Abstract :
Security protocols form a central part of the trust infrastructure of the online world. They allow principals to make decisions that authorize or prohibit actions of other principals, and to make those decisions based on information gathered from other principals. In this invited talk at Socio-Technical Aspects in Security and Trust 2012 (STAST), a view of protocol design that can serve as a trust infrastructure is described. “Trust engineering” is a process leading to protocols that reflect participants´ concerns for authentication, confidentiality, controlling commitments, and repudiability or its opposite.