雲端儲存系統中個人健康紀錄之安全存取控制-使用屬性加密機制

Abstract

Personal Health Record (PHR)是一種醫療資訊紀錄，其來源包含病人紀錄的個人健康資訊如飲食型態、家族病史、醫生處方籤等，由病人所擁有並且管理。近年來雲端技術的蓬勃發展，各式各樣的雲端應用服務應運而生，其中雲端儲存系統提供了使用者便利的資料儲存服務，而病人將PHR存放在雲端儲存系統帶來了許多好處，像是有利於他集中管理、節省儲存空間以及方便分享給其他使用者，然而此種做法卻衍生了新的問題：病人要如何對儲存在雲端的PHR達到安全的存取控制？一旦病人將儲存PHR的任務交由雲端儲存服務供應商幫忙處理，病人便無法即時監控他的PHR是否遺失抑或是遭到竊取甚至濫用。換句話說，雲端儲存服務供應商並不保證PHR的是否被安全存取以及PHR的隱密性，病人的隱私資料未得到妥善的保護。在與其他使用者共享PHR的部分，病人對其PHR理應擁有絕對的控制權，要如何讓病人能夠針對不同層級的使用者給予相對的權限來存取他的PHR亦是一個重要的議題。因此，在病人將PHR存放在雲端儲存系統之前，需要透過一套安全且有效率的加密技術用以保護病人的隱私不致洩漏，本篇研究提出一個PHR系統的框架，利用Decentralizing Attribute-Based Encryption (DABE)的技巧來加密病人的PHR，達成在雲端儲存服務上，對PHR安全的存取控制與共享的目標，進而提升對病人隱私資料的保護。而我們所提出的框架也會滿足細粒度存取控制、資料隱私與可拓展性等安全需求。最後我們實作了一個雲端化的PHR系統，展示我們的系統是可行的。

Personal Health Record (PHR) is an information related to the care of a patient himself and is maintained and managed by patient. PHR contains variety of health data such as a patient’s diet, family history, and prescription record etc. Nowadays with the emergence of cloud computing, many cloud services are provided, including the cloud storage which enables people to store and manage their data in remote storage conveniently. Deploying cloud computing platform in PHR system is not only inexpensive but also provides wide-area access and large storage capability for a patient, who can control and share his PHR with other people. However migrating PHR to cloud storage incurs new security problem: how does patient enforce secure access control of his PHR? Although cloud delivers many resources as a service, unfortunately it also gives attackers new possibilities to launch attacks. On the other hand, cloud service provider does not promise the security and confidentiality of PHR. Besides, patient may share his PHR with many people under different access policy. Therefore, we propose a framework of PHR system, which leverages Decentralizing Attribute-Based Encryption (DABE) to encrypt PHR and enforce access control policy. This framework satisfies several security properties such as fine-grained access control, data privacy and scalable access. And we implement a PHR system to display that this system is effective.