A digital signature is a mathematical technique that is used to validate the authenticity of a message, webpage, or other document. Digital signatures can be used to give the reader reason to believe that the message or document was sent from the party the file claims it was sent from and that the document was not altered or intercepted during transit. Digital signatures range in structure and use and may be held to varying legal responsibilities, depending on the country in which it was signed and received.

 

How Digital Signatures Work

A digital signature consists of three algorithms: one for key generation, one for signing, and one for signature verification. The key generation algorithm must select a private key from a list of possible private keys and generate a corresponding public key. The signing algorithm uses a message and a private key to generate a signature. The signature verification algorithm then uses the message, private key, and public key to either accept or reject the authenticity of the digital signature. The idea is that a digital signature cannot be faked unless the forger knows the private key, which is randomly selected.

 

Applications

Digital signatures are used for a wide variety of applications. For example, digital signatures can be used in conjunction with digital certificates to verify that a web store or other online institution has the appropriate credentials to keep a user’s information secure. Digital signatures can also be used for signing legal documents online and are usually considered real signatures in the United States.