While the timestamp proves a document’s existence in time, an electronic signature with a qualified certificate confirms who the author of a particular electronic document is. The qualified certificate is issued exclusively by an accredited certification authority upon verification of the identity of the applicant to whom such certificate should be issued.
Like a timestamp, an electronic signature ensures the integrity of a signed document – any modification to a previously signed document would render the signature invalid.
Whenever it is necessary to confirm the existence of a signed document in time, it is necessary to combine the signature with a timestamp - either directly as a part of the document or as a separate file related to the document.
The qualified certificate must be used in communications with state authorities.
The qualified certificate can be also issued for technological equipment providing electronic documents with signatures automatically. In this case, a qualified system certificate of technological component is used. The signatures issued by this certificate are called "electronic tags".