Hint for Waldo

Im suck and not sure what is wrong. I got the m****** file and put it though sed to strip out everything bad, but then I try to ssh n****y@10.10.10.87 and I am getting “Permissions 0644 for ‘********.key’ are too open.
It is required that your private key files are NOT accessible by others.
This private key will be ignored.”

Can anyone give me a hint as to where I have gone wrong?