Abstract—Sharing digital contents on the Web has become one of the most popular activities on the Internet. When the contents are sensitive in nature, sharing them online has security implications. Recently social relations are used extensively as access constraints to secure the content sharing. However only relation cannot provide personalized and granular enough access control. To mitigate the problems, this paper proposes an access authorization model incorporating diverse real life social relations and associated attributes such as trust, distance of relations and frequency of interactions. The model comprises of a formal knowledge base and personalized access authorization policies. We implement the model using the capabilities of sem...