create a .pem file for SSL Certificate_pem file multiple certificates-优快云博客

本文链接：https://blog.youkuaiyun.com/peterwin702/article/details/116274600

PEM文件是用于证书安装的证书容器，常用于导入多个构成完整链的证书。它包括可能包含私钥、公钥和根证书的层叠证书。本文介绍了如何使用openssl命令创建自签名PEM文件，以及如何从现有证书文件中构建PEM文件链，包括移除私钥密码和合并不同层级的证书。

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Privacy Enhanced Mail (PEM) files are concatenated certificate containers frequently used in certificate installations when multiple certificates that form a complete chain are being imported as a single file. They are a defined standard in RFCs 1421 through 1424. They can be thought of as a layered container of chained certificates. A .pem file is a container format that may just include the public certificate or the entire certificate chain (private key, public key, root certificates):

Private Key
Server Certificate (crt, puplic key)
(optional) Intermediate CA and/or bundles if signed by a 3rd party

How to create a self-signed PEM file

openssl req -newkey rsa:2048 -new -nodes -x509 -days 3650 -keyout key.pem -out cert.pem

How to create a PEM file from existing certificate files that form a chain

(optional) Remove the password from the Private Key by following the steps listed below:
```
openssl rsa -in server.key -out nopassword.key
```
Note: Enter the pass phrase of the Private Key.
Combine the private key, public certificate and any 3rd party intermediate certificate files:
```
cat nopassword.key > server.pem
cat server.crt >> server.pem
```
Note: Repeat this step as needed for third-party certificate chain files, bundles, etc:
```
cat intermediate.crt >> server.pem
```