"Digital signature" refers to data that exists in electronic form in data information, or data that is attached to or logically related to data information. It can be used to identify the identity of the data signer and show the signer's approval of the information contained in the data information. A set of digital signatures usually defines two complementary operations, one for signing and the other for verification.

Digital digest is to change a message of arbitrary length into a short message of fixed length, which is similar to a function that takes the message as an independent variable, that is, a hash function.