The emergence of the so-called electronic signatures has been without doubt one of the main developments in the problem of non-face authentication, allowing us to validate the true identity of users, and integrity of the message that we have transferred electronically. Among its many benefits, allows anyone to perform remote operations in an environment of security from the government or to the banks, shares its particular features not feasible with a simple e-mail or by unauthenticated access our web browser, since they require a comprehensive warranty as to the question of the identity of the different participants. In technical terms, is a cryptographic method that relates the identity of a person or a computer system with a message or document. Depending on the type of signature, would allow further authenticate the perfect integrity of the document. For Spain, the legal rules set up three types of signatures: the "simple", which allows identifying the signatory; "advanced", which also ensures the integrity of the message, and the company "recognized", also known as "qualified", consisting of an advanced signature complemented with a qualified certificate. In order to enjoy the many possibilities associated with electronic signatures (also called digital signatures) will need a digital certificate.
The certificates used are those issued by that is, the Fabrica Nacional de Moneda y Timbre, along with the so-called electronic ID document that contains a digital certificate and is a suitable tool to be used to electronically sign any document, and also to validate the identity of the signer. If we opted for the use of electronic ID, we need a "device" known as "electronic card reader." Thanks to our ID card and a card reader, and knowing the corresponding key, we are enabled to validate them safely, and access to different tasks in the network. One is the generation of invoices in electronic format. These bills to be signed electronically in a secure, do not need the typical support role and subsequent transmission by post. The electronic file is therefore, in addition to insurance, fully legal. Although Spain already has the technical and regulatory structure for the progressive development of electronic signatures, there is still enough to spread its use, so that citizens and organizations aware of and fully utilize their applications.