At present, all kinds of PDF/OFD documents have no digital signatures, and some of them may have electronic seals. These documents without digital signature are not credible, because anyone can easily impersonate a company to publish such documents, or even impersonate and tamper with official documents issued by the government. How to ensure the credibility of publishers of various electronic documents/official documents is not only a compliance issue, but also a huge security risk, which can easily lead to people being cheated, losing money and even hurting their lives. This is a problem that must be solved in the paperless transformation of enterprise management.

At present, the only feasible solution is to use digital signature on electronic documents to ensure the credibility of the identity of the document publisher and ensure that the document will not be illegally tampered with or forged. China's "Electronic Signature Law" has made it clear that a reliable electronic signature has the same legal effect as a handwritten signature and a company seal, and this reliable electronic signature refers to a digital signature. Digital signature is an undeniable signature behavior that uses digital certificate to verify the identity of the signer, and binds the signer's identity to the document through cryptographic algorithm. The signed document does not need to contain the audit report of the signing process, and the identity verification of the signer is completed by a certification authority (CA) or a trusted service provider (TSP).

Document signature only solves the problem that the identity of the document publisher can be trusted and prevented from being illegally tampered with. Confidential documents need to be encrypted with certificates to ensure that even if electronic documents are leaked, they cannot be decrypted because they cannot obtain encryption certificates, thus ensuring the security of the documents. This is why Article 34 of GDPR says that as long as they are encrypted, once data is leaked, the responsibility can be reduced.

A supporting service of document signature is timestamp signature, because the default time in electronic documents is the user's computer time, which is not credible and can be modified at will. Therefore, the release time of various important documents, including the signing time of electronic contract documents, needs an authoritative and tamper-proof time to prove the signing time of documents. The document digital signature service provided by Mi Xin APP is free of charge. With the authoritative timestamp service trusted by Adobe worldwide, the signature time of each signed document is ensured to be credible, tamper-proof, forgery-proof and undeniable.