Before the emergence of digital signature technology, there was a kind of "digital signature" technology, which was simply to sign on the handwriting board and then transmit the image to the electronic document. This kind of "digital signature" can be cut and pasted on any document, which is very easy to be copied illegally, so this kind of signature method is unsafe. Digital signature technology and digital signature technology are two completely different security technologies. Digital signature has nothing to do with user's name and handwritten signature form. It actually uses the sender's private key to convert the transmitted information. The digital signature of the sender is different for different document information. Without the private key, no one can complete illegal copying. In this sense, "digital signature" is an alphanumeric string obtained by processing the message to be transmitted through one-way function to identify the source of the message and verify whether the message has been changed.

In the concrete work of this technology, firstly, the sender performs mathematical transformation on the information, and the obtained information only corresponds to the original information; The original information is obtained by inverse transformation at the receiving end. As long as the mathematical transformation method is excellent, the transformed information has strong security in transmission and is difficult to decipher and tamper with. This process is called encryption, and the corresponding inverse transformation process is called decryption.

Digital signature can solve the problems of denial, forgery, tampering and counterfeiting. Specific requirements: the sender can't deny the message signature sent afterwards, the receiver can verify the message signature sent by the sender, the receiver can't forge the sender's message signature, the receiver can't partially tamper with the sender's message, and one user in the network can't impersonate another user as the sender or receiver. Digital signature is widely used, which is a breakthrough to ensure the security of electronic data exchange. Digital signature can be used in all occasions that need to identify users, such as encrypted letters, business letters, order purchasing systems, remote financial transactions, automatic mode processing, etc.