A digital signature is a cryptographic method for verifying the identity of an individual, a process, computer system, or any other entity, in much the same way as a handwritten signature verifies the identity of a person. Digital signatures use the properties of public-key cryptography to produce pieces of information that verify the origin of data.

Cryptography is the science of using mathematics to keep information from people who should not be able to see it. Secret-key (or private-key) cryptography uses a single key for both hiding (encrypting) and revealing (decrypting) data. Public-key cryptography, in contrast, uses two keys that are related by a mathematical function.

The two keys are called the "public key" and the "private key" and the relationship between them is such that knowledge of the public key does not give sufficient information about the private key for someone to work out what...