Understanding certificate formats

Before we dive into the conversion process, let’s understand the difference between CRT and PEM certificate formats. CRT (or CER) is a binary format used for storing X.509 certificates. PEM, on the other hand, is a base64-encoded format that includes header and footer lines.

Why convert to PEM?

PEM format is widely used and supported by most modern systems. It is also easier to read and manipulate compared to the binary CRT format. Converting your certificate to PEM can therefore be useful in many situations.

Steps to convert CRT to PEM

The following steps assume you have OpenSSL installed on your system. If not, you can install it using your system’s package manager.

Step 1: Create a backup

Before you begin the conversion process, it’s always a good idea to create a backup of your original certificate. This ensures you can revert to the original state in case something goes wrong.

Step 2: Convert the certificate

To convert your certificate from CRT to PEM format, use the following command:


This command reads the input certificate file certificate.crt and writes the output to certificate.pem in PEM format.

Step 3: Verify the output

Once the conversion is complete, you can verify the output using the following command:

This command displays the contents of the PEM file in human-readable format and ensures that the conversion was successful.

FAQs – Convert CRT Certificate to PEM Format

What is a CRT certificate?

A CRT (Certificate) is a digital certificate file that is used to establish a secure and encrypted connection between a server and a client. Typically, they are used to secure websites, email servers, and other network services. The certificate contains information about the server, its public key, and the certificate’s expiration date.

Why convert a CRT certificate to a PEM format?

PEM (Privacy Enhanced Mail) is another digital certificate format. It is widely used in the Linux and UNIX operating systems. Converting a CRT certificate to PEM format allows you to use the certificate in systems that only accept PEM format certificates.

How can I convert a CRT certificate to PEM format?

There are many ways to convert a CRT certificate to PEM format. The most common method is to use OpenSSL, an open source cryptography toolkit that is available for many operating systems. The command line syntax to convert the CRT certificate to PEM format is as follows:

openssl x509 -in certificate.crt -out certificate.pem -outform PEM

Can I convert multiple CRT certificates to PEM format at once?

Yes, you can convert multiple CRT certificates to PEM format at once by using a wildcard character (*) in the file path. For example, if you have three certificates named certificate1.crt, certificate2.crt, and certificate3.crt, you can convert them to PEM format using the following command:

openssl x509 -in certificate*.crt -outform PEM -out certificates.pem

Does the conversion process affect the security level of my certificate?

No, the conversion process does not affect the security level of your certificate. It simply changes the format of the certificate from CRT to PEM. The security of the certificate is determined by the certificate issuer and the encryption algorithm used in the certificate.

Where can I use my certificate after converting it to PEM format?

You can use your certificate in any system that supports PEM format certificates, including Linux and UNIX operating systems. PEM format certificates are also supported by many programming languages, including JavaScript, Python, and Ruby, so you can use your certificate in your web or application development projects.