Name-passing calculi and crypto-primitives: A survey

The paper surveys the literature on high-level name-passing process calculi, and their extensions with cryptographic primitives. The survey is by no means exhaustive, for essentially two reasons. First, in trying to provide a coherent presentation of different ideas and techniques, one inevitably ends up leaving out the approaches that do not fit the intended roadmap. Secondly, the literature on the subject has been growing at very high rate over the years. As a consequence, we decided to concentrate on few papers that introduce the main ideas, in the hope that discussing them in some detail will provide sufficient insight for further reading

Channel Abstractions for Network Security

Process algebraic techniques for distributed systems are increasingly being targeted at identifying abstractions adequate both for high-level programming and specification, and for security analysis and verification. Drawing on our earlier work in [Bugliesi & Focardi 2008] F08}, we investigate the expressive power of a core set of security and network abstractions that provide high-level primitives for the specifications of the honest principals in a network, while at the same time enabling an analysis of the network-level adversarial attacks that may be mounted by an intruder. We analyze various bisimulation equivalences for security, arising from endowing the intruder with (i) different adversarial capabilities and (ii) increasingly powerful control on the interaction among the distributed principals of a network. By comparing the relative strength of the bisimulation equivalences, we obtain a direct measure of the discriminating power of the intruder, hence of the expressiveness of the corresponding intruder model

Optical properties of the NGC 5328 group of galaxies

We present the results of a photometric and spectroscopic study of seven members of the NGC 5328 group of galaxies, a chain of galaxies spanning over 200 kpc (H_0 = 70 km/s/Mpc). We analyze the galaxy structure and study the emission line properties of the group members looking for signatures of star formation and AGN activity. We finally attempt to infer, from the modeling of line-strength indices, the stellar population ages of the early-type members. We investigate also the presence of a dwarf galaxy population associated with the bright members. The group is composed of a large fraction of early-type galaxies including NGC 5328 and NGC 5330, two bona fide ellipticals at the center of the group. In both galaxies no recent star formation episodes are detected by the H_beta vs. MgFe indices of these galaxies. 2MASX J13524838-2829584 has extremely boxy isophotes which are believed to be connected to a merging event: line strength indices suggest that this object probably had a recent star formation episode. A warped disc component emerges from the model subtracted image of 2MASX J13530016-2827061 which is interpreted as a signature of an ongoing interaction with the rest of the group. Ongoing star formation and nuclear activity is present in the projected outskirts of the group. The two early-type galaxies 2MASX J13523852-2830444 and 2MASX J13525393-2831421 show spectral signatures of star formation, while a Seyfert 2 type nuclear activity is detected in MCG -5-33-29.Comment: 18 pages, 12 figures, accepted for publication in MNRA

Secrecy in Security Protocols as Non Interference

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Elektromagnetski model terahercnog mješala s dvostrukom proreznom antenom

Twin slot antennas coupled to superconducting devices are currently being developed for terahertz mixers and direct detectors for astronomical observations. Although these mixers show promising performance in terms of noise temperature, they usually also show a considerable downward shift in the center frequency, especially when compared with calculations obtained with commonly used simplified models. This discrepancy is actually due to a variety of reasons. The effect of the bolometer-to-CPW transition, the RF choke filter and the radiation losses in the CPW line have been demonstrated in a recent study to be some of the most important reasons of the disagreement between calculations and measurements. In this paper we discuss these effects and other features, such as the silicon lens, obtaining a more robust model suitable not only for analysis but also for the synthesis of these circuits. A complete set of terahertz mixers at four different center frequencies, between 600 GHz and 2.5 THz, has been fabricated following the guidelines provided by our model and is currently being tested. The preliminary results of power coupling measured at 2.5 THz are still not as good as expected, however they show that our model is going in the right direction. With respect to previous designs, the new mixers have now a much better efficiency in terms of power coupling to the superconducting device and the center frequency shift is now decreased roughly from 30 % to 10 %.Dvostruka prorezna antena u koju su ugrađeni supravodljivi elektronički elementi trenutačno se razvija za terahercna mješala i detekore za primjenu u astronomskim promatranjima. Iako ta mješala imaju nisku temperaturu šuma, redovito se javlja značajan pomak središnje frekvencije na niže vrijednosti u usporebi s rezultatima proračuna dobivenih uobičajenim pojednostavljenim modelima. Ovo je odstupanje frekvencije posljedica više uzroka. Najnovija su istraživanja pokazala da su najvažniji uzroci ovog odstupanja prijelaz između bolometra i koplanarne prijenosne linije, filtar za potiskivanje radiofrekvencijskog signala i gubici zbog zračenja koplanarne linije. U ovom se radu razmatraju ovi uzroci te novi elementi, kao što je silicijska leća, da bi se dobio robustniji model pogodan ne samo za analizu već i za sintezu ovih sklopova. Koristeći ovaj model izrađeno je i ispitano više terahercnih mješala na četiri različite središnje frekvencije između 600 GHz i 2,5 THz. Preliminarni rezulati prijenosa snage na 2,5 THz još uvijek nisu u potpunosti zadovoljavajući, ali pokazuju da je predloženi model postavio dobre smjernice. U usporedbi s ranijim izvedbama, nova mješala imaju mnogo bolju djelotvornost prijenosa snage u supravodljive elektroničke elemente, a pomak središnje frekvencije se smanjio s 30 % na 10 %

