What is a Subscriber in the context of PKI?

• A. A type of hardware device
• B. An entity whose name appears on a certificate
• C. A person who manages the PKI system
• D. A security protocol

Answer: (B)

In PKI, a certificate binds a public key to an identity, and the subscriber is the entity whose identity is shown in the certificate and who owns the corresponding private key. The certificate’s subject field lists the subscriber’s name or identifier, making them the holder of the key pair used for signing or decrypting data. That’s why the subscriber is defined by whose name appears on the certificate—the certificate is issued to and represents that entity.

The other options don’t fit: a hardware device may store keys but isn’t the certificate’s owner; a PKI administrator is someone who manages the system, not the certificate’s holder; a security protocol is a method or rule set, not an entity.