An introduction to PKI, TLS and X.509, from the ground up. Public Key Infrastructure (PKI) provides a framework of encryption and data communications standards used to secure communications over public networks. At the heart of PKI is a trust built among clients, servers and certificate authorities (CAs). This trust is established and propagated through the generation, exchange and verification of certificates.

从头开始介绍PKI、TLS和X.509。公钥基础设施（PKI）提供了一个加密和数据通信标准框架，用于保护公共网络上的通信。PKI的核心是客户端、服务器和证书颁发机构（CA）之间建立的信任。这种信任是通过证书的生成、交换和验证来建立和传播的。