openssl pkcs12 -in [yourfile.pfx] -nocerts -out [keyfile-encrypted.key]
What this command does is extract the private key from the .pfx file. Once entered you need to type in the importpassword of the .pfx file. This is the password that you used to protect your keypair when you created your .pfx file. If you cannot remember it anymore you can just throw your .pfx file away, cause you won’t be able to import it again, anywhere!. Once you entered the import password OpenSSL requests you to type in another password, twice!. This new password will protect your .key file.
Now let’s extract the certificate:
openssl pkcs12 -in [yourfile.pfx] -clcerts -nokeys -out [certificate.crt]
Just press enter and your certificate appears.
Now as I mentioned in the intro of this article you sometimes need to have an unencrypted .key file to import on some devices. I probably don’t need to mention that you should be carefully. If you store your unencrypted keypair somewhere on an unsafe location anyone can have a go with it and impersonate for instance a website or a person of your company. So always be extra careful when it comes to private keys! Just throw the unencrypted keyfile away when you’re done with it, saving just the encrypted one.
The command:
openssl rsa -in [keyfile-encrypted.key] -out [keyfile-decrypted.key]
Again you need to enter an import password. This time you need to enter the new password that you created in step 1. After that you’re done. You decrypted your private key. In the folder you ran OpenSSL from you’ll find the certifcate (.crt) and the two private keys (encrypted and unencrypted).
Ref: https://www.markbrilman.nl/2011/08/howto-convert-a-pfx-to-a-seperate-key-crt-file/
Ref: https://aws.amazon.com/blogs/security/how-to-import-pfx-formatted-certificates-into-aws-certificate-manager-using-openssl/#:~:text=To%20import%20the%20certificates,Select%20Import%20a%20certificate.
