52 research outputs found

    Cryptanalysis of the RSA-CEGD protocol

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    Recently, Nenadi\'c et al. (2004) proposed the RSA-CEGD protocol for certified delivery of e-goods. This is a relatively complex scheme based on verifiable and recoverable encrypted signatures (VRES) to guarantee properties such as strong fairness and non-repudiation, among others. In this paper, we demonstrate how this protocol cannot achieve fairness by presenting a severe attack and also pointing out some other weaknesses.Comment: 8 pages, 1 figur

    SoNeUCONADM: the administrative model for SoNeUCONABC usage control model

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    The popularity of Web Based Social Networks (WBSNs) encourages their enhancement. Many WBSN data is considered personal data and access control management plays a key role in this regard. The point is not only to manage access control but to determine how administration should be performed. Based on SoNeUCONABC, an expressive usage control model that allows fine-grained access control management, this paper presents SoNeUCONADM, the complementary administrative model. Based on a pair of related and popular administrative models, the evaluation proves the completeness of SoNeUCONADM

    Steganalysis of Hydan

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    Hydan is a steganographic tool which can be used to hide any kind of information inside executable files. In this work, we present an efficient distinguisher for it: We have developed a system that is able to detect executable files with embedded information through Hydan. Our system uses statistical analysis of instruction set distribution to distinguish between files with no hidden information and files that have been modified with Hydan. We have tested our algorithm against a mix of clean and stego-executable files. The proposed distinguisher is able to tell apart these files with a 0 ratio of false positives and negatives, thus detecting all files with hidden information through Hydan

    Enantiopure double ortho-oligophenylethynylene-based helical structures with circularly polarized luminescence activity

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    In this paper, we describe the optical and chiroptical properties of an enantiopure multipodal ortho-oligophenylethynylene (S,S,S,S)-1 presenting four chiral sulfoxide groups at the extremes. The presence of these groups together with alkynes allows the coordination with carbophilic Ag(I), and/or oxophilic Zn(II) cations, yielding double helical structures in an enantiopure way. In this sense, different behaviors in absorption, fluorescence, ECD and CPL spectra have been found depending on the stoichiometry and nature of the metal. We have observed that Zn(II) coordination favors an intensity increase of the electronic circular dichroism (ECD) spectra of compound (S,S,S,S)-1 yielding an M-helicity in the ortho-oligophenylene ethynylene (o-OPE) backbone. On the other hand, ECD spectra of final Ag(I) complex shows two different bands with an opposite sign to the free ligand, thus giving the P-helical isomer. In addition, circularly polarized luminescence (CPL) exhibit an enhanced intensity and negative sign in both complexes. Computational studies were also carried out, supporting the experimental result

    Novel ortho-OPE metallofoldamers: binding-induced folding promoted by nucleating Ag(i)-alkyne interactions

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    We have developed a new family of ortho-oligophenylene ethynylene (o-OPE) metallofoldamers. The folding of these helicates is induced by nucleating carbon-metal interactions between Ag(i) cations and the alkynes of the inner core of the o-OPEs. These o-OPEs form metal-organic assemblies where at least three alkyne moieties are held in close proximity to form novel Ag(i)-complexes with the metal ion lodged into the helical cavity. NMR titration experiments and photokinetic studies have provided quantitative data about the thermodynamic and kinetic features of such binding/folding phenomena. X-ray diffraction and DFT studies have been performed to extract structural information on how the Ag(i) cation is accommodated into the cavity. The great simplicity and versatility of these new metallofoldamers open up the possibility to develop novel structures with applications in material science and/or in asymmetric catalysisThis research was funded by the Regional Government of Andalucía (project P09-FQM-4571) and the ICIQ Foundation. DM thanks Regional Government of Andalucía for her contract. AML thanks MICINN for her FPU fellowship. The authors thank the Centro de Servicios de Informática y Redes de Comunicaciones (CSIRC), Universidad de Granada, for providing the computing tim

    RICORS2040 : The need for collaborative research in chronic kidney disease

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    Chronic kidney disease (CKD) is a silent and poorly known killer. The current concept of CKD is relatively young and uptake by the public, physicians and health authorities is not widespread. Physicians still confuse CKD with chronic kidney insufficiency or failure. For the wider public and health authorities, CKD evokes kidney replacement therapy (KRT). In Spain, the prevalence of KRT is 0.13%. Thus health authorities may consider CKD a non-issue: very few persons eventually need KRT and, for those in whom kidneys fail, the problem is 'solved' by dialysis or kidney transplantation. However, KRT is the tip of the iceberg in the burden of CKD. The main burden of CKD is accelerated ageing and premature death. The cut-off points for kidney function and kidney damage indexes that define CKD also mark an increased risk for all-cause premature death. CKD is the most prevalent risk factor for lethal coronavirus disease 2019 (COVID-19) and the factor that most increases the risk of death in COVID-19, after old age. Men and women undergoing KRT still have an annual mortality that is 10- to 100-fold higher than similar-age peers, and life expectancy is shortened by ~40 years for young persons on dialysis and by 15 years for young persons with a functioning kidney graft. CKD is expected to become the fifth greatest global cause of death by 2040 and the second greatest cause of death in Spain before the end of the century, a time when one in four Spaniards will have CKD. However, by 2022, CKD will become the only top-15 global predicted cause of death that is not supported by a dedicated well-funded Centres for Biomedical Research (CIBER) network structure in Spain. Realizing the underestimation of the CKD burden of disease by health authorities, the Decade of the Kidney initiative for 2020-2030 was launched by the American Association of Kidney Patients and the European Kidney Health Alliance. Leading Spanish kidney researchers grouped in the kidney collaborative research network Red de Investigación Renal have now applied for the Redes de Investigación Cooperativa Orientadas a Resultados en Salud (RICORS) call for collaborative research in Spain with the support of the Spanish Society of Nephrology, Federación Nacional de Asociaciones para la Lucha Contra las Enfermedades del Riñón and ONT: RICORS2040 aims to prevent the dire predictions for the global 2040 burden of CKD from becoming true

    Anodic Oxidation of N-

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