|Burnap, Peter 2009. Advanced access control in support and distributed collaborative working and de-perimeterization. PhD Thesis, Cardiff University.|
- Accepted Post-Print Version
This thesis addresses the problem of achieving fine-grained and sustained control of access to electronic information, shared in distributed collaborative environments. It presents an enhanced approach to distributed information security architecture, driven by the risks, guidelines and legislation emerging due to the growth of collaborative working, and the often associated increase in storage of information outside of a secured information system perimeter. Traditional approaches to access control are based on applying controls at or within the network perimeter of an information system. One issue with this approach when applying it to shared information is that, outside of the perimeterized zone, the owner loses control of their information. This loss of control could dissuade collaborating parties from sharing their information resources. Information resources can be thought of as a collection of related content stored in a container. Another issue with current approaches to access control, particularly to unstructured resources such as text documents, is the coarse granularity of control they provide. That is, controls can only apply to a resource in its entirety. In reality, the content within a resource could have varying levels of security requirements with different levels of control. For example, some of the content may be completely free from any access restriction, while other parts may be too sensitive to share outside of an internal organisation. The consequence being that the entire resource is restricted with the controls relevant to the highest level content. Subsequently, a substantial amount of information that could feasibly be shared in collaborative environments is prevented from being shared, due to being part of a highly restricted resource. The primary focus of this thesis is to address these two issues by investigating the appropriateness and capability of perimeter security, and entire-resource protection, to provide access control for information shared in collaborative distributed environments. To overcome these problems, the thesis develops an access control framework, based on which, several formulae are defined to clarify the problems, and to allow them to be contextualised. The formulae have then been developed and improved, with the problem in mind, to create a potential solution, which has been implemented and tested to demonstrate that it is possible to enhance access control technology to implement the capability to drill down into the content of an information resource and apply more fine-grained controls, based on the security requirements of the content within. Furthermore, it is established that it is possible to shift part of the controls that protect information resources within a secure network perimeter, to the body of the resources themselves so that they become, to some extent, self protecting. This enables the same controls to be enforced outside of the secure perimeter. The implementation is based on the structuring of information and embedding of metadata within the body of an information resource. The metadata effectively wraps sections of content within a resource into containers that define fine-grained levels of access control requirement, to protect its confidentiality and integrity. Examples of the granularity afforded by this approach could be page, paragraph, line or even word level in a text document. Once metadata has been embedded, it is bound to a centrally controlled access control policy for the lifetime of the resource. Information can then be shared, copied, distributed and accessed in support of collaborative working, but a link between the metadata and the centrally controlled policy is sustained, meaning that previously assigned access privileges to different sections of content can be modified or revoked at any time in the future. The result of this research is to allow information sharing to reach a greater level of acceptance and usage due to: i. the enhanced level of access control made possible through finer-grained controls, allowing the content of a single resource to be classified and restricted at different levels, and ii. the ability to retain sustained control over information through modifiable controls, that can be enforced both while the information is stored on local information systems, and after the information has been shared outside the local environment.
|Item Type:||Thesis (PhD)|
|Schools:||Computer Science & Informatics|
|Subjects:||Q Science > QA Mathematics > QA75 Electronic computers. Computer science|
|Last Modified:||19 Dec 2014 11:23|
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