Convert .p12 bundle to server certificate and key files for Nginx

SSL certificate is a must for nowadays e-commerce site whereas newly emerged web server like Nginx has gained so much attention due to its performance when dealing with heavy traffic to the web site. Why do those people choose Nginx?

Nginx's unique architecture makes it easy to handle large number of concurrent connections at one time with low CPU and memory consumption, compared with IIS and Apache.

Nginx has also taken the place as the front-end proxy server for traditional web servers like IIS and Apache.

Now, back to the topic we are facing today.

Assuming you have received .p12 file from your trust provider, you might need to know more about what a .p12 file is.

According to wiki, PKCS #12 defines an archive file format for storing many cryptography objects as a single file. It is commonly used to bundle a private key with its X.509 certificate or to bundle all the members of a chain of trust.

This means a .p12/.pfx file contains everything we need to provide SSL services, like server certificates, CA root certificate, intermediate chain certificates and server private key.

Unlike .pem file, .p12/.pfx file is in binary form so we cannot copy and paste those blocks for use in a human readable format. It needs a conversion tool like openssl to extract necessary files for the web server like Nginx.

Nginx is also sensitive to the order of server certificate and other CA root and chain certificates in a bundle .pem file so it may not start up properly with a .pem file which has been tempered with no proper knowledge.

Here're the two commands to generate necessary certificate bundle and server key files from a .p12/.pfx bundle file which is supposed to be directly imported into IIS web erver.

#
#
#Generate certificates bundle file
> openssl pkcs12 -nokeys -in server-cert-key-bundle.p12 -out server-ca-cert-bundle.pem
#
#
#Generate server key file
> openssl pkcs12 -nocerts -nodes -in server-cert-key-bundle.p12 -out server.key
#
#

whereas you might be asked to input the password which was included in .p12 file during the creation.

In Niginx.conf, we can include these two files for SSL connection:

#
#
server {
        listen   443 default ssl;
        server_name  localhost ...;

        ssl                  on;
        ssl_certificate      /some_where/ssl_cert/server-ca-cert-bundle.pem;
        ssl_certificate_key  /some_where/ssl_cert/server.key;

        ssl_session_timeout  5m;

        ssl_protocols  SSLv2 SSLv3 TLSv1;
        ssl_ciphers  HIGH:!aNULL:!MD5;
        ssl_prefer_server_ciphers   on;
    
#...  
#

After that, Nginx should start up properly with HTTPS protocol ready for the web site.