Bug 681493

Sorry, I know this is the wrong component, but I can't find the right component for reporting ssh problems; I'm hoping you will know how to redirect.

Description of problem:
ssh error messages for changed keys is highly misleading.

Version-Release number of selected component (if applicable):
Any recent

How reproducible:
Always

Steps to Reproduce:
1. ssh to a host whose host key has changed
2.
3.
  
Actual results:
ssh responds:
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that the RSA host key has just been changed.
The fingerprint for the RSA key sent by the remote host is
cc:e5:df:24:f6:1a:b4:dd:7d:61:c0:87:bb:98:80:3b.
Please contact your system administrator.
Add correct host key in /root/.ssh/known_hosts to get rid of this message.
Offending key in /root/.ssh/known_hosts:9
RSA host key for scteach.snu.ac.kr has changed and you have requested strict checking.
Host key verification failed.

This message is effectively useless, as known_hosts is now encrypted by default
so that methods the user is likely to have used for editing it won't work. The hint that the offending key is likely line 9 is too cryptic to be useful (and may be difficult to interpret if there are any comments in known_hosts). In any case, the user has no reasonable way to directly add the correct key, other than by deleting the line and running ssh again anyway.


Expected results:
ssh should respond something like:
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that the RSA host key has just been changed.
The fingerprint for the RSA key sent by the remote host is
cc:e5:df:24:f6:1a:b4:dd:7d:61:c0:87:bb:98:80:3b.
Please contact your system administrator.

If you know that the key should have changed, delete the offending key by
ssh-keygen -R <hostname>
or by deleting the corresponding line in /root/.ssh/known_hosts.
Offending key in /root/.ssh/known_hosts:9
Then run ssh again to confirm the new key.
RSA host key for scteach.snu.ac.kr has changed and you have requested strict checking.
Host key verification failed.

Additional info: