An electronic signature that you can use to sign a document being transmitted by electronic means such as e-mail. Digital signatures validate the identity of the sender and ensure that the document they are attached to has not been altered by unauthorized parties during the transmission.
Digital signatures are based on public key cryptography systems. In order for digital signatures to work, the sender must have both a digital certificate and a key pair issued by a certificate authority (CA) such as VeriSign, Inc.A digital signature for a particular document is created using a mathematical hash of the document, which is then encrypted using the sender’s private key. The resulting signature is attached to the document and transmitted. The receiver performs the same hash on the received document using the sender’s public key. If the two hashes match, it means that the message has been transmitted without corruption by the identified sender. Note that the particular content of a digital signature depends on the document being transmitted; it is different for each document sent.