Digital certificate (also known as digital identification) refers to the electronic document issued by CA organization, which is a series of numbers that can display the identity information of network users, and provides a way to verify the identity of network users on the computer network.

The function of digital certificate is to ensure the confidentiality of information transmission, the integrity of data exchange, the non-repudiation of sent information and the certainty of trader's identity.

Digital certificate holders have a pair of public keys and private keys, which can encrypt and decrypt each other. The public key is public and does not need to be kept secret. The receiver of an electronic contract can check the identity of the signer through public key decryption, which is used to verify whether the electronic contract is signed by the signer. The private key is held by the certificate holder and used for electronic signature encryption. The electronic contract platform issues digital certificates to users through CA certification bodies, and realizes electronic signature based on the digital certificates.