(Unsure) Public key cryptography technology establishes the trust of users in each other through the public key infrastructure (PKI). PKI can transparently provide all network users on the basic platform with the key and certificate management necessary to use cryptography technologies such as encryption and digital signatures, and can provide confidentiality, authenticity, integrity, and non-repudiation for information transmission in the system. With four major technical supports, it has become an effective platform to ensure the security of online transactions and information transmission.