適用電子商務環境之金鑰恢復與託管機制

Abstract

在電子商務環境中，一個安全的交易環境是不可或缺的，而安全的密碼系統正提供我們一個很好的解決方案。本研究所要探討的課題即是密碼系統中的金鑰恢復與金鑰託管機制。由於金鑰恢復與金鑰託管機制之運作需要繁複的金鑰運算與訊息傳遞。而本研究提出之金鑰恢復與託管機制，利用橢圓曲線密碼系統中金鑰長度較短與計算速度快之優點，以及自我認證公開金鑰密碼系統中有效率的驗證公鑰正確性之優點，讓此機制不必依靠系統中心就能達到身份確認以及提高效率性。另外我們在電子現金系統中加入託管的功能，設計出託管電子現金系統，避免電子現金完全匿名可能產生之犯罪行為，我們所設計的託管電子現金系統除了具有防範網路犯罪之功能（如洗錢、勒索），並且能迅速地找出犯罪者，還給受害者一個公道。It is essential to have secure transactions in an electronic commerce environment. To ensure the security of electronic transactions, a good cryptosystem is required for providing a solution. In the cryptosystems, the security depends on the key management is a very important issue to the cryptosystems. This paper is to research on the key recovery mechanism (KRM) and key escrow mechanism (KEM) of the cryptosystems. In general, the operations of KRM and KEN are based on complicated key computations and message transmissions. The KRM and KEM proposed in this paper integrate the elliptic curve cryptosystem ECC into the self-certified public key cryptosystem (SCPKC). In the ECC, the length of key is shorter and the calculation of key is faster than other public key cryptosystems like RSA, etc. In the SCPKC, the public key can be validated efficiently and the user can be identified without the assistance of system authority (SA). In the paper, we also develop the escrow electronic cash system by combining the electronic cash system with the key recovery and escrow schemes. The escrow electronic cash system developed can avoid network (e.g. blackmailing and money laundering) arising from the anonymity of electronic cash, and can find criminals immediately when necessary.