Method of using touch screen device for system encryption and protection

A method of using touch screen device for system encryption and protection, comprising: a system host transmits a packet in plaintext to a touch screen controller; and the touch screen controller receives and encrypts the packet in plaintext to generate ciphertext, and sends the ciphertext back to the host, thus realizing encryption inside the touch screen device (the plaintext and the ciphertext are exchanged through communication interfaces of the system host and the touch screen controller). The encrypting method enables important data (such as an account or a password) inputted by a user to be encrypted before being inputted into a system host, preventing important data from being stolen by malicious software when the data is being transmitted traditionally in the form of a packet in plaintext to an external encrypting device (such as a "dongle"), thus enhancing security of the touch screen device. In addition, the present invention facilitates system encryption of most handheld devices and mobile devices.