Protocols are inductively defined as sets of traces. A trace is a list of communication events, perhaps comprising many interleaved protocol runs. Protocol descriptions incorporate attacks and accidental losses. The model spy knows some private keys and can forge messages using components decrypted from previous traffic. LC Paulson, Inductive Analysis of the Internet Protocol TLS , Technical Report 440, December 1997.
Internet browsers use security protocols to protect confidential messages.
Proofs are based on higher-order logic and make no assumptions concerning beliefs or finiteness. The analysis suggests modest changes to simplify the protocol. TLS, even at an abstract level, is much more complicated than most protocols that researchers have verified. Session keys are negotiated rather than distributed, and the protocol has many optional parts. Nevertheless, the resources needed to verify TLS are modest.