20 October 2020

We found we needed to change some certificate formats at work to support a specific 3rd party. Googling found this excellent cheat-sheet for working with openssl: https://www.sslshopper.com/article-most-common-openssl-commands.html

There’s a lot of useful stuff here, ones we needed were:

Check if one of our private keys was in a compatible format

openssl rsa -in privateKey.key -check

It wasn’t - we used PuttyGen to export as a SSL format pem file private key.

 Actions -> Load Key
 Converstions (Menu) -> Export OpenSSH Key

Generate the matching public key in SSL format:

openssl rsa -in key.pem -pubout -out pubkey.pem