1,128 research outputs found

    Timed Analysis of Security Protocols

    Get PDF
    We propose a method for engineering security protocols that are aware of timing aspects. We study a simplified version of the well-known Needham Schroeder protocol and the complete Yahalom protocol, where timing information allows the study of different attack scenarios. We model check the protocols using UPPAAL. Further, a taxonomy is obtained by studying and categorising protocols from the well known Clark Jacob library and the Security Protocol Open Repository (SPORE) library. Finally, we present some new challenges and threats that arise when considering time in the analysis, by providing a novel protocol that uses time challenges and exposing a timing attack over an implementation of an existing security protocol

    A programming and a modelling perspective on the evaluation of Java card implementations

    Get PDF
    Java Card Technology has provided a huge step forward in programming smart cards: from assembler to using a high level Object Oriented language. However, the authors have found some differences between the current Java Card version (2.1) and main stream Java that may restrict the benefits of using Java achievable in smartcard programming. In particular, efforts towards evaluating Java Card implementations at a high level of assurance may be hampered by the presence of these differences as well as by the complexity of the Java Card VM and API. The goal of the present paper is to detail the differences from a programming and a modelling point of view

    Behavioral effects of thebaine in the rhesus monkey

    Full text link
    Three experiments were conducted with rhesus monkeys to assess some behavioral effects of the opium alkaloid, thebaine, in relation to its dependence liability. The concurrent intramuscular administration of naloxone did not antagonize the rate-decreasing effects of thebaine on a fixed-ratio (FR) schedule of food-reinforced responding. Animals trained to self-administer codeine (0.3 mg/kg/inj) on an FR 30 schedule did not self-administer thebaine (0.003-1.0 mg/kg/inj) at rates comparable to those of codeine. Rates were minimally above those of saline at 0.3 mg/kg/inj. Monkeys given 23 hrs/day continuous access to 1.0 mg/kg/inj thebaine did, however, self-administer the drug at rates significantly higher than those maintained by saline, but not as high as those supported by 2.0 mg/kg/inj codeine. Two animals self-administering thebaine did not show any signs of withdrawal when injected with 0.1-1.0 mg/kg of naloxone or when saline was substituted for thebaine. A third monkey showed a severe reaction leading to death following an injection of 1.0 mg/kg naloxone.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24370/1/0000639.pd

    Influence of Shear Flow on the Crystallization of Organic Melt Emulsions – A Rheo‐Nuclear Magnetic Resonance Investigation

    Get PDF
    There is a need to better understand the influence of shear flow on the crystallization of a molten oil phase in an oil/water emulsion due to its high relevance for industrial processes. The present study focuses on the influence of laminar shear flow on the crystallization kinetics of polydisperse n ‐hexadecane‐in‐water emulsions. The investigation was carried out by rheo‐nuclear magnetic resonance (NMR) spectroscopy in a Taylor‐Couette geometry. An accelerating impact of the shear rate on the overall crystallization kinetics was verified. This effect stems from an increase of the collision frequency of already crystallized droplets with not yet crystallized droplets. Nevertheless, the collision efficiency decreased with higher shear rate

    Optimization of the dark chocolate formulation from the mixture of cocoa beans and cocoa content by applying surface response method

    Get PDF
    This research sought to optimize the mix of Peruvian cocoa beans and the cocoa content for the dark chocolate formulation, having as an optimization criterion the improvement of the physical properties of chocolate: color, particle size, rheological properties and texture, applying the response surface methodology. It was found that the optimal formulation presented a mixture of cocoa beans of 10 parts of CCN 51 plus 90 parts of ICS 6, dark chocolate at 70 % cocoa content, 29.6 % sugar and 0.4 % lecithin. Finally, the validation of physical properties reached 91.6 % on average

    Verification of a Transactional Memory Manager under Hardware Failures and Restarts

    Full text link
    Abstract. We present our formal verification of the persistent mem-ory manager in IBM’s 4765 secure coprocessor. Its task is to achieve a transactional semantics of memory updates in the face of restarts and hardware failures and to provide resilience against the latter. The inclu-sion of hardware failures is novel in this area and incurs a significant jump in system complexity. We tackle the resulting verification challenge by a combination of a monad-based model, an abstraction that reduces the system’s non-determinism, and stepwise refinement. We propose novel proof rules for handling repeated restarts and nested metadata transac-tions. Our entire development is formalized in Isabelle/HOL.

    Ex Vivo

    Get PDF
    The measurement of vaccine-induced humoral and CD4+ and CD8+ cellular immune responses represents an important correlate of vaccine efficacy. Accurate and reliable assays evaluating such responses are therefore critical during the clinical development phase of vaccines. T cells play a pivotal role both in coordinating the adaptive and innate immune responses and as effectors. During the assessment of cell-mediated immunity (CMI) in subjects participating in a large-scale influenza vaccine trial, we identified the expansion of an IFN-γ-producing CD3+CD4-CD8-γδ+ T cell population in the peripheral blood of 90/610 (15%) healthy subjects. The appearance of CD3+CD4-CD8-γδ+ T cells in the blood of subjects was transient and found to be independent of the study cohort, vaccine group, subject gender and ethnicity, and ex vivo restimulation conditions. Although the function of this population and relevance to vaccination are unclear, their inclusion in the total vaccine-specific T-cell response has the potential to confound data interpretation. It is thus recommended that when evaluating the induction of IFN-γ-producing CD4+ and CD8+ immune responses following vaccination, the CD3+CD4-CD8-γδ+ T cells are either excluded or separately enumerated from the overall frequency determination
    corecore