Why can't the electronic seal of the third-party platform be tampered with? The specific method of electronic seal is to effectively bind the digital signature of electronic document content with the image of electronic seal through digital watermarking, encryption and other technologies (such as hiding data in the image of electronic seal by using hiding technology). Electronic seal is a kind of signature, and a reliable electronic seal should not be tampered with at will! Article 13 of the Electronic Signature Law stipulates that an electronic signature shall be regarded as reliable if it meets the following conditions at the same time: (1) If the electronic signature production data is used for electronic signature, it belongs to the electronic signatory; (2) When signing, the electronic signature production data is only controlled by the electronic signer; (3) Any changes to the electronic signature after signature can be found; (4) Any changes to the content and form of the data message after signature can be found. The parties can also choose to use electronic signatures that meet their agreed reliable conditions. Article 14 stipulates that a reliable electronic signature has the same legal effect as a handwritten signature or seal.