(CA also stands for conditional access, a term used in DTV.) A
certificate authority (CA) is an authority in a network that
issues and manages security credentials and public keys for
message encryption. As part of a public key infrastructure
(PKI), a CA checks with a registration authority (RA) to verify
information provided by the requestor of a digital certificate.
If the RA verifies the requestor's information, the CA can then
issue a certificate. Depending on the public key infrastructure
implementation, the certificate includes the owner's public key,
the expiration date of the certificate, the owner's name, and
other information about the public key owner.