適用於電子醫療環境之安全驗證機制

Abstract

在醫療領域中，隨著情境、地區的不同會衍生出不同的醫療環境。除了一般看病的醫院與診所外，還有病人危急狀態時所需要的急診、高山，離島偏遠地方因資源限制而建置設備較不完善的衛生所、以及醫院內部擁有的病歷管理中心。這些環境當中，無論是系統間或使用者間，都可能因為病人就診、臨床研究或是醫生查閱而需傳送有關病人受保護之健康資料。因此，確保這些資料可在網路上安全無疑的傳輸並保證這些資訊的隱私性與完整性是重要的議題。 驗證機制將運用來確保這些隱私資訊不被非法人員欺騙而獲得。並且，基於通行碼基礎的驗證機制因為密碼的有效率性而成為最被廣泛使用的方法。在這種機制之中，每個使用者都可在不需任何額外輔助的設備下，選擇往後機制驗證流程中自己使用的密碼並且可以牢記在心。 然而，在眾多醫療環境中，隨著環境的不同會有著不同的需求，因此一般的通行碼驗證機制並無法適用於這些特殊的醫療環境上。故此，本論文提出了三個基於不同形式的驗證機制，意即，系統式，使用者式以及行動式的驗證機制來滿足各種環境的需求。 這些機制不僅能抵抗各種惡意的網路攻擊，諸如通行碼猜測攻擊、重送攻擊、竊取伺服器驗證值攻擊、伺服器偽裝攻擊、或是偽冒攻擊等，而且能提供完美的前向安全性。 此外，為了證明這些機制確實能適用於醫療環境上，本論文亦說明它們可以符合健康保險可攜性與責任法案的安全規範。其為美國聯邦政府在1996年所制定的法案，是目前美國最重要的針對醫療資訊的法案。它主要是用來規範醫療資訊應用及病患的隱私權。該法案最重要的部分在於它所訂立的隱私與安全規範。隱私規範記載著有關病人如何理解與控制對於使用他們所受保護之健康資料的權力。而安全規範則是依照怎樣做是安全的與如何實際實行之需求準則與特殊規範來定義。對於建構一個安全的醫療環境，滿足隱私與安全兩大規範裡的法則是重要的。

In medical domain, different medical environments would be generated with various contexts and regions, such as general hospitals and clinics, where people go for healthcare, emergency rooms, where patients in the crisis, deficient health centers in mountain, outlying islands, and remote areas, and the medical record management center in hospitals. In these environments, the protected medical information is likely to be transmitted among systems or users for patient treatments, clinical research, or doctor enquiry. The safe transmission on the network and the guarantee of the information privacy and integrity are the critical issue. An authorization mechanism would be used to ensure the private information is not obtained fraudulently by illegal persons. The password-based authentication scheme is the most widely employed method because of its efficiency. Under such mechanism, each user is allowed to select his password and keep in mind without any additional assistant device for the further authentication process. Nonetheless, different requirements are presented on various medical environments. General authentication schemes therefore cannot be applied to special medical environments. For this reason, this study proposes three authentication schemes, namely system-based, user-based, and mobility-based, for various environmental demands. Not only various malicious attacks such as replay attacks, password guessing attacks, stolen-verifier attacks, server spoofing attacks, impersonation attacks can be resisted but also the perfect forward secrecy is preserved in these schemes. In addition, this study further explains these schemes can conform to the security regulations of Health Insurance Portability and Accountability Act so that they are appropriate to be applied in medicine environments. Health Insurance Portability and Accountability Act, the law of United States Federal Government enacted in August 1996, is the most important Act for electronic medicine and is applied to standardize the medical information and applications, and the privacy of patients. The crucial part of the act comprises its privacy and security regulations. Privacy regulations address the patients’ rights to understand and control the use of their protected health information. Security regulations can be defined by requirement standards and specifications on what to do and how to do it. For constructing a secure medicine environment, satisfying both privacy and security rules are important.