Final answer:
A Certificate Authority (CA) is an organization that issues, manages, and revokes digital certificates playing a key role within the Public Key Infrastructure (PKI). CAs ensure secure communications by verifying and binding identities with public keys. This process helps in establishing secure connections over the internet.
Step-by-step explanation:
A Certificate Authority (CA) is an entity trusted by one or more users to manage certificates. When discussing a CA within the context of digital security and encryption, it refers to an organization that issues digital certificates. These certificates are used to verify the identity of entities such as websites, email accounts, and companies to ensure secure communication over the internet. Certificate Authorities are a crucial part of the Public Key Infrastructure (PKI), which is an arrangement that binds public keys with respective identities of entities.
The binding is established through the registration and issuance process carried out by the CA. The CA verifies the identity of the entity requesting the certificate, issues the certificate, and later, may also be involved in the revocation of certificates if necessary. It is important to note that a Registration Authority (RA) may also be part of the PKI, working in conjunction with the CA. The RA is responsible for accepting requests for digital certificates and authenticating the entity making the request before passing it to the CA for issuance.