Who vouches for the identity of an individual or organization within a public key infrastructure?

• A. Digital Signature
• B. Hash
• C. Certificate Authority (CA)
• D. Time server

Answer: (C)

In a PKI, trust is established by a Certificate Authority. The CA is a trusted third party that verifies the identity of an individual, organization, or device before issuing a digital certificate that binds the subject’s public key to that identity. The certificate, containing the public key and identity details, is digitally signed by the CA, creating a chain of trust that others can rely on to confirm the key belongs to the stated entity. There can be a root CA and subordinate CAs forming a hierarchy to manage this trust.

Digital signatures prove data origin and integrity, but they don’t by themselves establish or vouch for the real-world identity of a person or organization within PKI. A hash is a fingerprint of data used for integrity checks, not identity verification. A time server provides timestamps and does not verify identity.