Timed Analysis of Security Protocols

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

Varijacija i norma u hrvatskom crkvenoslavenskom

On the basis of A. Issatschenko\u27s definition of "literary language" and P. Rehder\u27s recent explication of that definition with the reference to medieval Croatia, the author concludes that Croatian Chruch Slavonic (CCS), neither by itself nor as part of a functional unity including also the čakavian dialect, texts composed in that dialect, and mixed čakavian-CCS text, could be characterized as a literary language. Medieval Croatian literacy was based on the coexistence of two independent sociolinguistic systems. One was the "Latinic complex", based on Latin-Čakavian bilingualism. Its most visible characteristics were the Latinic script and Latin liturgy. The second was the "Glagolitic complex", based on CCS-čakavian diglossia. The most visible features of this complex were the Glagolitic script and Slavonic liturgy. Croatian diglossia was probably of the type which the High and Low variants represent not only a functional, but also a linguistic unity. In the absence of explicit codification (grammatical-orthographical manuals and/or polemics concerning the linguistic norm), the norm was established and maintained through the example of the most authoritative texts. In such a situation, one genre (or group of genres) had to be set apart as an exemplary genre, in which infiltration of non-normative elements was not allowed. Stylistically motivated deviation from the norm in other genres would be conditioned by the establishment and documentation of the norm in the exemplary genre. The author suggests as a working hypothesis that the exemplary genre of CCS consisted of the biblical lections (i. e. lectionary) of the missal.Varijacija i norma u hrvatskom crkvenoslavenskom Na temelju Isačenkove definicije književnog jezika i Rehderova nedavna objašnjenja definicije u odnosu na srednjovjekovnu Hrvatsku, autor zaključuje da hrvatski crkvenoslavenski (HC), ni samostalno ni kao dio funkcionalnog jedinstva koje uključuje i čakavski dijalekt, ne može biti određen kao književni jezik. Srednjovjekovna hrvatska književnost temeljila se na supostojanju dvaju neovisnih sociolingvističkih sustava. Jedan je bio "latinski kompleks", koji se temeljio na latinsko-čakavskoj dvojezičnosti (bilingvizmu). Njegovo najočitije svojstvo bila je latinica i latinska liturgija. Drugi je "glagoljski kompleks", koji se temelji na HC-čakavskoj diglosiji. Najočitija svojstva toga kompleksa bila su glagoljica i slavenska liturgija. Hrvatska diglosija vjerojatno je takva u kojoj visoka i niska varijanta pokazuju ne samo funkcionalno već i lingvističko jedinstvo. U nedostatku eksplicitne kodifikacije (gramatičko-ortografski priručnik i/ili polemike o lingvističkoj normi) norma je uspostavljena i održavana na primjeru najautoritativnijih tekstova. U tom slučaju, jedan žanr (ili skupina žanrova) morao se istaknuti kao primjerni žanr u kojem infiltracija nenormativnih elemenata nije dopuštena. Stilistički motivirano odstupanje od norme u drugim žanrovima bilo bi uvjetovano uspostavom dokumentacije norme u primjernom žanru. Autor predlaže radnu hipotezu da se primjerni žanr HC sastojao od biblijskih lekcija (tj. lekcionara) iz misala

The Audit Logic: Policy Compliance in Distributed Systems

We present a distributed framework where agents can share data along with usage policies. We use an expressive policy language including conditions, obligations and delegation. Our framework also supports the possibility to refine policies. Policies are not enforced a-priori. Instead policy compliance is checked using an a-posteriri auditing approach. Policy compliance is shown by a (logical) proof that the authority can systematically check for validity. Tools for automatically checking and generating proofs are also part of the framework.\u

On the Localization of One-Photon States

Single photon states with arbitrarily fast asymptotic power-law fall-off of energy density and photodetection rate are explicitly constructed. This goes beyond the recently discovered tenth power-law of the Hellwarth-Nouchi photon which itself superseded the long-standing seventh power-law of the Amrein photon.Comment: 7 pages, tex, no figure

Automating Security Analysis: Symbolic Equivalence of Constraint Systems

We consider security properties of cryptographic protocols, that are either trace properties (such as confidentiality or authenticity) or equivalence properties (such as anonymity or strong secrecy). Infinite sets of possible traces are symbolically represented using deducibility constraints. We give a new algorithm that decides the trace equivalence for the traces that are represented using such constraints, in the case of signatures, symmetric and asymmetric encryptions. Our algorithm is implemented and performs well on typical benchmarks. This is the first implemented algorithm, deciding symbolic trace equivalence

