In LoadRunner, SSL certificates are used to establish secure connections between the client and server. However, sometimes the certificate format provided by the server may not be compatible with LoadRunner. In such cases, it becomes necessary to convert the certificate format to a compatible one. This article focuses on converting .cer format to .pem format in LoadRunner.

Understanding the difference between .cer and .pem formats

Before we dive into the conversion process, let’s first understand the difference between .cer and .pem formats. .cer files are usually in binary DER format, while .pem files are in ASCII format. In simple terms, .cer files are encoded in binary format, while .pem files are encoded in text format. LoadRunner accepts SSL certificates in .pem format.


To convert .cer to .pem format, you need the OpenSSL library installed on your machine. OpenSSL is a robust, full-featured open-source toolkit implementing the Secure Sockets Layer (SSL) and Transport Layer Security (TLS) protocols.

To install OpenSSL on your machine, follow the instructions provided in the OpenSSL website.

Converting .cer to .pem

To convert .cer to .pem, follow the steps given below:

  1. Open a command prompt and navigate to the folder where the .cer file is located.
  2. Type the following command to convert the .cer file to .pem format: openssl x509 -inform der -in certificate.cer -out certificate.pem
  3. Replace “certificate.cer” with the name of your .cer file, and “certificate.pem” with the name you want to give to the converted .pem file.
  4. Press enter to execute the command. Once the conversion is complete, you will see the new .pem file in the same folder where the .cer file is located.


  • Always make a backup of the original .cer file before converting it to .pem format.
  • Ensure that the OpenSSL library is installed and configured correctly before attempting to convert the certificate.

How to Install OpenSSL

To install OpenSSL, follow the steps given below:

  1. Go to the OpenSSL website and download the latest version of OpenSSL for your operating system.
  2. Run the installer and select the components you want to install.
  3. Follow the on-screen instructions to complete the installation process.

Once OpenSSL is installed on your machine, you are ready to convert .cer to .pem format.

Common Errors

During the conversion process, you may encounter some errors. Some of the common errors and their solutions are listed below:

  1. “unable to load certificate” – This error occurs when OpenSSL is unable to read the .cer file. Ensure that the file path and name are correct.
  2. “unable to write certificate” – This error occurs when OpenSSL is unable to write the .pem file. Ensure that you have write permissions for the folder where the .cer file is located.

Further Reading

If you want to learn more about SSL certificates and how they work, check out the following resources:

  1. “SSL Certificates: What Are They and Why Are They Important?” – A comprehensive guide to SSL certificates.
  2. “How to Generate SSL Certificates with OpenSSL” – An in-depth tutorial on how to generate SSL certificates using OpenSSL.
  3. “SSL/TLS Best Practices” – A collection of best practices for SSL/TLS configuration.

FAQs: Convert cer to pem in LoadRunner

What is a CER file?

A CER file is a digital certificate that contains information about the certificate owner, such as their name and public key. It is commonly used for secure communication over the internet, such as in HTTPS connections.

What is a PEM file?

A PEM file is a container format for storing digital certificates and private keys. It is an open standard and can be used in a variety of applications, such as web servers or email clients. PEM files can contain either a single certificate or a chain of certificates.

Why would I need to convert a CER file to a PEM file in LoadRunner?

LoadRunner is a performance testing tool that can simulate HTTP/HTTPS traffic. In order to record HTTPS traffic, you need to install a digital certificate on your LoadRunner machine. The certificate needs to be in PEM format for LoadRunner to recognize it. If you have a CER file, you will need to convert it to PEM format before installing it on your LoadRunner machine.

How can I convert a CER file to a PEM file in LoadRunner?

LoadRunner does not have a built-in tool for converting CER files to PEM files. However, you can use an external tool, such as OpenSSL, to perform the conversion. To do this, you will need to have OpenSSL installed on your machine and have access to the command line. The command to convert a CER file to PEM format is:

openssl x509 -inform DER -in certificate.cer -out certificate.pem -outform PEM

Replace “certificate.cer” with the name of your CER file and “certificate.pem” with the name you want to give your PEM file.

Are there any precautions I should take when converting a CER file to a PEM file?

Yes, it is important to ensure that the certificate you are converting is valid and not expired. Additionally, if the certificate was issued by a trusted Certificate Authority (CA), you should verify the CA’s signature before installing the certificate on your LoadRunner machine. Finally, keep in mind that PEM files can include private keys, and it is important to keep these keys secure and protected.