Digital security has top priority in the modern world of information technology, especially in web development and IT infrastructure. A key element of this security is the use of certificates and keys for identification and encryption. The PEM format is one of the most common formats used in this domain. But why is that? And how can you convert RSA keys to PEM format? In this post, we'll shed light on exactly that.

What is the PEM Format?

PEM stands for "Privacy Enhanced Mail" and was originally developed for adding encryption to emails. Nowadays, however, it is far more widespread as a standard format for certificates and keys in IT.

Apache servers, one of the most widely used web server software solutions worldwide, as well as many other servers and systems, use the PEM format for certificates. A main reason is its versatility: the PEM format can store both the certificate and the associated private key in the same file.

Likewise, identifying PEM files is quite simple, as they typically end with the suffixes .pem, .crt, .cer, and .key. These extensions provide a hint about the content of the file, even though all actually use the same base format.

Converting RSA Keys to PEM Format

It's possible that you already have RSA keys that you need to convert to PEM format, especially if you're switching from another system or format. The conversion process is simple and straightforward thanks to the openssl tool.

Use the following command to convert an existing RSA key to PEM format:

openssl rsa -in ~/.ssh/id_rsa -outform pem > id_rsa.pem

In this command:

  • openssl rsa: The command uses the rsa module from OpenSSL.
  • -in ~/.ssh/id_rsa: This specifies the path of the existing RSA key.
  • -outform pem: This specifies the desired output format, in this case PEM.
  • > id_rsa.pem: Here the output is redirected to a file named "id_rsa.pem".

After you've executed this command, the RSA key should have been successfully converted to a PEM file.

Conclusion

Converting RSA keys to PEM format is child's play thanks to tools like openssl. Since many systems and servers, including Apache, use the PEM format, it's important to become familiar with handling and converting certificates and keys in this format. With the knowledge above, you're well equipped to manage your RSA keys securely and effectively.