The emergence of digital certificates is to solve the problem of forging public keys. Digital certificates are issued by the authority CA, also known as the certificate authority center, which can be used to identify the identity of the other party on the Internet. They are a series of numbers that identify the identity information of all communication parties in Internet communication, and provide a way to verify the identity of communication entities on the Internet. A digital certificate is not a digital ID card, but a seal or stamp stamped by an identity authentication institution (or a signature added to a digital ID card).