Getting Key value does not parse into a valid ssh-rsa key

[rajuec2005]

I launched the spot fleet request where 1 inst is launched and running with keypair xxx .
While configuring the jenkins plugin i selected the
Host Key Verification Strategy as Manually provided Verification Strategy and base 64encoded the RSA private key of xxx and gave as 'ssh-rsa base64encodedprivatekey'

I am getting error 'Key value does not parse into a valid ssh-dss key'