What is digital signatures?
A digital signature is a mathematical technique used to validate the authenticity and integrity of a message, software, or digital document.
The digital equivalent of a handwritten signature or stamped seal, but offering far more inherent security, a digital signature is intended to solve the problem of tampering and impersonation in digital communications. Digital signatures can provide the added assurances of evidence to origin, identity and status of an electronic document, transaction or message, as well as acknowledging informed consent by the signer.
How digital signatures work
How to I use digital signature with USB token on web?