Abstract: A method of using touch screen device for system encryption and protection includes sending plaintext to a touch screen controller by a host; and receiving and encrypting the plaintext to generate ciphertext by the touch screen controller, and returning the ciphertext to the host, thus realizing encryption inside the touch screen device (the plaintext and the ciphertext are exchanged through communication interfaces of the host and the touch screen controller). The encrypting method enables important data (such as accounts or passwords) inputted by a user to be encrypted before being inputted into a system host, thereby preventing the important data from being stolen by malicious software when the data is being transmitted in the form of plaintext to an external encrypting device (such as a “dongle”), thus enhancing security of the touch screen device. Further the method facilitates system encryption of most handy devices and mobile devices.