A PKI (public key infrastructure) enables users of a basically unsecure public network such as the Internet to securely and privately exchange data and money through the use of a public and a private cryptographic key pair that is obtained and shared through a trusted authority. The public key infrastructure provides for a digital certificate that can identify an individual or an organization and directory services that can store and, when necessary, revoke the certificates. A public key infrastructure consists of: * A certificate authority (CA) that issues and verifies digital certificate. A digital certificate includes the public key or information about the public key * A registration authority (RA) that acts as the verifier for the certificate authority before a digital certificate is issued to a requestor * One or more directories where the certificates (with their public keys) are held * A certificate management system In public key cryptography, a public and private key are created simultaneously using the same algorithm (a popular one is known as RSA) by a certificate authority (CA). The private key is given only to the requesting party and the public key is made publicly available (as part of a digital certificate) in a directory that all parties can access. The private key is never shared with anyone or sent across the Internet. You use the private key to decrypt text that has been encrypted with your public key by someone else (who can find out what your public key is from a public directory.
