2,601 research outputs found
Cloud services, interoperability and analytics within a ROLE-enabled personal learning environment
The ROLE project (Responsive Open Learning Environments, EU 7th Framework Programme, grant agreement no.: 231396, 2009-2013) was focused on the next generation of Personal Learning Environments (PLEs). A ROLE PLE is a bundle of interoperating widgets - often realised as cloud services - used for teaching and learning. In this paper, we first describe the creation of new ROLE widgets and widget bundles at Galileo University, Guatemala, within a cloud-based infrastructure. We introduce an initial architecture for cloud interoperability services including the means for collecting interaction data as needed for learning analytics. Furthermore, we describe the newly implemented widgets, namely a social networking tool, a mind-mapping tool and an online document editor, as well as the modification of existing widgets. The newly created and modified widgets have been combined in two different bundles that have been evaluated in two web-based courses at Galileo University, with participants from three different Latin-American countries. We measured emotional aspects, motivation, usability and attitudes towards the environment. The results demonstrated the readiness of cloud-based education solutions, and how ROLE can bring together such an environment from a PLE perspective
Fair Exchange in Strand Spaces
Many cryptographic protocols are intended to coordinate state changes among
principals. Exchange protocols coordinate delivery of new values to the
participants, e.g. additions to the set of values they possess. An exchange
protocol is fair if it ensures that delivery of new values is balanced: If one
participant obtains a new possession via the protocol, then all other
participants will, too. Fair exchange requires progress assumptions, unlike
some other protocol properties. The strand space model is a framework for
design and verification of cryptographic protocols. A strand is a local
behavior of a single principal in a single session of a protocol. A bundle is a
partially ordered global execution built from protocol strands and adversary
activities. The strand space model needs two additions for fair exchange
protocols. First, we regard the state as a multiset of facts, and we allow
strands to cause changes in this state via multiset rewriting. Second, progress
assumptions stipulate that some channels are resilient-and guaranteed to
deliver messages-and some principals are assumed not to stop at certain
critical steps. This method leads to proofs of correctness that cleanly
separate protocol properties, such as authentication and confidentiality, from
invariants governing state evolution. G. Wang's recent fair exchange protocol
illustrates the approach
Relating Strand Spaces and Distributed Temporal Logic for Security Protocol Analysis
In previous work, we introduced a version of distributed temporal logic that is well-suited both for verifying security protocols and as a metalogic for reasoning about, and relating, different security protocol models. In this paper, we formally investigate the relationship between our approach and strand spaces, which is one of the most successful and widespread formalisms for analyzing security protocols. We define translations between models in our logic and strand-space models of security protocols, and we compare the results obtained with respect to the level of abstraction that is inherent in each of the formalisms. This allows us to clarify different aspects of strand spaces that are often left implicit, as well as pave the way to transfer results, techniques and tools across the two approache
A Trace Logic for Local Security Properties
We propose a new simple \emph{trace} logic that can be used to specify
\emph{local security properties}, i.e. security properties that refer to a
single participant of the protocol specification. Our technique allows a
protocol designer to provide a formal specification of the desired security
properties, and integrate it naturally into the design process of cryptographic
protocols. Furthermore, the logic can be used for formal verification. We
illustrate the utility of our technique by exposing new attacks on the well
studied protocol TMN.Comment: New versio
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