針對以為基礎之臨界密碼系統的有效安全廣播模組

Abstract

本篇論文主要是針對在無線網路上，以PHF(Perfect Hash Family)為基礎的臨界(threshold)密碼系統，在安全廣播(broadcast)上面的特定需求，所設計的一個解決方案。 以PHF為基礎的臨界密碼系統有一個特色，即是各個user可由其所分享到的share，來組成不同的group。在這樣的觀點下，group與group間的安全傳輸以及各個group內部的安全傳輸，便是一個需要解決的問題。如果這個問題能夠解決，那麼將可以用作share renewal等方面的應用。並且，考量無線網路傳輸上的特性，若是能以廣播的方式來做安全的傳輸，那麼將可以大量的減少所需要的傳輸量。 [1]提到了一個一般化的安全廣播模組，它需要一個TA(trust authority)來做pre-key的分配。然而，在某些無線網路架構上(舉例:Mobile Ad-hoc Network[2])，假設TA的存在往往有些不切實際。因此，在這篇論文中，我們提出了一個針對以PHF為基礎之臨界密碼系統的安全廣播模組，它不需要任何TA，並且，於安全廣播時所需要的訊息傳輸量也較[1]來的少。

The thesis targets for the particular requirement of secure broadcast on PHF (Perfect Hash Family)-based threshold cryptosystems on wireless networks, and we propose a method for doing such secure broadcast. There is a property on PHF-based threshold cryptosystems: The users in the system can be partitioned into groups by the shares they keep. In such perspective, the secure communication between groups and within groups will be an issue which is needed to be solved. If such issue has been solved, then we can play applications of "share renewal", etc. Moreover, consider the native property of communication on a wireless network. If we apply broadcast technique, then we can reduce the communication cost greatly. The paper in [1] gave a general secure broadcast scheme. It needs a TA (trust authority) to do the distributions of pre-key. However, in some wireless networks (Ex:Mobile Ad-hoc Network[2]), the existence of a TA is not practical at all. In the thesis, we propose a secure broadcast model on PHF-based threshold cryptosystems. It needs not a TA, and also, the communication cost while doing secure broadcast is less than [1].