What is the purpose of a digital signature?

• A. To encrypt the contents of a file
• B. To verify the authenticity and integrity of a message or document
• C. To enhance the visual appearance of digital documents
• D. To enable file sharing across platforms

Answer: (B)

A digital signature serves the important function of verifying the authenticity and integrity of a message or document. When a digital signature is applied to a file or message, it provides a means for the recipient to confirm that the message was indeed created and sent by the claimed sender. Additionally, it ensures that the contents of the message have not been altered during transmission.

This is achieved through cryptographic methods. When the sending party signs the document, a hash (a fixed-size string of characters) of the message is created and encrypted with the sender's private key, forming the digital signature. When the recipient receives the document, they can use the sender’s public key to decrypt the signature, verify the hash, and confirm that the document has not been tampered with since it was signed.

The other options highlight different aspects of technology. While encryption can be related to security in digital communications, its primary goal is to protect the confidentiality of the information rather than its integrity and authenticity. Enhancing the visual appearance of documents pertains more to formatting and design rather than security features. File sharing across platforms focuses on interoperability and accessibility, which are not directly connected to the function of a digital signature.