Human-centred computer security

We re-examine the needs of computer security in pervasive computing from first principles, specifically the problem of bootstrapping secure networks. We consider the case of systems that may have no shared secret information, and where there is no structure such as a PKI available. Nevertheless we propose a protocol which achieves a high degree of security based on a combination of humanmediated communication and an ordinary Dolev-Yao communication medium. In particular it resists combinatorial attacks on the hash values that have to be compared by human users, seemingly optimising the amount of security they can achieve for a given amount of work. A variant of this protocol achieves one-sided authentication in a scenario similar to that of authenticating one or more bluetooth devices. We discuss the properties and verification of