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

Certificates

Kohnfelder first introduced the concept of using a signed data structure or certificate to convey the public key to a relying party in his 1978 bachelor's thesis entitled "Towards a Practical Public-Key Cryptosystem" [Kohnfelder]. Thus, even two decades ago, it was recognized that a scalable and secure method (from an integrity perspective) would be required to convey the public keys to the parties that needed them. Simply stated, public-key certificates are used to bind an entity's name (and possibly additional attributes associated with that entity) with the corresponding public key.

When discussing the concept of a "certificate," it is important to recognize that a number of different types of certificates exist, including

• X.509 ...