- 學位論文
基於無線區網之 Ad Hoc 群組通訊
Ad Hoc Group Communication Based on Multicast in Wireless LAN
摘要
隨著近年來資通訊科技的快速發展，行動裝置已成為人們生活中不可或缺的重要一環，更因為無線網路的普及，各種需要連網的應用程式隨之而起，而其中則以即時通訊軟體最為人們所依賴，多數人們生活中與人溝通的部分逐漸地被通訊軟體所取代，如 LINE、Facebook Messenger、WhatsApp 等，甚至改變了人與人之間的互動模式。然而若身處於對外網路沒法正常運作亦或是無法接收電信基地台訊號之處，這些即時通訊軟體則無法正常運作，將導致資訊傳遞上的困難甚至因此使得人們因為無法溝通而感到焦慮。此外，近年來使用者對於通訊隱私及安全性有所疑慮，因此通訊軟體之設計應考量如何降低通訊安全風險。本研究透過網路群播 (IP Multicast) 的技術實作一運作於無線區網中且同時支援 iOS 與 Android 雙系統的去中心化通訊軟體，藉由網路群播與去中心化的特性，使用者間自然形成出一 隨意形成的Ad Hoc 群組，並且本系統處於無對外網路的惡劣環境依然能正常運作，也因此減少了封包在外網被竊聽的可能性，並且不需要承擔中央伺服器資料保存上的風險。此外，在通訊過程中訊息皆被加密，而加密金鑰將被繪成 QR Code 讓使用者在現實中掃描來進行密鑰交換，除了簡化密鑰交換的複雜流程之外也降低了密鑰外洩的風險。
並列摘要
Along with the fast development of ICT, mobile devices have become indispensable in daily life. As wireless networks are available everywhere, a variety of networked applications are deployed and widely used. Among them, instant messaging software, e.g LINE, Facebook Messenger, and WhatsApp, are most popular and become the major tool of personal communication. However, when the public Internet are not accessible in case of the failure of base stations, those instant messaging applications will not work properly. In addition, in the recent years, users start to worry about security and privacy in using these communication software, including the protection of data during communication and the storage in servers. Therefore, a good design of personal communication software should take into account possible security risk. In this study, we propose a de-centralized instant messaging application based on IP Multicast in both iOS and Android systems. This application allows the users to form ad hoc groups for personal communication even when the public network is not accessible. As a result, eavesdropping from the public network is impossible. Furthermore, the application doesn’t need a central server for data storage. The risk of data leakage can be reduced. In the proposed implementation, data communication is encrypted and the secret key for encryption is shared via a QR code as users face each other. Consequently, secret key can be protected effectively.