Analysing TLS in the strand spaces model

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 [BL03] 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 faultpreserving 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.