Security functions for a file repository

When personal machines are incorporated into distributed\ud systems a new mixture of threats is exposed.\ud The security effort in the MobyDick project\ud is aimed at understanding how privacy can be protected\ud in this new environment. Our claim is that\ud a two-step process for authentication and authorisation\ud is required, but also sufficient. The research\ud vehicle is a distributed file repository

Large-signal charge control modeling of photoreceivers for applications up to 40 Gb/s

A charge control model was used to simulate the sensitivity and responsivity in a range of photodetector configurations including heterojunction bipolar phototransistors (HPTs), PIN-HBT, and APDs. Our simulations enabled for the first time a direct comparison of the performance between these photodetectors to be made. Simulations have been performed at bit rates from 2 to 40 Gb/s using various combinations of device design parameters (layer thickness, source resistance, and dc base voltage). For a BER = 10(-9) at 40 Gb/s the best sensitivity of approximately -20 dBm was achieved using an optimized APD-HBT configuration, followed by sensitivities of approximately -14 dBm using optimized PIN-HBTs and HPTs. These results were found to agree well with published experimental data

Detecting Key-Dependencies

The confidentiality of encrypted data depends on how well the key under which it was encrypted is maintained. If a session key was exchanged encrypted under a long-term key, exposure of the long-term key may reveal the session key and hence the data encrypted with it. The problem of key-dependencies between keys can be mapped onto connectivity of a graph, and the resulting graph can be inspected. This article presents a structured method (an algorithm) with which key-dependencies can be detected and analysed. Several well-known protocols are examined, and it is shown that they are vulnerable to certain attacks exploiting key-dependencies. Protocols which are free from this defect do exist. That is, when a session is terminated it is properly closed

The Implications of the EU-Turkey Refugee Agreement on the EU’s Role as an International Human Rights Actor

CESAA Essay Competition 2018 – Postgraduate winner: Katie HelmeWhile the European Union (EU) discursively frames itself as a values-driven actor, the recent influx of individuals seeking asylum within its borders problematises this image. The EU-Turkey refugee agreement, signed in March 2016, has been embraced as a mode to offset the burden of mass migration to the EU and to reassert the EU’s image as an international human rights actor. This paper contends, however, that the agreement negates the EU’s capacity to actively promote human rights norms externally by: 1) compromising on its high standards in order to achieve internal cohesion and redress waning solidarity between member states; 2) transgressing EU and international laws and norms; and 3) relegating the previous approach it has taken to seeking structural reform in Turkey. Ultimately, this paper concludes that the EU’s participation in the refugee agreement with Turkey delegitimises the EU as an international human rights actor

Torsion in Graph Homology

Khovanov homology for knots has generated a flurry of activity in the topology community. This paper studies the Khovanov type cohomology for graphs with a special attention to torsions. When the underlying algebra is $\mathbb{Z}[x]/(x^2)$, we determine precisely those graphs whose cohomology contains torsion. For a larger class of algebras, we show that torsion often occurs. Our investigation of torsion led to other related general results. The ideas of this paper could potentially be used to predict the Khovanov-Rozansky $sl(m)$ homology of knots (in particular $(2,n)$ torus knots). We also predict that our work is connected with Hochschild and Connes cyclic homology of algebras.Comment: 45 pages, 20 figures, Fundamenta Mathematicae, 190, 2006, to appea