Electronic signatures usually provide

• A. Message-by-Message Authentication
• B. Message Integrity
• C. Both A and B
• D. Neither A nor B

Answer: (C)

Electronic signatures bind the signer’s identity to the exact content and ensure the content hasn’t been altered since signing. By signing the message with the signer’s private key and allowing verification with the public key, you get two things for each signed item: authentication of who signed it and integrity of the message. Because this happens for each individual message, you have per-message authentication and per-message integrity. Remember, signatures don’t hide the content; confidentiality would require encryption.