals. Recently we showed that for non-cubic solids SC-QHA calculations develop deviatoric thermal stresses at high temperatures. Relaxation of these stresses leads to a series of corrections to the free energy that may be taken to any desired order, up to self-consistency. Here we show how to correct the elastic constants obtained using the SC-QHA. We exemplify the procedure by correcting to first order the elastic constants of MgSiO3_3-perovskite and MgSiO3_3-post-perovskite, the major phases of the Earth's lower mantle. We show that this first order correction is quite satisfactory for obtaining the aggregated elastic averages of these minerals and their velocities in the lower mantle. This type of correction is also shown to be applicable to experimental measurements of elastic constants in situations where deviatoric stresses can develop, such as in diamond anvil cells.Comment: 4 figures, 1 table, submitted to Phys. Rev. B, July 200

    Deterministic, Stash-Free Write-Only ORAM

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    Write-Only Oblivious RAM (WoORAM) protocols provide privacy by encrypting the contents of data and also hiding the pattern of write operations over that data. WoORAMs provide better privacy than plain encryption and better performance than more general ORAM schemes (which hide both writing and reading access patterns), and the write-oblivious setting has been applied to important applications of cloud storage synchronization and encrypted hidden volumes. In this paper, we introduce an entirely new technique for Write-Only ORAM, called DetWoORAM. Unlike previous solutions, DetWoORAM uses a deterministic, sequential writing pattern without the need for any "stashing" of blocks in local state when writes fail. Our protocol, while conceptually simple, provides substantial improvement over prior solutions, both asymptotically and experimentally. In particular, under typical settings the DetWoORAM writes only 2 blocks (sequentially) to backend memory for each block written to the device, which is optimal. We have implemented our solution using the BUSE (block device in user-space) module and tested DetWoORAM against both an encryption only baseline of dm-crypt and prior, randomized WoORAM solutions, measuring only a 3x-14x slowdown compared to an encryption-only baseline and around 6x-19x speedup compared to prior work

    Flight tests of IFR landing approach systems for helicopters

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    Joint NASA/FAA helicopter flight tests were conducted to investigate airborne radar approaches (ARA) and microwave landing system (MLS) approaches. Flight-test results were utilized to prove NASA with a data base to be used as a performance measure for advanced guidance and navigation concepts, and to provide FAA with data for establishment of TERPS criteria. The first flight-test investigation consisted of helicopter IFR approaches to offshore oil rigs in the Gulf of Mexico, using weather/mapping radar, operational pilots, and a Bell 212 helicopter. The second flight-test investigation consisted of IFR MLS approaches at Crows Landing (near Ames Research Center), with a Bell UH-1H helicopter, using NASA, FAA, and operational industry pilots. Tests are described and results discussed

    Influence of social status, physical activity, and socio-demographics on willingness to pay for a basket of organic foods

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    Consumers are known to signal social status through their purchasing behaviors. As the food industry continually expands its use of strategic marketing to reach customers, understanding food’s connection to this kind of status signaling may open the door to explore new markets for farmers. This study explored the influence of social status, physical activity, and socio-demographics on an individual’s willingness to pay for a basket of high-quality organic foods. Over 3 days, participants had their physical activity measured by a pedometer, and they were randomly assigned to a social status condition and subsequently placed bids for the organic food basket using a second-price auction to measure their willingness to pay. High-status individuals were publicly recognized in order to test our hypothesis that individuals will not be motivated to pay more for an organic food basket than low-status counterparts when they have already received recognition for their high status. The results showed that on average non-students were willing to pay significantly more for an organic food basket than student counterparts. Hispanic and Asian shoppers were willing to pay more for an organic food basket than White counterparts. However, physical activity had no significant impact on willingness to pay. Ultimately, our hypothesis was confirmed that recognizing high-status individuals eliminated or reduced the need to showcase social status through higher bids for the organic food baskets
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