In TLS, which function is primarily performed by the private key?

In TLS, which function is primarily performed by the private key?

• A. To encrypt data sent to clients
• B. To manage session keys
• C. To decrypt data encrypted with the public key and sign data
• D. To verify certificate authority

Answer: (D)

The private key in TLS is used for asymmetric operations that establish identity and trust during the handshake. Specifically, it is used to decrypt data that was encrypted with the corresponding public key (such as the premaster secret in RSA key exchange) and to sign handshake messages to prove possession of the private key. After the handshake, the session is protected with symmetric keys, so the private key isn’t used for bulk encryption of data. Verifying the certificate authority relies on the CA’s public key (found in trusted roots), not the private key. So the description that the private key decrypts data encrypted with the public key and signs data best captures its role in TLS.

The private key in TLS is used for asymmetric operations that establish identity and trust during the handshake. Specifically, it is used to decrypt data that was encrypted with the corresponding public key (such as the premaster secret in RSA key exchange) and to sign handshake messages to prove possession of the private key. After the handshake, the session is protected with symmetric keys, so the private key isn’t used for bulk encryption of data. Verifying the certificate authority relies on the CA’s public key (found in trusted roots), not the private key. So the description that the private key decrypts data encrypted with the public key and signs data best captures its role in TLS.