Method, terminal device, and network device for improving information security

A method, a terminal device, and a network device are provided. The method of the present invention includes acquiring, by a terminal device, a key, an identity of the terminal device, and identification information of one or more applications on the terminal device, where identification information of different applications on the terminal device is different from each other, and the identity of the terminal device includes International Mobile Equipment Identity (IMEI) and/or International Mobile Subscriber Identity (IMSI); generating, for identification information of one application by using a preset encryption algorithm according to the identity of the terminal device and the key, an encryption result corresponding to the application; and when the application runs on the terminal device, accessing a network by using the encryption result corresponding to the application. The present invention is applicable to protecting information security of a terminal device accessing a network.