terprise or organization through several ways and for several reasons, such as revenge from disgruntled employees. It can also occur through unauthorized access to privileged corporate information that can be used illegally to commit securities fraud, insider trading, and SO on. Whether it is file downloading between sites or files exchanged between workstations on the same local area network (LAN), whether it is electronic purchasing or bill payment where a person wants to guaran- tee the confidentiality of the session, or whether it is corporate e-mail (or, more recently, full-fledged telephone conversations and videoconferencing), users want to rely on security. However, confidentiality is only one aspect of the problem. Beyond matters of personal or corpo- rate security, communications security is also mandatory in ordinary contexts. Users have become more mobile over the last decade and want easy access anywhere and anytime to published, audio, and/or video content. Companies can only safely distribute this material from their servers if the requesting user can be properly authenticated as a legitimate user with an account in good standing. This overall context has therefore created a ubiquitous and ever-increasing need for communica- tions security through the encryption of the transmitted content and the authentication of the parties involved, whether individuals are talking over the telephone, software programs are running on dif- ferent computers that communicate with each other, or users are attempting to access a web site in order to carry out a legitimate electronic-purchase or payment transaction over the Internet. Controlled access to specific resources, confidentiality, the authentication of communicating par- ties, and the nonrepudiation of financial transactions are all based on structured and often industry- wide standardized use of cryptographic technologies. Robust cryptography in its multiple forms remains a set of heavily computation-intensive processes whose aggregate load only increases ex