The present invention discloses a method, a system and a computer-readable medium so that a user, by using a mobile device containing an interface, can perform the signature of documents by a digital handwritten signature, this signature states that full legal value and documentation can be signed from Fin Tech companies, banks, insurers, customs and foreign trade agencies, marketers, lessors, and companies with legal certainty needs in mobile and virtual environments, where the mobile device through the interface notifies at least one user that they have a document to sign, document signature processing is performed by verifying the identity of the user by an identification document, and finally processes the signature and verifies the user's identity to the check, by facial biometry, a photo obtained by the mobile device with the photograph of the user identification document.