What is the role of a digital signature in secure communications?

• A. To compress data
• B. To encrypt messages
• C. To verify authenticity
• D. To share keys

Answer: (C)

A digital signature plays a crucial role in secure communications primarily by verifying the authenticity of a message or document. When a sender creates a digital signature, they use their private key to generate a unique code that corresponds to the data being transmitted. This signature functions as a tamper-evident seal; any changes to the message would invalidate the signature, alerting the recipient that the data has been altered or is not from the expected source.

The verification process involves the recipient using the sender's public key to validate the digital signature. If the signature matches, it confirms that the sender is indeed who they claim to be and that the message has not been tampered with during transmission. This ensures both integrity and authenticity in digital communications.

While other options, such as data compression, message encryption, and key sharing, are important aspects of information security, they do not specifically address the purpose of verifying a sender's identity and the integrity of the message in the way that a digital signature does.