Generate Private Key From Crt Openssl

14.12.2020
Generate Private Key From Crt Openssl Rating: 7,9/10 6411 reviews

If you want to convert your website from HTTP to HTTPS, you need to get a SSL certificate from a valid organization like Verisign or Thawte. You can also generate self signed SSL certificate for testing purpose.

In this article, let us review how to generate private key file (server.key), certificate signing request file (server.csr) and webserver certificate file (server.crt) that can be used on Apache server with mod_ssl.

How to Generate & Use Private Keys using OpenSSL's Command Line Tool These commands generate and use private keys in unencrypted binary (not Base64 “PEM”) PKCS#8 format. The PKCS#8 format is used here because it is the most interoperable format when dealing with software that isn't based on OpenSSL. Jun 19, 2015  -inkey privateKey.key – use the private key file privateKey.key as the private key to combine with the certificate.-in certificate.crt – use certificate.crt as the certificate the private key will be combined with.-certfile more.crt – This is optional, this is if you have any additional certificates you would like to include in the PFX file.

Jul 08, 2009  You can also generate self signed SSL certificate for testing purpose. In this article, let us review how to generate private key file (server.key), certificate signing request file (server.csr) and webserver certificate file (server.crt) that can be used on Apache server with modssl. Key, CSR and CRT File Naming Convention. Generate rsa keys by OpenSSL. Using OpenSSL on the command line you’d first need to generate a public and private key, you should password protect this file using the -passout argument, there are many different forms that this argument can take so consult the OpenSSL documentation about that. Openssl genrsa -out private.pem 1024. Common OpenSSL Commands with Keys and Certificates. Generate RSA private key with certificate in a single command openssl req -x509 -newkey rsa:4096 -sha256 -keyout example.key -out example.crt -subj '/CN=example.com' -days 3650 -passout pass:foobar. Oct 15, 2012  Convert from CRT to PFX with openssl In many cases where you need an SSL certificate for your web servers (or other secure services like Lync, Exchange etc) you need to get a digital certificate from a third party certificate authority.

Key, CSR and CRT File Naming Convention

I typically like to name the files with the domain name of the HTTPS URL that will be using this certificate. Avg internet security key code generator. This makes it easier to identify and maintain.

  • Instead of server.key, I use www.thegeekstuff.com.key
  • Instead of server.csr, I use www.thegeekstuff.com.csr
  • Instead of server.crt, I use www.thegeekstuff.com.crt

1. Generate Private Key on the Server Running Apache + mod_ssl

First, generate a private key on the Linux server that runs Apache webserver using openssl command as shown below.

The generated private key looks like the following.

2. Generate a Certificate Signing Request (CSR)

Using the key generate above, you should generate a certificate request file (csr) using openssl as shown below.

3. Generate a Self-Signed SSL Certificate

For testing purpose, you can generate a self-signed SSL certificate that is valid for 1 year using openssl command as shown below.


You can use this method to generate Apache SSL Key, CSR and CRT file in most of the Linux, Unix systems including Ubuntu, Debian, CentOS, Fedora and Red Hat.

4. Get a Valid Trial SSL Certificate (Optional)

Instead of signing it youself, you can also generate a valid trial SSL certificate from thawte. i.e Before spending the money on purchasing a certificate, you can also get a valid fully functional 21 day trial SSL certificates from Thawte. Once this valid certificate works, you can either decide to purchase it from Thawte or any other SSL signing organization.

This step is optional and not really required. For testing purpose, you can always use the self-signed certificate that was generated from the above step.

Go to Thwate trial certificate request page and do the following:

  • Select “SSL Web Server Certificate (All servers)” under the “select your trial certificate”.
  • Do not check the PKCS #7 check-box under the “configure certificate”
  • Copy/Paste the *.csr file that you generate above in the textbox under “certificate signing request (CSR)”
  • Click on next at the bottom, which will give you a 21-day free trial certificate.


Copy/Paste the trial certificate to the www.thegeekstuff.com.crt file as shown below.

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One of the most versatile SSL tools is OpenSSL which is an open source implementation of the SSL protocol. There are versions of OpenSSL for nearly every platform, including Windows, Linux, and Mac OS X. OpenSSL is commonly used to create the CSR and private key for many different platforms, including Apache. However, it also has hundreds of different functions that allow you to view the details of a CSR or certificate, compare an MD5 hash of the certificate and private key (to make sure they match), verify that a certificate is installed properly on any website, and convert the certificate to a different format. A compiled version of OpenSSL for Windows can be found here.

If you don't want to bother with OpenSSL, you can do many of the same things with our SSL Certificate Tools. Below, we have listed the most common OpenSSL commands and their usage:

Generate Private Key From Crt Openssl Mac

General OpenSSL Commands

These commands allow you to generate CSRs, Certificates, Private Keys and do other miscellaneous tasks.

  • Generate a new private key and Certificate Signing Request
  • Generate a self-signed certificate (see How to Create and Install an Apache Self Signed Certificate for more info)
  • Generate a certificate signing request (CSR) for an existing private key
  • Generate a certificate signing request based on an existing certificate
  • Remove a passphrase from a private key

Checking Using OpenSSL

If you need to check the information within a Certificate, CSR or Private Key, use these commands. You can also check CSRs and check certificates using our online tools.

  • Check a Certificate Signing Request (CSR)
  • Check a private key
  • Check a certificate
  • Check a PKCS#12 file (.pfx or .p12)

Debugging Using OpenSSL

If you are receiving an error that the private doesn't match the certificate or that a certificate that you installed to a site is not trusted, try one of these commands. If you are trying to verify that an SSL certificate is installed correctly, be sure to check out the SSL Checker.

  • Check an MD5 hash of the public key to ensure that it matches with what is in a CSR or private key
  • Check an SSL connection. All the certificates (including Intermediates) should be displayed

Converting Using OpenSSL

These commands allow you to convert certificates and keys to different formats to make them compatible with specific types of servers or software. For example, you can convert a normal PEM file that would work with Apache to a PFX (PKCS#12) file and use it with Tomcat or IIS. Use our SSL Converter to convert certificates without messing with OpenSSL.

  • Convert a DER file (.crt .cer .der) to PEM
  • Convert a PEM file to DER
  • Convert a PKCS#12 file (.pfx .p12) containing a private key and certificates to PEM

    You can add -nocerts to only output the private key or add -nokeys to only output the certificates.

  • Convert a PEM certificate file and a private key to PKCS#12 (.pfx .p12)

Generate Private Key From Crt File Openssl

Originally posted on Sun Jan 13, 2008