How does SSL secure data transmission?

How does SSL secure data transmission?

• A. By using a shared secret to encrypt data
• B. By using a private key to sign messages
• C. By using a public key to encrypt data
• D. By rotating keys every hour

Answer: (C)

SSL secures data by establishing a session key securely and then using that key to encrypt the actual data with a fast symmetric cipher. In the handshake, the server’s certificate provides a public key. The client uses that public key to send something that only the server can decipher with its private key (the secret used to derive the session key). Once both sides derive the same session key, all subsequent communication is encrypted with symmetric encryption, which is efficient for large data transfers. The idea is that public-key cryptography protects the key exchange, while symmetric encryption protects the data itself. Rotating keys every hour isn’t a required part of SSL’s standard operation.

SSL secures data by establishing a session key securely and then using that key to encrypt the actual data with a fast symmetric cipher. In the handshake, the server’s certificate provides a public key. The client uses that public key to send something that only the server can decipher with its private key (the secret used to derive the session key). Once both sides derive the same session key, all subsequent communication is encrypted with symmetric encryption, which is efficient for large data transfers. The idea is that public-key cryptography protects the key exchange, while symmetric encryption protects the data itself. Rotating keys every hour isn’t a required part of SSL’s standard operation.