In public key encryption for authentication, the receiver decrypts with the sender's public key.

• A. True
• B. False
• C. Not enough information
• D. Both

Answer: (B)

In authentication with public-key cryptography, the sender creates a signature on a message using their private key, and the receiver uses the sender’s public key to verify that signature. The public key is used to confirm that the signature was created with the corresponding private key, proving the sender’s identity and the message’s integrity.

Decrypting with the sender’s public key would imply recovering the original plaintext data, which is not how authentication works. Verifying a signature (not decrypting) is the correct step. For confidentiality, encryption would use the recipient’s public key so only the recipient can decrypt with their private key.