"An electronic signature is a series of digital codes attached to the document, which means that an electronic signature is not visible on a digital document, therefore a document can have an invisible electronic signature.
Visual aspects such as names, surnames, stamps or QR codes do not imply or validate that a document is electronically signed. The only reliable way to validate that a document has an electronic signature is to do so using validation software such as Adobe (provided it has the certification chain of the provider), FirmaEC, or quickly and easily through the online electronic signature validator [https://www.verificafirma.it/]."