Cipher 'none'

[Richard E. Silverman]

For the SSH-2 protocol, I agree with your comments.  I think the "none"
cipher should be available in the standard build, and the client should
print a prominent warning message on connection (and password
authentication should be disabled, of course).  A security concern you
didn't mention is that an attacker might surreptitiously add "cipher none"
to a config file, invisibly rendering connections readable unless someone
uses debug mode and notices the cipher; printing a warning helps alleviate
this concern.

However, for SSH-1, I believe "none" should remain disabled, since without
encryption you effectively lose server authentication and integrity as
well.  This is just too weak to tolerate.  SSH-2 does not suffer from this
problem.

-- 
  Richard Silverman
  slade at shore.net