A digital signature is an electronic authentication mechanism that uses cryptographic keys to associate a document or message with the holder of a private key. The corresponding public key allows the recipient to check whether the signature is valid and whether the content has changed since signing. It can therefore provide evidence of the signer’s control of the relevant key and make subsequent denial more difficult, subject to the security of the key and the systems used to manage it. A digital signature is one form of electronic signature; electronic signatures do not necessarily rely on cryptography.
Source: European Central Bank (ECB) (source). This glossary entry is an independently worded adaptation of the cited information.