Understanding Public-Key Infrastructure: Concepts, Standards, and Deployment Considerations

X.500

The ISO/ITU-T suite of standards for the directory, commonly known as the X.500 series of specifications [X.500], is the framework within which the X.509 document was originally created. The X.500 Directory is a highly sophisticated repository of arbitrary information and includes such features as client-to-directory access protocols, server-to-server communication protocols, full and partial replication of directory data, chaining of servers to respond to a query, complex search filtering capabilities, and so on. Recognition of the need for access control to the directory, including the requirement for strong authentication in some environments, led to the specification of certificate and CRL formats and other PKI concepts in the ...