Encryption is done at A and decryption is done at B. A adds a digital signature s to message S using public key cryptography, encrypts. (Networking)

• A. Encryption: A’s private key followed by B’s public key; Decryption: B’s private key followed by A’s public key.
• B. Encryption: A’s public key followed by B’s private key; Decryption: B’s public key followed by A’s private key.
• C. Encryption: A’s private key followed by B’s private key; Decryption: A’s public key followed by B’s private key.
• D. Encryption: A’s private key followed by B’s private key; Decryption: A’s public key followed by B’s public key.