Multi-security-level cross-network electronic signature method and device based on one-way gatekeeper

The invention discloses a multi-security-level cross-network electronic signature method and device based on a one-way gatekeeper. The method comprises the steps that a low-security-level electronic signature system signs document data and affixes an electronic seal and an electronic signature, signature electronic seal data and signature data are generated, and the signature electronic seal data and the signature data are transmitted to a high-security-level electronic signature system through a one-way gatekeeper; the one-way gatekeeper judges whether the document data flows from the low-security-level electronic signature system to the high-security-level electronic signature system or not and whether the signature data is valid or not, and if not, transmission is terminated; if yes, sensitive data in the document data are recognized, data encryption is carried out to generate encrypted document data, and the encrypted document data, signature electronic seal data, a network user public key and a low-secre