With the development of medical technology and information technology, the “Personal Health Records (PHR)” is gradually developed as a up-to-date medical information exchange system. A proper patient-centered PHR system is able to offer correct and complete personal health and medical summary through the Internet under the demands of privacy and security, and integrate personal medical information from different sources. With the appearance of Cloud computing, a secure protection scheme is required to encrypt the medical records of each patient for storing personal health records into Cloud server.