Which item is issued by a certificate authority to guarantee that a key pair is valid for a particular subject?

Which item is issued by a certificate authority to guarantee that a key pair is valid for a particular subject?

• A. Root certificate
• B. Public key
• C. Digital certificate
• D. Certificate signing request

Answer: (C)

A digital certificate is the binding of a public key to a subject’s identity, issued by a trusted certificate authority. It includes the subject’s name, the public key, the issuer’s identity, a validity period, and a digital signature from the CA over those fields. This signature, verifiable with the CA’s own public key, provides proof that the key pair belongs to that particular subject, assuming you trust the CA. The certificate may also include revocation information to address compromised keys. Why this fits best: the certificate is specifically designed to prove that a given public key actually belongs to the stated subject, as vouched for by a trusted authority. A root certificate is the trust anchor used to sign other certificates, not the binding for a particular subject. A public key by itself carries no identity. A certificate signing request is just a request to issue a certificate, not a binding that has been issued.

A digital certificate is the binding of a public key to a subject’s identity, issued by a trusted certificate authority. It includes the subject’s name, the public key, the issuer’s identity, a validity period, and a digital signature from the CA over those fields. This signature, verifiable with the CA’s own public key, provides proof that the key pair belongs to that particular subject, assuming you trust the CA. The certificate may also include revocation information to address compromised keys.

Why this fits best: the certificate is specifically designed to prove that a given public key actually belongs to the stated subject, as vouched for by a trusted authority. A root certificate is the trust anchor used to sign other certificates, not the binding for a particular subject. A public key by itself carries no identity. A certificate signing request is just a request to issue a certificate, not a binding that has been issued.