Certificates are documents that gather certain data from your titularasi as your public key and are signed electronically by Autoridadde certification using your private key. Autoridadde certification is a particular type of service provider Decertificacion that legitimizes, before third parties who rely on suscertificados, the relationship between the identity of a user and their clavepublica. Users confidence in the important certification authority for the operation of the service and justified their employment lafilosofia but there is a standardised procedure parademostrar that, a certification authority, deserve such trust. The public key and private key asymmetric cryptography is the metodocriptografico which uses a pair of keys for sending messages. Key both belong to the same person that message has been sent. A key is public, person unable to deliver any, the other key is a private and elpropietario must save it so that nobody has access to it.

In addition, cryptographic methods guarantee that this pair of clavessolo can be generated once, so that it can assume that not posible that two people have obtained coincidentally the same couple declaves. If the sender uses the recipient’s public key to encrypt message, once encrypted, only the private key of the recipient podradescifrar this message, because that is the only one who knows it. Therefore selogra the confidentiality of sending the message, nobody except the recipient can decrypt it. If the owner of the key pair uses its private key to encrypt message, anyone can decrypt it using your public key. Eneste case is achieved by identifying and autenticaciondel sender, since it is known that only could have been him who utilizosu private key (unless someone would have been able to steal it). This idea is the basis of the electronic signature.

It is certified electronic lafirma which gives it to document its value legalcomo e.g. an invoice electronically signed. The Ley59/2003 of the electronic signature equates, legally, lafirma electronic signature in paper, giving it of full validezlegal for public and private electronic transactions; and in elReal Decree 1496 / 2003 of 28 November, is determined the opportunities send invoices by electronic means.