CAs distribute public keys ________.

• A. Only encrypted transfers
• B. Both A and B
• C. Neither A nor B
• D. In digital certificates

Answer: (D)

Public keys are shared through digital certificates issued by a Certificate Authority. A CA verifies an entity’s identity, creates a certificate that binds the entity’s public key to that identity, and signs the certificate with the CA’s private key. This signed certificate can then be distributed and used by others to verify that the public key really belongs to the claimed entity, as trusted by the CA’s root or intermediate certificates.

That’s why the correct choice is that public keys are distributed in digital certificates. Distributing keys only via encrypted transfers isn’t the mechanism that provides identity binding and verifiable trust, and there isn’t a need to rely on some other method for key distribution when digital certificates already serve this purpose.