How does a digital signature function?

A digital signature functions primarily by verifying the authenticity of a message. It provides a way for the sender of a message or document to ensure that it has not been altered and that the identity of the sender is legitimate. This is accomplished through the use of cryptographic techniques. When a sender applies a digital signature to a document, they create a unique hash of that document, which is then encrypted with their private key. The resulting digital signature is appended to the document.

When the recipient receives the document, they can use the sender's public key to decrypt the signature and retrieve the original hash. By comparing this hash to the hash they generate from the received document, they can confirm that the document has not been modified since it was signed and also verify that it truly comes from the claimed sender. This process significantly enhances the security of electronic communications and transactions by ensuring integrity and authenticity.

Other options discuss unrelated aspects of document handling. For instance, indicating the date and time of creation is not the function of a digital signature; rather, it might be a feature of the file system. Compressing the document size is also unrelated, as digital signatures do not alter the size of a file. Facilitating easier sharing of documents, while a benefit of digital signatures in