As paper-based communication and transaction mechanisms are replaced by automated ones, traditional forms of security such as photographs and handwritten signatures are becoming outdated. Most security experts believe that digital certificates offer the best technology for safeguarding electronic communications. They are already widely used for authenticating and encrypting email andsoftware, and eventually will be built into any device or piece of software that must be able to communicate securely. There is a serious problem, however, with this unavoidable trend: unless drastic measures are taken, everyone will be forced to communicate via what will be the most pervasive electronic surveillance tool ever built. There will also be abundant opportunity for misuse of digital certificates by hackers, unscrupulous employees, government agencies, financial institutions, insurance companies, and so on. In his recently published book (MIT Press), Stefan Brands proposes cryptographic building blocks for the design of digital certificates that preserve privacy without sacrificing security. Such certificates function in much the same way as cinema tickets or subway tokens: anyone can establish their validity and the data they specify, but no more than that. Furthermore, different actions by the same person cannot be linked. Certificate holders have control over what information is disclosed, and to whom. Subsets of the proposed cryptographic building blocks can be used in combination, allowing a cookbook approach to the design of public key infrastructures. Potential applications include electronic cash, electronic postage, digital rights management, pseudonyms for online chat rooms, health care information storage, electronic voting, and even electronic gambling. Dr. Stefan Brands is a leading cryptographer who specializes in building privacy-protecting PKIs, digital identity authentication systems and electronic cash. He earned his Ph.D. from the Technical University of Eindhoven for his thesis "Rethinking Public Key Infrastructures and Digital Certificates -- Building in Privacy." The committee that awarded him his doctorate included threeof the world's top cryptographers: Adi Shamir (Weizmann Institute of Science) and Ronald L. Rivest (Massachusetts Institute of Technology) and Claus Schnorr (University of Frankfurt am Main). Also, DigiCash had planned to implement his electronic cash technologies as the successor to their own e-cash system. The electronic cash system he published in 1993 (and subsequently extended and improved) forms the core of a full-fledged system implemented and tested by CAFE, an ESPRIT project with 13 academic and commercial member organizations from seven European countries. Dr. Brands is the owner of eight international patents on electronic cash and digital certificates.