Ultraviolet writing of channel waveguides in proton-exchanged LiNbO₃

We report on a direct ultraviolet (UV) writing method for the fabrication of channel waveguides at 1.55 µm in LiNbO3 through UV irradiation of surface and buried planar waveguides made by annealed proton exchange and reverse proton exchange. A systematic study of the guidance properties as a function of the UV writing conditions is presented

A two-way photonic interface for linking Sr+ transition at 422 nm to the telecommunications C-band

We report a single-stage bi-directional interface capable of linking Sr+ trapped ion qubits in a long-distance quantum network. Our interface converts photons between the Sr+ emission wavelength at 422 nm and the telecoms C-band to enable low-loss transmission over optical fiber. We have achieved both up- and down-conversion at the single photon level with efficiencies of 9.4% and 1.1% respectively. Furthermore we demonstrate noise levels that are low enough to allow for genuine quantum operation in the future.Comment: 5 pages, 4 figure

N-methyl-D-aspartate receptor- antibody encephalitis impairs maintenance of attention to items in working memory

NMDA receptors (NMDAR) may be crucial to working memory (WM). Computational models predict that they sustain neural firing and produce associative memory, which may underpin maintaining and binding information respectively. We test this in patients with antibodies to NMDAR (n=10, female) and compare them with healthy control participants (n=55, 20 male, 35 female). Patients were tested after recovery with a task that separates two aspects of WM: sustaining attention and feature binding. Participants had to remember two colored arrows. Then attention was directed to one of them. After a variable delay, they reported the direction of either the same arrow (congruent cue), or of the other arrow (incongruent cue). We asked how congruency affected recall precision and measured types of error. Patients had difficulty in both sustaining attention to an item over time and feature binding. Controls were less precise after longer delays and incongruent cues. In contrast, patients did not benefit from congruent cues at longer delays (Group x Congruency [long condition], p=0.041), indicating they could not sustain attention. Additionally, patients reported the wrong item (misbinding errors) more than controls after congruent cues (Group x Delay [congruent condition], main effect of group, p=Significance Statement Computational theories suggest NMDA receptors (NMDARs) are critical for actively maintaining information, while other theories propose they allow us to associate or "bind" objects features together. This is the first causal test in humans of the role of NMDARs in actively maintaining attention in working memory and feature binding. We find patients have difficulty with both these processes in support of computational models. Notably, we demonstrate that patients with NMDA receptor-antibody encephalitis are an ideal model condition to study roles of receptors in human cognition. Secondly, few studies follow these patients long after treatment. Our findings demonstrate a specific long-term neuropsychological deficit, previously unreported to our knowledge, that highlights the need for greater focus on neurocognitive rehabilitation with these patients

Verbal learning impairment in euthymic bipolar disorder: BDI v BDII

AbstractObjectivesCognitive impairment is known to occur in bipolar disorder (BD), even in euthymic patients, with largest effect sizes often seen in Verbal Learning and Memory Tasks (VLT). However, comparisons between BD Type-I and Type-II have produced inconsistent results partly due to low sample sizes.MethodsThis study compared the performance of 183 BDI with 96 BDII out-patients on an adapted version of the Rey Verbal Learning Task. Gender, age, years of education, mood scores and age at onset were all used as covariates. Current medication and a variety of illness variables were also investigated for potential effects on VLT performance.ResultsBDI patients were significantly impaired relative to BDII patients on all five VLT outcome measures after controlling for the other variables [Effect Sizes=.13–.17]. The impairments seem to be unrelated to drug treatment and largely unrelated to illness variables, although age of onset affected performance on three outcome measures and number of episodes of mood elevation affected performance on one.LimitationsThis study used historical healthy controls. Analysis of potential drug effects was limited by insufficient participants not being drug free. Cross-sectional nature of the study limited the analysis of the potential effect of illness variables.ConclusionsThis study replicates earlier findings of increased verbal learning impairment in BDI patients relative to BDII in a substantially larger sample. Such performance cannot be wholly explained by medication effects or illness variables. Thus, the cognitive impairment is likely to reflect a phenotypic difference between bipolar sub-types