Different types of SSH keys - zelent.net
https://zelent.net/blog/ssh-keys20.07.2021 · This is a non-standard private key format developed by the OpenSSH team. It doesn't have much in common with the PKCS keys, as it is constructed in a different way than them. It is however the default format for ssh-keygen. It is preferred by OpenSSH because it is supposedly more secure and allows for comments in the key.