Unimus supports SSH private keys in the following formats:

 rsadsaecdsaed25519
PEMyesyesyesno
PKCS8yesyesnono
OpenSSH
(RFC4716)
nononono

Different versions of ssh-keygen (OpenSSH) use different default key types and formats across the different OpenSSH versions.

If your SSH key is not being properly loaded by Unimus, you can easily use OpenSSH to transform key formats. This command will transform an OpenSSH private key into a PEM encoded key:

ssh-keygen -e -f /path/to/openssh.key -m PEM > /path/to/new_pem.key

-e read OpenSSH formatted key
-f from file
-m export format