From the view of Computer Science in general the toolbox that we have for the Semantic Web are a
bunch of standardized languages and
Knowledge Representations. There are also tools to use this information in the Web and as well as techniques how to get these representation Languages into the Web (e.g. RDFa, GRDDL, etc.).
Several problems in computer sciences are addressed by the problems that arise and are addressed by the Semantic Web.
Then of course there are Access restriction and. cryptography
Database technologies are also important, because the Knowledge Representation need to be stored in a persistent way. Traditional Databases (like Relational Databases) are not very well suited for this task.
Theoretical computer sciences are required because we need to trim and tune these algorithms to make them as stream lined as possible and it needs to be take into consideration the complexity of all that like runtime and storage complexity. Also Computer Architecture is involved as well as Software Engineering, Systems Theory and also in the end Computer Networks
Various fields of computer Science: