In the cross-border electronic commerce Transaction Contract, the legal definition of electronic signature is: "Electronic signature refers to the data contained in the data message in electronic form, attached to the data message or logically related to the data message, which can be used to identify the signer related to the data message and show that this person recognizes the information contained in the data message." Later, it is proposed that the participants in electronic signature activities mainly include signers, certification service providers and relying parties. Signatory means a person who holds electronically generated data and acts in his own capacity or in the name of the person he represents; A certification service provider refers to a person who issues certificates or can provide other services related to electronic signatures; Relying party refers to a person who can act according to a certificate or an electronic signature.

Generally speaking, it actually refers to the existence in electronic form, attached to the electronic document and logically associated with it, which can be used to identify the identity of the signer of the electronic document, ensure the integrity of the document, and show that the signer agrees with the factual content stated in the electronic document. Electronic signature is not a digital image of handwritten signature and seal, it exists in the form of electronic code and must be bound with digital certificate.

From this definition, we can see that electronic signature is essentially a kind of data and an electronic form attached to data telecommunications, which must meet three conditions: first, the signer cannot deny the fact that he signed afterwards; Second, no futures person can forge this signature; Thirdly, if both parties dispute the authenticity of the signature, an impartial third party can arbitrate and verify the authenticity of the signature.