A digital signature or digital signature scheme is a type of
asymmetric cryptography used to simulate the security properties
of a handwritten signature on paper. Digital signature schemes
consist of at least three algorithms: a key generation
algorithm, a signature algorithm, and a verification algorithm.
A digital signature mainly provides authentication of a
"message". In theory it can also provide non-repudiation ,
meaning that the authenticity of signed messages can be publicly
verified, not only by the intended recipient. Messages may be
anything, from electronic mail to a contract , or even a message
sent in a more complicated cryptographic protocol Digital
signatures are often used to implement electronic signatures, a
broader term that refers to any electronic data that carries the
intent of a signature, but not all electronic signatures use
digital signatures. In some countries, including the United
States, and in the European Union, electronic signatures have
legal significance. However, laws conce