隨著醫療資訊的電子化與網路發展，醫師們得以藉由遠距醫療會診系統突破地理限制而共同進行病情的討論。但是在網路傳遞個人的醫療隱私會有被他人擷取的風險。由於醫療資訊具相當高的敏感性，若在進行遠距會診時不能提供適當的保護措施，不但會因此降低病患對醫療機構的信任，更有可能會延誤了就醫的時機。
　　在本篇論文中，利用Kerberos 認證協定與對稱式加密，針對一個遠距醫療會診系統的運作設計了一套安全機制，包含能夠在每次通訊連線建立時驗證雙方的身份，並且使得每次的通訊內容受到加密的保護。此外為了讓使用者能透過網頁瀏覽器進行遠距會診時提供身份認證，亦提出了透過http連線實現使用Kerberos進行登入時身份驗證方法。然而，因為會診進行時所有的通訊內容必須由伺服器加密後傳送給所有參與者，若每一個參與會診的人皆使用不同的金鑰進行加密運算便會影響會診進行時伺服器的效能，為此我們提出了一個會議金鑰的發送方法(Conference Key Distribution, CKD)，讓同一會診中的所有參與者能使用相同的金鑰進行加解密，以降低伺服器的運算負擔。

　　With the medical record digitalization and network development, doctors can take advantage of participating in Teleconsultation to discuss patient’s syndrome, overcoming the geographic distance. But meanwhile it also implicates that the personal medical privacy would be transmitted on a public network. If we cannot provide proper protection for the Medical Data Transmission, consequently it would lower the trust of both patients and doctors to this system.
　　In this thesis, utilizing Kerberos Authentication and Symmetric-key Cryptography, we design a security mechanism for a Web-based Medical Teleconsultation System, which includes Authentication and Cryptographic Key Exchange to ensure that transmission session in the teleconsultation is authorized and protected by encryption. In order to enable physicians accessing teleconsultation system through web browser, we design a login certification mechanism over HTTP fulfilled with Kerberos. Besides, to avoid the affection from encryption/ decryption with different key during a teleconsultation, this might sap the server’s efficiency. Therefore, we design a Conference Key Distribution (CKD) procedure, which allows all participants in the same teleconsultation using the same Key for encryption/ decryption in order to ease the server’s load.

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[8]　J. Wray, "Generic Security Service API Version 2 : C-bindings", IETF RFC 2744, Jan 2000.
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