A Description of Protocols for Private Credentials

This document provides a short description of practical protocols for private credential systems.1 We explain the basic concepts and mechanisms behind issuing and showing of private credentials and e-cash. The goal is to describe concisely how practical private credential systems can be achieved and not to provide intuition or motivation for the technology; for information on these subjects, see [1, 2, 3]. We give the details of one specific type of practical protocols for private credentials; other choices of functionalities and optimizations are possible. The reader is assumed to have general knowledge of basic concepts of cryptography such as the Discrete Logarithm problem, basic group theory and hash functions. For security proofs and more elaborate descriptions of the techniques used we refer the reader to [2].