The widespread and fast-developing information technologies, especially wireless communications and the Internet, have allowed for the realization of greater automation systems than ever in health-care industries: E-health has become an apparent trend, and having a clinic at home or even anywhere at anytime is no longer a dream. E-health, including telemedicine featured by conducting health-care transactions over the Internet, has been revolutionizing the well-being of human society. Traditionally, common practices in the health-care industry place tremendous burdens on both patients and health-care providers, with heavy loads of paper-based documents and inefficient communications through mail or phone calls. The transmission of medical data is even messy for cases in which patients have to transfer between different health providers. In addition, the medical documents prepared manually are prone to errors and delays, which may lead to serious consequences. The time, energy, and resources wasted in such processes are intolerable and unimaginable in any fast-paced society. For these problems, e-health provides powerful solutions to share and exchange information over the Internet in a timely, easy, and safe manner (Balas et al., 1997). Incorporating fast and cost-efficient Internet and wireless communication techniques has enabled the substantial development of e-health. The use of the Internet to transmit sensitive medical data, however, leaves the door open to the threats of information misuse either accidentally or maliciously. Health-care industries need be extremely cautious in handling and delivering electronic patient records using computer networks due to the high vulnerabilities of such information. To this extent, security and privacy issues become two of the biggest concerns in developing e-health infrastructures.