Public Key Infrastructure (PKI)

A Public Key Infrastructure (PKI) is a system of facilities, policies, and services that supports the use of public key cryptography for authenticating the parties involved in a transaction.

There is no single standard that defines the components of a Public Key Infrastructure, but a PKI typically comprises certificate authorities (CAs) and Registration Authorities (RAs). CAs provide the following services::
  • Issuing digital certificates
  • Validating digital certificates
  • Revoking digital certificates
  • Distributing public keys
The X.509 standards provide the basis for the industry standard Public Key Infrastructure.

Refer to Digital certificates for more information about digital certificates and certificate authorities (CAs). RAs verify the information provided when digital certificates are requested. If the RA verifies that information, the CA can issue a digital certificate to the requester.

A PKI might also provide tools for managing digital certificates and public keys. A PKI is sometimes described as a trust hierarchy for managing digital certificates, but most definitions include additional services. Some definitions include encryption and digital signature services, but these services are not essential to the operation of a PKI.