由于项目中需要使用https数字证书，搜索了一大圈，不是收费就是步骤繁琐，最后发现let encrypt是个不错的免费站点。

官网：Let's Encrypt

加密申请地址：来此加密 - Let's Encrypt 在线免费申请SSL证书

使用说明：平台介绍 · 语雀

文档下载地址：https://www.abetterinternet.org/documents/letsencryptCCS2019.pdf

以下引用官网的介绍：

Let's Encrypt 主要原则

Let's Encrypt is a free, automated, and open Certificate Authority.

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.