Digital Signature

Digital Signature

Que son Firmas Digitales ?
Una firma digital es el equivalente electronico a la firma de una persona. Es utilizado entre otras cosas para validar la autenticidad de quien envia un mensaje. Provee informacion sobre el contenido del mensaje adjunto que no puede ser interceptada ni manipulada entre el que envia y recibe los datos.

Por ejemplo un email firmado con una firma electronica no puede ser repudiado, es decir el que lo envia no puede negar que lo envio, ademas se asegura que el contenido del mensaje no fue cambiado y provee un sello electronico que confirma la fecha y hora de transmision.

Para que una firma digital sea reconocida debe berificarse la integridad del que envia y recibe. Por esa razon existe una autoridad certificadora (CA) que provee una firma digital a personas que permite identificar y verificarlos, tal y como el sello de un abogado en un documento valida el nombre y firma de una persona.

Para proveer mayor confianza la firma digital es acompañado siempre con el certificado de la autoridad certificadora Certification Authority, and this too may be inspected for validity and expiration. Most people expect digital signatures to totally replace the use of the ('old fashioned') pen and ink signature with orders and authorities being accepted via digitally signed e-mails, the contents of which may, or may not, be encrypted for additional security. N.B. In July 2000, Digital Signatures became legally accepted in the United Kingdom under Section 7 of the Electronic Communications Act. In the USA also, Congress approved the use of Digital Signatures for certain types of e-Business around the same time under the E-Sign Act. Because both Acts are extremely new, it is strongly recommended that legal advice be sought before reliance is placed upon this new legislation.

digital signature
A digital signature uses encryption technology to do two things. It proves that the message hasn’t been changed in transit, called message integrity, and it also links ownership to the information, called non-repudiation.

In order to prove that the message wasn’t changed the message is cryptographically transformed to a set of values, called a hash or a digest. The hash or digest is also sometimes referred to as a fingerprint because statistically, the chance of this hash or digest being the same value for any other message is almost impossible. The hash or digest is sent along with the message and the same transformation is run at the other end. Any attempts to alter the information in transit will result in a message that no longer matches its digital signature.

In order to link ownership, before the message is sent, a second operation is performed. The private key of the sender is used to encrypt the hash or digest. The receiver uses the sender’s public key to decrypt the digest. This proves that the message could only come from the person who holds the private key.

digital signature Certificado 2018