Answer: A

This question tests the basic knowledge of electronic signature technology.

Electronic signatures have legal effect. From a technical point of view, electronic signatures exist in electronic form, are attached to electronic documents and are logically associated with them. They can be used to identify the identity of the signer of the electronic document and ensure that the document is not damaged during transmission (that is, to ensure the integrity of the electronic document) , and indicates that the signer agrees to the contents of the electronic document. Confidentiality and integrity are not the same concept. Confidentiality requires that information will not be disclosed to unauthorized persons, while integrity requires that information will be destroyed for various reasons. The confidentiality of electronic documents often needs to be provided by encryption technology. Electronic signature technology and encryption technology are independent of each other, although the two are often used together.