Affiliations: Department of Computer Science, University of Oxford, Wolfson Building, Parks Road, Oxford, OX1 3QD, UK. E-mails: [email protected], [email protected]
Abstract: In this paper, we analyse the Transport Layer Security (TLS) protocol (in particular, bilateral TLS in public-key mode) within the strand spaces setting. In Proceedings of the 16th IEEE Computer Security Foundations Workshop (CSFW), IEEE Computer Society, 2003, pp. 141–154, Broadfoot and Lowe suggested an abstraction of TLS. The abstraction models the security services that appear to be provided by the protocol to the high-level security layers. The outcome of our analysis provides a formalisation of the security services provided by TLS and proves that, under reasonable assumptions, the abstract model suggested by Broadfoot and Lowe is correct. To that end, we reduce the complexity of the protocol using fault-preserving simplifying transformations. We extend the strand spaces model in order to include the cryptographic operations used in TLS and facilitate its analysis. Finally, we use the extended strand spaces model to fully analyse the public-key mode of bilateral TLS with its two main components: the Handshake and Record Layer protocols.
Keywords: Transport Layer Security (TLS) protocol, formal analysis, strand spaces
