One-time capabilities for authorizations without trust

This paper introduces and solves a security problem of pervasive computing: how to define authorizations for off-line interactions when trust relationships among entities do not exist. A new type of capability is proposed to assure that user interactions are not traceable and that misbehaving users automatically lose some money they deposited as a guarantee of their loyalty. The solution inspired by electronic cash is based on a new version of the cut-and-choose protocol adapted for open environments.