What method uses encryption to ensure both integrity and authenticity of data?

A digital signature employs encryption techniques to provide both data integrity and authenticity. When a sender creates a digital signature, they generate a hash of the message and encrypt this hash with their private key. This process ensures that any alteration in the message would result in a different hash value, indicating that the data has been compromised. Moreover, the use of the sender's private key for encryption allows the recipient to verify the authenticity of the message by decrypting the hash with the sender's public key. If the decrypted hash matches the hash generated from the received message, it confirms that the message is not only intact (integrity) but also legitimately from the claimed sender (authenticity).

Other methods, such as checksums, primarily focus on integrity but do not provide authenticity. Firewalls serve as security barriers to control network traffic and protect systems, while redirection involves guiding users or data to different destinations, which does not inherently provide data integrity or authenticity.