def check_auth_publickey(self, username, key):
return AUTH_FAILED<EOL>
Determine if a given key supplied by the client is acceptable for use
in authentication.  You should override this method in server mode to
check the username and key and decide if you would accept a signature
made using this key.

Return L{AUTH_FAILED} if the key is not accepted,
L{AUTH_SUCCESSFUL} if the key is accepted and completes the
authentication, or L{AUTH_PARTIALLY_SUCCESSFUL} if your
authentication is stateful, and this password is accepted for
authentication, but more authentication is required.  (In this latter
case, L{get_allowed_auths} will be called to report to the client what
options it has for continuing the authentication.)

Note that you don't have to actually verify any key signtature here.
If you're willing to accept the key, ssh will do the work of
verifying the client's signature.

The default implementation always returns L{AUTH_FAILED}.

@param username: the username of the authenticating client
@type username: str
@param key: the key object provided by the client
@type key: L{PKey <pkey.PKey>}
@return: L{AUTH_FAILED} if the client can't authenticate
    with this key; L{AUTH_SUCCESSFUL} if it can;
    L{AUTH_PARTIALLY_SUCCESSFUL} if it can authenticate with
    this key but must continue with authentication
@rtype: int