Identification and authentication information presented in the X.509 format and issued by a certificate authority as evidence that a key pair belongs to a particular subject is a

Identification and authentication information presented in the X.509 format and issued by a certificate authority as evidence that a key pair belongs to a particular subject is a

• A. X.509 format
• B. Digital certificate
• C. Certificate authority
• D. Public key

Answer: (B)

Binding a public key to an identity with a trusted issuer is what a digital certificate does. In X.509, a digital certificate is issued by a certificate authority and contains the subject’s identity, the public key, the issuer, a validity period, and a digital signature from the CA over the certificate data. When someone presents this certificate, others can verify the CA’s signature with the CA’s trusted public key, confirming that the public key really belongs to that subject and that the certificate is still valid. The X.509 format is just the encoding of this certificate, not the artifact itself; the certificate authority is the trusted issuer, not the evidence, and the public key is the cryptographic material, not the binding proof.

Binding a public key to an identity with a trusted issuer is what a digital certificate does. In X.509, a digital certificate is issued by a certificate authority and contains the subject’s identity, the public key, the issuer, a validity period, and a digital signature from the CA over the certificate data. When someone presents this certificate, others can verify the CA’s signature with the CA’s trusted public key, confirming that the public key really belongs to that subject and that the certificate is still valid. The X.509 format is just the encoding of this certificate, not the artifact itself; the certificate authority is the trusted issuer, not the evidence, and the public key is the cryptographic material, not the binding proof.