In order to let everyone accept these internet transactions, a useful and safe public key cryptosystem is needed.为了让人能接受以上这些应用在网路交易的形式，一个有效且安全的公开金钥密码系统是非常重要的。
A public-key cryptosystem allows users to communicate securely without having prior access to a shared secret key.公共金钥密码系统可以让用户安全通信，而无需事先获得一个共享密钥。
