标签： ssl

Let’s Encrypt  免费，90天有效

The key principles behind Let’s Encrypt are:

Free: Anyone who owns a domain name can use Let’s Encrypt to obtain a trusted certificate at zero cost.
Automatic: Software running on a web server can interact with Let’s Encrypt to painlessly obtain a certificate, securely configure it for use, and automatically take care of renewal.
Secure: Let’s Encrypt will serve as a platform for advancing TLS security best practices, both on the CA side and by helping site operators properly secure their servers.
Transparent: All certificates issued or revoked will be publicly recorded and available for anyone to inspect.
Open: The automatic issuance and renewal protocol will be published as an open standard that others can adopt.
Cooperative: Much like the underlying Internet protocols themselves, Let’s Encrypt is a joint effort to benefit the community, beyond the control of any one organization.

网上有一些教程，大多linux环境下，少部分windows环境。这边主要讲windows环境下的使用。
首先去找一款软件 letsencrypt-win-simple

打开后，大概三个选项，网上教程大多使用M 手动创建，然后使用计划任务定期更新。

此外还有两个选项 webdav和 FTP，我这边使用FTP。这样就可以通过FTP上传和修改他要验证的文件。

在客户端与服务器间传输的数据是通过使用对称算法（如 DES 或 RC4）进行加密的。公用密钥算法（通常为 RSA）是用来获得加密密钥交换和数字签名的，此算法使用服务器的SSL数字证书中的公用密钥。有了服务器的SSL数字证书，客户端也可以验证服务器的身份。SSL 协议的版本 1 和 2 只提供服务器认证。版本 3 添加了客户端认证，此认证同时需要客户端和服务器的数字证书。