What is a common use of a digital signature?

A digital signature is primarily used to verify the sender's identity and to ensure the integrity of a message or document. When a digital signature is applied to a message, it generates a unique hash of the content that is encrypted with the sender's private key. This allows the recipient to decrypt the signature using the sender's public key, confirming that the message was indeed sent by the purported sender and has not been altered during transmission.

Moreover, the application of digital signatures is fundamental in various secure communication protocols, such as SSL/TLS, and in software distribution to ensure that the software comes from a trusted source and hasn’t been tampered with.

The other options relate to processes that do not involve the authentication aspect provided by digital signatures. For example, data compression is about reducing the size of data for storage or transmission without regard for its authenticity. Allocating IP addresses pertains to network management rather than verifying identities. Preventing bandwidth throttling is related to maintaining consistent network speeds and performance, which does not involve authenticity or integrity verification of data. Thus, the role of digital signatures is specifically linked to identity verification and message integrity, making it a crucial element in secure communications.