Which method supports sender authentication and message integrity using a hash function?

A digital signature is a method that utilizes a hash function to ensure both sender authentication and message integrity. When a sender creates a digital signature, they first generate a hash of the message content. This hash is then encrypted with the sender's private key to create the digital signature.

Upon receiving the message, the recipient can decrypt the digital signature using the sender's public key, which reveals the hashed message. The recipient also generates their own hash of the received message. If the two hashes match, it confirms that the message has not been altered during transmission (message integrity) and verifies the sender's identity, since the signature could only have been generated with the sender’s private key (sender authentication).

This process is crucial in digital communications, as it helps establish trust and ensures that messages are secure from tampering and impersonation.