Which technology is used to issue certificates and bind public keys to user identities?

• A. Public Key Infrastructure
• B. Virtual Private Network
• C. Domain Name System Security Extensions
• D. Transport Layer Security

Answer: (A)

Public Key Infrastructure (PKI) is the framework that issues digital certificates and binds public keys to real identities. It includes entities like Certificate Authorities that issue certificates after verifying identities, and mechanisms to publish, validate, and revoke those certificates. A certificate ties a public key to a specific subject, and the CA’s digital signature on that certificate provides the trust that the key really belongs to that user or system. This binding is what enables others to trust communications and verify identities in secure protocols, such as TLS, which relies on certificates issued by PKI to establish encrypted connections.

VPN is about creating secure tunnels, not issuing certificates. DNSSEC is about securing DNS data integrity, not linking public keys to user identities. TLS uses certificates issued by PKI, but does not perform the issuance itself.