A few concepts need to be extended here:

1. The public key can be obtained and used by everyone, while the private key is private and only you know it but not others. Get.

2. Symmetric encryption: Encryption using a single-key cryptosystem, that is, only the same password can be used for information encryption or decryption.

3. Asymmetric algorithm: It has two unique keys, one public key and one private key. It has the following properties: files encrypted with the public key can only be decrypted with the private key, and the private key Files encrypted with a public key can only be decrypted with the public key.

In order to illustrate the role of digital signature technology in the electronic signature process, we illustrate through an electronic signature scenario: Suppose company A sends a confidential document to company B, which requires company B to sign online using an electronic signature. , then the steps are:

(1) Company A sends the file to Company B

In order to ensure that the file content is not leaked during the transmission process, Company A uses symmetric encryption to encrypt the file and sent to Company B.

In order to ensure that only Company B receives the secret key encrypted in the above steps, Company A encrypts the secret key with Company B's public key (then only Company B can open it using the private key).

(2) Company B receives and signs the document

After Company B receives the file, it uses its own private key to decrypt the file to obtain the file content;

Company B Add a signature appearance to the file to form a new file with the seal appearance + file content;

Convert the new file into a piece of code (the technology is a hash operation, and the code is a hash value);

Use Company B’s private key to encrypt the hash value, forming Company B’s digital signature.

From the above process, it can be seen that the digital signature is the hash value of the source file extracted using a hash algorithm and encrypted with the sender's private key. Since the source file summary content is unique , so the digital signature is also unique. The process of forming a digital signature and adding it to the source document and sending it to the signer is the process of electronic signature.