[EXT] Re: enabling "none" cipher

[Darren Tucker]

On Tue, 13 Jan 2026 at 08:08, Blumenthal, Uri - 0553 - MITLL <uri at ll.mit.edu>
wrote:
> Isn't “none” cipher still authenticated, for both login and traffic?

The cipher itself is not, but there is a separate Message Authentication
Code (MAC) on each SSH packet.  The spec also allows the MAC to be "none"
but OpenSSH doesn't and offhand I don't know of an implementation that does.

> Don’t some organization care for authenticity, though not (that much) for
confidentiality

Without SSH encryption, the passwords in password based logins (including
keyboard-interactive) are also in plain text.  This is probably why even
the HPN folks don't start with none, but instead start with a cipher then
later rekey to "none".

 --
Darren Tucker (dtucker at dtucker.net)
GPG key 11EAA6FA / A86E 3E07 5B19 5880 E860  37F4 9357 ECEF 11EA A6FA
    Good judgement comes with experience. Unfortunately, the experience
usually comes from bad judgement.