What does a digital signature ensure regarding a document?

A digital signature serves a critical role in ensuring the integrity and authenticity of a document. By creating a unique digital fingerprint of the document using cryptographic techniques, a digital signature guarantees that any alterations made to the document after it has been signed can be detected. This means that if someone attempts to change the content of a digitally signed document, the signature will no longer be valid, alerting the recipient to potential tampering.

The main purpose of a digital signature is to provide assurance that the document has not been altered since it was signed, thereby preventing unauthorized modifications. This is particularly important in legal, financial, and other sensitive communications where the accuracy and authenticity of information are paramount.