What is a primary use of a digital signature in data security?

A primary use of a digital signature in data security is ensuring data authenticity and integrity. Digital signatures provide a means to verify that a message or document has not been altered in transit and confirm the identity of the sender. When a sender digitally signs a document using their private key, a unique hash of the document is generated and encrypted with that key. The recipient can then decrypt the signature using the sender's public key, which allows them to confirm the signature's validity and ensure that the content has not been tampered with.

This process plays a crucial role in maintaining trust in digital communications and transactions, especially in environments where data integrity and authenticity are critical, such as financial services and electronic contract signing. Other options, such as enhancing file size or speeding up downloads, do not relate to the foundational purpose of a digital signature. While facilitating software updates may involve the use of digital signatures to verify the integrity of software, this is more a secondary application rather than the primary role of digital signatures overall.