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replaced by automated ones, traditional forms of security such as photographs and handwritten signatures are becoming outdated.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 and software, 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...