When lauching a job, the droplet is created but when the plugin try to connect using ssh key it fails.

AVERTISSEMENT: Publickey authentication failed.
java.io.IOException: Publickey authentication failed.
at com.trilead.ssh2.auth.AuthenticationManager.authenticatePublicKey(AuthenticationManager.java:315)
at com.trilead.ssh2.Connection.authenticateWithPublicKey(Connection.java:467)
at com.dubture.jenkins.digitalocean.ComputerLauncher.launch(ComputerLauncher.java:154)
at hudson.slaves.SlaveComputer$1.call(SlaveComputer.java:253)
at jenkins.util.ContextResettingExecutorService$2.call(ContextResettingExecutorService.java:46)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.io.IOException: Decrypted PEM has wrong padding, did you specify the correct password?
at com.trilead.ssh2.crypto.PEMDecoder.removePadding(PEMDecoder.java:110)
at com.trilead.ssh2.crypto.PEMDecoder.decryptPEM(PEMDecoder.java:287)
at com.trilead.ssh2.crypto.PEMDecoder.decode(PEMDecoder.java:320)
at com.trilead.ssh2.auth.AuthenticationManager.authenticatePublicKey(AuthenticationManager.java:224)
... 8 more

The droplet created is a 512Mo with Ubuntu 16.04, user root using a public key declared in Digital Ocean console.