传统的身份认证方法，主要包括个人密码，身份证，钥匙等，其安全性和使用方便性都越来越不能满足现代社会的需要。
The conventional personal identification methods, e. g. personal password, identity card, and key, are not satisfied to the need of modern society in security and convenience.
VPN密码系统的构建涉及几个方面的技术，包括加密技术、认证技术、实现协议等。
VPN cryptographical system is concerned with cryptographical technology, authentication technology and VPN implementation protocols.
论文的主要工作包括以下几个方面：1身份认证的密码学理论基础分析。
The contributions of the dissertation are as follows. 1 Cryptology is the foundation of authentication.
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