A digital certificate is issued by an authoritative institution - Certificate Authority (CA) center, which can provide an authoritative electronic document for identity authentication on the Internet. People can use it to prove their identity and identify the identity of the other party in Internet communication.

Working principle: There are many numbers and English in the digital certificate. When using the digital certificate for identity authentication, it will randomly generate a 128-bit identity code. Each digital certificate can generate a corresponding number that cannot be the same every time, thereby ensuring the confidentiality of data transmission, which is equivalent to generating a complex password.

The digital certificate binds the public key and the real identity of its holder. It is similar to the resident ID card in real life. The difference is that the digital certificate is no longer a paper certificate, but a piece of electronic data containing the identity information of the certificate holder and approved and issued by the certification center. It can be used more conveniently and flexibly in e-commerce and e-government.

Currently, the format of digital certificates generally adopts the international standard X.509V3, which includes the certificate serial number, the name of the certificate holder, the name of the certificate issuer, the certificate validity period, the public key, the digital signature of the certificate issuer, etc.

As of now (2009022), there are a total of 28 legal digital certificate certification agencies established in accordance with the law in China.