If you generate a key pair with ssh-keygen you can, depending on version, get a private key with the header
-----BEGIN OPENSSH PRIVATE KEY-----
This type of key is not compatible with f.ex. jsch and needs to be converted so that it has the header
-----BEGIN RSA PRIVATE KEY-----
They way to convert existing keys is as follows:
ssh-keygen -p -m PEM -f yourkeyfile
This command is for setting a new passphrase for your private key, but since the -m PEM
flag is there it will write the key in the classic format.
---- BEGIN SSH2 PUBLIC KEY ----
Comment: "rsa-key-20240814"
AAAAB3NzaC1yc2EAAAADAQABAAABAQCw3/7SIkqsM0kOBfn8wUrPD+NrtDNnE0VT
2jFHi9h6XU6xqbMp5XKPFrlD/MQKbpmaZZBbMvQsYww3DJ6G2uA9GY8xK0XseGmq
vfMbnI2mMZ73NzD655oYfyWlTrboXcvQMNzratSd4zkgIuiRT4hhB2Q3/g/30z6h
3qLhyXQvHRrML7Jj69twad1A9P2ak6iBUNFiBkMMpqu+RVVmiMjFgaAM5uCPZWqw
CC0LGel5I7lJ6ZVnNDwxkJjBCN5JJU6dBQoUSDQUoVbKA8o/Wlys0cvyxWdsNNV0
b+NrBAgI6cNw6UAu52W48Wir1QMEQFAA5rjhk7x1OHQV0Y0e7DM5
---- END SSH2 PUBLIC KEY ----