Digital signature

A digital signature is an object that can be used to authenticate the author of a document or message.

Digital signatures are usually based on public-key cryptography, in which a key is created as a pair of keys, with the property that, if some input is encrypted with one key, it can only be decrypted with the other key, and vice versa.

The creator of the key pair makes one of the keys public and keeps the other one private. To sign a document, the key pair’s owner creates a hash of the document and encrypts it with the private key.