<P> A public key infrastructure (PKI) is a system for the creation, storage, and distribution of digital certificates which are used to verify that a particular public key belongs to a certain entity . The PKI creates digital certificates which map public keys to entities, securely stores these certificates in a central repository and revokes them if needed . </P> <P> A PKI consists of: </P> <Ul> <Li> A certificate authority (CA) that stores, issues and signs the digital certificates </Li> <Li> A registration authority which verifies the identity of entities requesting their digital certificates to be stored at the CA </Li> <Li> A central directory--i.e., a secure location in which to store and index keys </Li> <Li> A certificate management system managing things like the access to stored certificates or the delivery of the certificates to be issued . </Li> <Li> A certificate policy stating the PKI's requirements concerning its procedures . Its purpose is to allow outsiders to analyze the PKI's trustworthiness . </Li> </Ul> <Li> A certificate authority (CA) that stores, issues and signs the digital certificates </Li>

9. what are the components of pki