What is the purpose of a digital certificate in public key cryptography?

• A. To bind a public key to an entity's identity and verify trust via a trusted authority.
• B. To store private keys securely.
• C. To encrypt data in transit exclusively.
• D. To verify the recipient of encrypted data.

Answer: (A)

Digital certificates are about establishing trust by binding a public key to an entity’s identity through a trusted authority. A certificate holds the entity’s identity information, their public key, and the certificate authority’s digital signature. Anyone who trusts that CA can verify that the public key really belongs to that entity by checking the CA’s signature and the certificate’s validity period. This enables secure communications because other parties can confidently use the public key to encrypt data or verify signatures, knowing it’s associated with the claimed identity. A certificate does not store private keys, and it does not itself perform encryption; it provides the trust foundation that the key belongs to the stated entity. Revocation and the ability to trace the certificate back to a trusted CA further support ongoing trust in the system.