Elektromagnetski model terahercnog mješala s dvostrukom proreznom antenom

Twin slot antennas coupled to superconducting devices are currently being developed for terahertz mixers and direct detectors for astronomical observations. Although these mixers show promising performance in terms of noise temperature, they usually also show a considerable downward shift in the center frequency, especially when compared with calculations obtained with commonly used simplified models. This discrepancy is actually due to a variety of reasons. The effect of the bolometer-to-CPW transition, the RF choke filter and the radiation losses in the CPW line have been demonstrated in a recent study to be some of the most important reasons of the disagreement between calculations and measurements. In this paper we discuss these effects and other features, such as the silicon lens, obtaining a more robust model suitable not only for analysis but also for the synthesis of these circuits. A complete set of terahertz mixers at four different center frequencies, between 600 GHz and 2.5 THz, has been fabricated following the guidelines provided by our model and is currently being tested. The preliminary results of power coupling measured at 2.5 THz are still not as good as expected, however they show that our model is going in the right direction. With respect to previous designs, the new mixers have now a much better efficiency in terms of power coupling to the superconducting device and the center frequency shift is now decreased roughly from 30 % to 10 %.Dvostruka prorezna antena u koju su ugrađeni supravodljivi elektronički elementi trenutačno se razvija za terahercna mješala i detekore za primjenu u astronomskim promatranjima. Iako ta mješala imaju nisku temperaturu šuma, redovito se javlja značajan pomak središnje frekvencije na niže vrijednosti u usporebi s rezultatima proračuna dobivenih uobičajenim pojednostavljenim modelima. Ovo je odstupanje frekvencije posljedica više uzroka. Najnovija su istraživanja pokazala da su najvažniji uzroci ovog odstupanja prijelaz između bolometra i koplanarne prijenosne linije, filtar za potiskivanje radiofrekvencijskog signala i gubici zbog zračenja koplanarne linije. U ovom se radu razmatraju ovi uzroci te novi elementi, kao što je silicijska leća, da bi se dobio robustniji model pogodan ne samo za analizu već i za sintezu ovih sklopova. Koristeći ovaj model izrađeno je i ispitano više terahercnih mješala na četiri različite središnje frekvencije između 600 GHz i 2,5 THz. Preliminarni rezulati prijenosa snage na 2,5 THz još uvijek nisu u potpunosti zadovoljavajući, ali pokazuju da je predloženi model postavio dobre smjernice. U usporedbi s ranijim izvedbama, nova mješala imaju mnogo bolju djelotvornost prijenosa snage u supravodljive elektroničke elemente, a pomak središnje frekvencije se smanjio s 30 % na 10 %

Epoxy/ graphene nanocomposites – processing and properties: a review

Graphene has recently attracted significant academic and industrial interest because of its excellent performance in mechanical, electrical and thermal applications. Graphene can significantly improve physical properties of epoxy at extremely small loading when incorporated appropriately. Herein, the structure, preparation and properties of epoxy/graphene nanocomposites are reviewed in general, along with detailed examples drawn from the key scientific literature. The modification of graphene and the utilization of these materials in the fabrication of nanocomposites with different processing methods have been explored. This review has been focused on the processing methods and mechanical, electrical, thermal, and fire retardant properties of the nanocomposites. The synergic effects of graphene and other fillers in epoxy matrix have been summarised as well

A Semantic Hierarchy for Erasure Policies

We consider the problem of logical data erasure, contrasting with physical erasure in the same way that end-to-end information flow control contrasts with access control. We present a semantic hierarchy for erasure policies, using a possibilistic knowledge-based semantics to define policy satisfaction such that there is an intuitively clear upper bound on what information an erasure policy permits to be retained. Our hierarchy allows a rich class of erasure policies to be expressed, taking account of the power of the attacker, how much information may be retained, and under what conditions it may be retained. While our main aim is to specify erasure policies, the semantic framework allows quite general information-flow policies to be formulated for a variety of semantic notions of secrecy.Comment: 18 pages, ICISS 201

A hard lesson: Assessing the HTTPS deployment of Italian university websites

In this paper we carry out a systematic analysis of the state of the HTTPS deployment of the most popular Italian university websites. Our analysis focuses on three different key aspects: HTTPS adoption and activation, HTTPS certificates, and cryptographic TLS implementations. Our investigation shows that the current state of the HTTPS deployment is unsatisfactory, yet it is possible to significantly improve the level of security by working exclusively at the web application layer. We hope this observation will encourage site operators to take actions to improve the current state of protection