What is the purpose of a digital signature?

A digital signature serves the specific purpose of verifying the authenticity and integrity of a message. When a sender applies a digital signature to a message, they use their private key to create a unique code that corresponds to both the message content and the sender's identity. This ensures that the recipient can confirm that the message was indeed sent by the claimed sender (authenticity) and that the message has not been altered in any way during transmission (integrity).

Digital signatures utilize cryptographic techniques to provide a level of assurance that can be relied upon in digital communications. When the recipient receives the signed message, they can use the sender's public key to validate the signature. If it verifies correctly, they can trust that the message was not tampered with and is indeed from the stated sender.

The other choices, while related to data protection and management, do not align with the fundamental function of a digital signature. Encrypting data is primarily focused on securing information from unauthorized access, compressing files is about reducing file size for efficient transmission, and backing up information is related to data preservation rather than authenticating a sender or ensuring message integrity.