Key and certificate management required by encryption technology such as encryption and digital signature. Public key encryption technology establishes trust between users through public key infrastructure (PKI). The function of digital signature is to manage the keys and certificates necessary for cryptography technologies such as encryption and digital signature, which can provide four technical supports for information transmission in the system, namely confidentiality, authenticity, integrity and non-repudiation, and become an effective platform to ensure the security of online transactions and information transmission.