I have a pem file that looks like the one in SSHJ tests (though I don\'t see it being referenced): https://github.com/shikhar/sshj/blob/master/src/test/resources/hostkey.pem
It's not the user authentication that's tripping you, it's the host key verification :)
Something like client.addHostKeyVerifier("xx:0a:xx:b5:c2:fd:44:1d:e0:e4:fc:xx:5f:f8:dd:f6") before connecting.