What is it?
It is a mechanism that preserves the integrity of an electronic document through content encryption and the use of a digital certificate.
When a document is signed, all content is encrypted using a hash function and the private key of a digital certificate, so the full content is represented by a unique hash code.
As a result, if the document content changes after signing, the generated hash will no longer match the new content and the system will report that the document has been modified.