Tomasz Müldner, Gregory Leighton and Jan Krzysztof Miziołek
The purpose of this paper is to consider the secure publishing of XML documents, where a single copy of an XML document is disseminated and a stated role‐based access control…
Abstract
Purpose
The purpose of this paper is to consider the secure publishing of XML documents, where a single copy of an XML document is disseminated and a stated role‐based access control policy (RBACP) is enforced via selective encryption. It describes a more efficient solution over previously proposed approaches, in which both policy specification and key generation are performed once, at the schema‐level. In lieu of the commonly used super‐encryption technique, in which nodes residing in the intersection of multiple roles are encrypted with multiple keys, it describes a new approach called multi‐encryption that guarantees each node is encrypted at most once.
Design/methodology/approach
This paper describes two alternative algorithms for key generation and single‐pass algorithms for multi‐encrypting and decrypting a document. The solution typically results in a smaller number of keys being distributed to each user.
Findings
The paper proves the correctness of the presented algorithms, and provides experimental results indicating the superiority of multi‐encryption over super‐encryption, in terms of encryption and decryption time requirements. It also demonstrates the scalability of the approach as the size of the input document and complexity of the schema‐level RBACP are increased.
Research limitations/implications
An extension of this work involves designing and implementing re‐usability of keyrings when a schema or ACP is modified. In addition, more flexible solutions for handling cycles in schema graphs are possible. The current solution encounters difficulty when schema graphs are particularly deep and broad.
Practical implications
The experimental results indicate that the proposed approach is scalable, and is applicable to scenarios in which XML documents conforming to a common schema are to be securely published.
Originality/value
This paper contributes to the efficient implementation of secure XML publication systems.
Details
Keywords
Elhadi Shakshuki, Andreas Kerren and Tomasz Müldner
The purpose of this paper is to present the development of a system called Structured Hypermedia Algorithm Explanation (SHALEX), as a remedy for the limitations existing within…
Abstract
Purpose
The purpose of this paper is to present the development of a system called Structured Hypermedia Algorithm Explanation (SHALEX), as a remedy for the limitations existing within the current traditional algorithm animation (AA) systems. SHALEX provides several novel features, such as use of invariants, reflection of the high‐level structure of an algorithm rather than low‐level steps, and support for programming the algorithm in any procedural or object‐oriented programming language.
Design/methodology/approach
By defining the structure of an algorithm as a directed graph of abstractions, algorithms may be studied top‐down, bottom‐up, or using a mix of the two. In addition, SHALEX includes a learner model to provide spatial links, and to support evaluations and adaptations.
Findings
Evaluations of traditional AA systems designed to teach algorithms in higher education or in professional training show that such systems have not achieved many expectations of their developers. One reason for this failure is the lack of stimulating learning environments which support the learning process by providing features such as multiple levels of abstraction, support for hypermedia, and learner‐adapted visualizations. SHALEX supports these environments, and in addition provides persistent storage that can be used to analyze students' performance. In particular, this storage can be used to represent a student model that supports adaptive system behavior.
Research limitations/implications
SHALEX is being implemented and tested by the authors and a group of students. The tests performed so far have shown that SHALEX is a very useful tool. In the future additional quantitative evaluation is planned to compare SHALEX with other AA systems and/or the concept keyboard approach.
Practical implications
SHALEX has been implemented as a web‐based application using the client‐server architecture. Therefore students can use SHALEX to learn algorithms both through distance education and in the classroom setting.
Originality/value
This paper presents a novel algorithm explanation system for users who wish to learn algorithms.