Converting Certificate Files to PEM and Key

Certificate files come in different formats, and sometimes it can be a challenge to work with them. The process of converting certificate files to PEM and Key is essential in ensuring that the certificate can be used on different platforms. In this article, we will look at the steps involved in converting certificate files to PEM and Key, and the tools that can be used to simplify the process.

Understanding Certificate Files

Before we delve into the process of converting certificate files, it is essential to understand what certificate files are. A certificate file is a file that contains information about a user, device, or server. The information contained in the certificate file includes the name of the entity, the public key of the entity, and the digital signature of the certificate authority that issued the certificate.

Different Certificate Formats

Certificate files come in different formats, including .pem, .cer, .jks, .pfx, .der, .p12, .crt, and .p7b. Each of these formats has its unique characteristics and is used in different scenarios. For instance, the .pem format is commonly used in Linux, while the .pfx format is used in Windows.

What is PEM and Key?

PEM and Key are formats that are used to store and transport certificate files. PEM is a base64 encoded format that uses headers and footers to differentiate between different types of data. Key, on the other hand, is a binary format that contains the private key of the certificate.

There are different ways of converting certificate files to PEM and Key. However, the most common method is to use OpenSSL, an open-source tool that is available on different platforms. The following are the steps involved in converting certificate files to PEM and Key using OpenSSL.

One key takeaway from this text is the importance of converting certificate files to PEM and Key formats in order to ensure they can be used on different platforms. OpenSSL is a powerful tool that can be used to convert certificate files to these formats, but there are also online and GUI-based certificate conversion tools available for those who prefer a simpler approach. Certificate management tools can also be useful for organizing and managing certificate files.

Step 1: Install OpenSSL

The first step in converting certificate files to PEM and Key using OpenSSL is to install OpenSSL on your machine. OpenSSL is available for different platforms, including Windows, Linux, and macOS. You can download OpenSSL from the official website and follow the installation instructions.

Step 2: Convert the Certificate File to PEM

Once you have installed OpenSSL, the next step is to convert the certificate file to PEM format. To do this, you need to run the following command:

openssl x509 -inform <format> -in <certificate-file> -outform pem -out <certificate-file>.pem

Replace <format> with the format of the certificate file you want to convert, <certificate-file> with the name of the certificate file, and <certificate-file>.pem with the name of the output file.

Step 3: Convert the Certificate File to Key

The next step is to convert the certificate file to Key format. To do this, you need to run the following command:

openssl rsa -inform <format> -in <certificate-file> -outform pem -out <certificate-file>.key

Replace <format> with the format of the certificate file you want to convert, <certificate-file> with the name of the certificate file, and <certificate-file>.key with the name of the output file.

Step 4: Verify the PEM and Key Files

Once you have converted the certificate file to PEM and Key formats, you need to verify that the files are valid. To do this, you can use the following commands:

openssl x509 -noout -text -in <certificate-file>.pem

openssl rsa -noout -text -in <certificate-file>.key

Replace <certificate-file>.pem with the name of the PEM file and <certificate-file>.key with the name of the Key file.

Generate a new private key

openssl genpkey -algorithm RSA -out <private-key-file>.key -aes256

This command generates a new RSA private key and encrypts it with AES-256. Replace <private-key-file>.key with the name of the output file.

Generate a new certificate signing request (CSR)

openssl req -new -key <private-key-file>.key -out <csr-file>.csr

This command generates a new certificate signing request using the private key specified by <private-key-file>.key and saves it to <csr-file>.csr.

Sign a certificate with a CA

openssl x509 -req -in <csr-file>.csr -CA <ca-certificate-file>.pem -CAkey <ca-private-key-file>.key -out <signed-certificate-file>.pem -days 365

This command signs a certificate signing request using the CA certificate and private key specified by <ca-certificate-file>.pem and <ca-private-key-file>.key, respectively. The signed certificate is saved to <signed-certificate-file>.pem and is valid for 365 days.

Verify a certificate chain

openssl verify -CAfile <ca-certificate-file>.pem -untrusted <intermediate-certificate-file>.pem <certificate-file>.pem

This command verifies the certificate chain of a certificate file using the CA certificate and intermediate certificate specified by <ca-certificate-file>.pem and <intermediate-certificate-file>.pem, respectively. Replace <certificate-file>.pem with the name of the certificate file to be verified.

Tools for Simplifying Certificate Conversion

While OpenSSL is a powerful tool for working with certificate files, it can be challenging to use for beginners. Fortunately, there are different tools that can simplify the process of converting certificate files to PEM and Key formats. The following are some of the most popular tools:

Online Certificate Conversion Tools

There are different online tools that can be used to convert certificate files to PEM and Key formats. These tools usually require you to upload the certificate file and then select the output format. Some popular online certificate conversion tools include SSLShopper, SSL2BUY, and DigiCert.

GUI-based Certificate Conversion Tools

If you prefer to use a graphical user interface (GUI) instead of the command line, there are different GUI-based certificate conversion tools available. These tools allow you to convert certificate files to PEM and Key formats by simply selecting the input file and the output format. Some popular GUI-based certificate conversion tools include OpenSSL GUI, KeyStore Explorer, and XCA.

Certificate Management Tools

If you work with certificate files frequently, you might find it useful to use a certificate management tool. These tools allow you to manage and organize your certificate files, as well as perform different operations on them, such as converting them to different formats. Some popular certificate management tools include KeyHub, CertCentral, and ManageEngine Key Manager Plus.

FAQs for Convert Cert to PEM and Key

What is a PEM file?

A PEM file is a type of file format commonly used in the context of SSL/TLS certificates. PEM stands for “Privacy Enhanced Mail” but is now widely used to refer to any base64-encoded file containing certificate data. It often contains both the certificate and associated private key within the same file.

How do I convert a certificate to PEM format?

To convert a certificate to PEM format, you can use the OpenSSL command-line tool. The command would typically look something like this:

“`
openssl x509 -in input-cert.crt -out output-cert.pem -outform PEM

This command takes an input certificate in X.509 format, specified by the -in option, and converts it to the PEM format. The resulting output is written to a file specified by the -out option.

How do I convert a private key to PEM format?

You can also use the OpenSSL tool to convert a private key to PEM format. The command would typically look something like this:

openssl rsa -in input-key.key -out output-key.pem -outform PEM

This command takes an input private key in RSA format, specified by the -in option, and converts it to the PEM format. The resulting output is written to a file specified by the -out option.

How do I combine a certificate and private key into a single PEM file?

To combine a certificate and private key into a single PEM file, you can use a text editor to copy and paste the contents of the certificate file and key file into a new blank file. The order should be as follows:

—–BEGIN CERTIFICATE—–
[certificate data]
—–END CERTIFICATE—–
—–BEGIN PRIVATE KEY—–
[private key data]
—–END PRIVATE KEY—–

Save the file with a .pem extension, and you now have a new PEM file containing both the certificate and private key.

Can I convert a PEM file back to X.509 format?

Yes, you can use the OpenSSL tool to convert a PEM file back to X.509 format. The command would typically look something like this:

openssl x509 -in input-cert.pem -out output-cert.crt -outform der

This command takes an input PEM file, specified by the -in option, and converts it back to X.509 format. The resulting output is written to a file specified by the -out option.