SFTP Plugin Issue

We are trying to connect with the SFTP server using public/private keys to avoid using a password.  We are using Send File Over SFTP smart service and we are passing parameters like External System Key, User Per Credentials is set to false, server hostname, server port, remote file path and source document. The third party credential is set to get the external system key value. 

However, we are facing the below mentioned error: 

Error establishing SFTP connection. Confirm your hostname, username and password. See application server log for more details. Error Message: Auth fail]

Could anyone please advice and let me know what's missing?

Thanks,

Sonal

  Discussion posts and replies are publicly visible