Certifying Services in Cloud: The Case for a Hybrid, Incremental and Multi-layer Approach

The use of clouds raises significant security concerns for the services they provide. Addressing these concerns requires novel models of cloud service certification based on multiple forms of evidence including testing and monitoring data, and trusted computing proofs. CUMULUS is a novel infrastructure for realising such certification models

Security Attributes Based Digital Rights Management

Most real-life systems delegate responsibilities to different authorities. We apply this model to a digital rights management system, to achieve flexible security. In our model a hierarchy of authorities issues certificates that are linked by cryptographic means. This linkage establishes a chain of control, identity-attribute-rights, and allows flexible rights control over content. Typical security objectives, such as identification, authentication, authorization and access control can be realised. Content keys are personalised to detect illegal super distribution. We describe a working prototype, which we develop using standard techniques, such as standard certificates, XML and Java. We present experimental results to evaluate the scalability of the system. A formal analysis demonstrates that our design is able to detect a form of illegal super distribution

Low mass star formation and subclustering in the HII regions RCW 32, 33 and 27 of the Vela Molecular Ridge. A photometric diagnostics to identify M-type stars

Most stars born in clusters and recent results suggest that star formation (SF) preferentially occurs in subclusters. Studying the morphology and SF history of young clusters is crucial to understanding early SF. We identify the embedded clusters of young stellar objects (YSOs) down to M stars, in the HII regions RCW33, RCW32 and RCW27 of the Vela Molecular Ridge. Our aim is to characterise their properties, such as morphology and extent of the clusters in the three HII regions, derive stellar ages and the connection of the SF history with the environment. Through public photometric surveys such as Gaia, VPHAS, 2MASS and Spitzer/GLIMPSE, we identify YSOs with IR, Halpha and UV excesses, as signature of circumstellar disks and accretion. In addition, we implement a method to distinguish M dwarfs and giants, by comparing the reddening derived in several optical/IR color-color diagrams, assuming suitable theoretical models. Since this diagnostic is sensitive to stellar gravity, the procedure allows us to identify pre-main sequence stars. We find a large population of YSOs showing signatures of circumstellar disks with or without accretion. In addition, with the new technique of M-type star selection, we find a rich population of young M stars with a spatial distribution strongly correlated to the more massive population. We find evidence of three young clusters, with different morphology. In addition, we identify field stars falling in the same region, by securely classifying them as giants and foreground MS stars. We identify the embedded population of YSOs, down to about 0.1 Msun, associated with the HII regions RCW33, RCW32 and RCW27 and the clusters Vela T2, Cr197 and Vela T1, respectively, showing very different morphologies. Our results suggest a decreasing SF rate in Vela T2 and triggered SF in Cr197 and Vela T1.Comment: Accepted for publication in A&A; 20 pages, 22 figures, 6 table

Big Data Assurance Evaluation: An SLA-Based Approach.

The Big Data community has started noticing that there is the need to complete Big Data platforms with assurance techniques proving the correct behavior of Big Data analytics and management. In this paper, we propose a Big Data assurance solution based on Service-Level Agreements (SLAs), focusing on a platform providing Model-based Big Data Analytics-as-a-Service (MBDAaaS)

The Essex-Lopresti lesion

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Unveiling the Cygnus OB2 stellar population with Chandra

The aim of this work is to identify the so far unknown low mass stellar population of the ~2Myr old Cygnus OB2 region, and to investigate the X-ray and near-IR stellar properties of its members. We analyzed a 97.7 ksec Chandra ACIS-I observation pointed at the core of the Cygnus OB2 region. X-ray variability ans spectral analysis of sources was characterized through the KS-test and XSPEC thermal models, respectively. We detected 1003 X-ray sources. Of these, 775 have near-IR counterparts associated with Cygnus OB2 members. We estimate a typical absorption toward Cygnus OB2 of Av~7.0 mag. Although the region is young, very few stars (~4.4 %) show disk-induced excesses in the near-IR. X-ray variability is detected in ~13 % of the sources. Flares account for at least 60 % of the variability. O- that early B-type stars are not significantly variable. Typical X-ray spectral parameters are log(Nh)~22.25 and kT~1.35 keV. Variable and flaring sources have harder spectra with median kT=3.3 and 3.8 keV, respectively. OB stars are typically softer (kT~0.75 keV). X-ray luminosities range between 1E+30 and 1E+31 erg/s for intermediate- and low-mass stars, and 2.5x10^30 and between 6.3E+33 erg/s for OB stars. The Cygnus OB2 region has a very rich population of low-mass X-ray emitting stars. Circumstellar disks seem to be very scarce.Comment: Accepted for publication in A&A. 20 pages, 17 figure

Towards Transparent and Trustworthy Cloud

Despite its immense benefits in terms of flexibility, resource consumption, and simplified management, cloud computing raises several concerns due to lack of trust and transparency. Like all computing paradigms based on outsourcing, the use of cloud computing is largely a matter of trust. There is an increasing pressure by cloud customers for solutions that would increase their confidence that a cloud service/application is behaving in a secure and correct manner. Cloud assurance techniques, developed to assess the trustworthiness of cloud services, can play a major role in building trust. In this paper, we start from the assumption that an opaque cloud does not fit security, and present a reliable evidence collection process and infrastructure extending existing assurance techniques towards the definition of a trustworthy cloud. The proposed process and infrastructure are applied to a case study on cloud certification showing their utility