Secure communication between lightweight computing devices over the internet

The advent of light, low-power handheld compute devices such as Windows CE, PalmTM and Handspring, is changing the way in which mobile users interact with their home o ce. These devices can be connected to the Internet through both physical and wireless connections, and sensitive data transferred to and from these devices are subject to interception by a third party. Real-time encryption/decryption of data in handheld computers is complicated by the limited computing power available in these devices. In this paper we describe a method for secure transmission of data between remote handheld devices and other users (including other handheld devices) on the Internet. The system relies on one-time-pad technology which is ideally suited for handheld computing. The process of encrypting/decrypting data requires very little computation, and the generation of the random pads can be accomplished outside of the handheld devices. A prototype system is described which permits secure transmission of data through IR, radio Ethernet, or physical connection.