Re: suggestion for new ssh maintenance wg

denis bider <ietf-ssh3%denisbider.com@localhost> , 1/29/2016 9:59 PM:

With regard to AEAD:

I think we should just make the following simple and clear statement:

MAC algorithms are secondary to encryption algorithms, and are evaluated only if the encryption algorithm is not AEAD. If an AEAD encryption algorithm is negotiated, the outcome of MAC negotiation is irrelevant and must be ignored. If no mutual MAC algorithms are available, this causes key exchange to fail if, and only if, the negotiated encryption algorithm is not AEAD.

I believe this is what aesXXX-gcm%openssh.com@localhost does, and is the behavior that makes most sense to me.

With regard to SFTP:

We may not have an agreement in what SFTP should be; but by necessity, we have an agreement in what it is.

I suggest we should simply do the minimum work possible to promote the following drafts to some type of RFC, and call it a day:

SFTP v3 - as implemented by OpenSSH and everyone who wants to interoperate with it
https://tools.ietf.org/html/draft-ietf-secsh-filexfer-04

SFTP v6 - implemented by many (perhaps most?) clients and servers
https://tools.ietf.org/html/draft-ietf-secsh-filexfer-13
https://tools.ietf.org/html/draft-galb-filexfer-extensions-00

This is the de facto SFTP as we have it. Implementers have to follow these drafts, so they might as well be RFCs.

----- Original Message -----

From: Niels "Möller"

Sent: Friday, January 29, 2016 15:34

To: Stephen Farrell

Cc: ietf-ssh%NetBSD.org@localhost ; denis bider ; Watson Ladd ; Daniel Migault ; Curdle Chairs ; mdb%juniper.net@localhost

Subject: Re: suggestion for new ssh maintenance wg

Stephen Farrell <stephen.farrell%cs.tcd.ie@localhost> writes:

> If you think such an ssh maintenance wg is a bad plan,

> please also do say that and why you think that.

There's definitely some work that needs to be done. I'm not very

familiar with ietf processes, so I'm not sure a new working group would

make it easier to make progress. I guess what's needed is either an

active wg chair, or an active area director, or someone informally

accepting (and being accepted) in a similar role.

> PPS: Note that this could be short-lived wg that never

> needs to meet face-to-face, or maybe it'd not be like that,

> but don't get fussed about having to go to IETF meetings

> to get this work done - if it's maintenance then that may

> well not be needed.

Don't worry about IETF meetings. I felt I was deeply involved during the

work on the ssh rfc:s. And I've never been to a secsh wg meeting, only

on the mailing list. (I've actually been to one ietf meeting in my life,

but the secsh wg didn't meet that time).

>> Extension negotiation for SSH:

>> https://datatracker.ietf.org/doc/draft-ssh-ext-info

An extension mechanism makes sense to me, but I find most of the

proposed extensions questionable and/or hard to get right.

>> In addition to the above, I very much agree that aes-gcm%openssh.com@localhost

>> needs standardization.

I think the single issue that might motivate forming a new wg is how to

properly negotiate the use of aead crypt in ssh. There should be no

difference between aes-gcm (which I'm not very fond of) and

chacha-poly1305.

>> Among other things, the erstwhile SSH working group never finalized

>> the SFTP spec due to lack of consensus. We now have two SFTP specs,

>> version 3 implemented by OpenSSH, and version 6 implemented by most

>> everyone else.

I honestly doubt we'll see much progress there, wg or not. It was a bit

too much of second system syndrome. But if some others have the energy

to revive it, I can't object, of course.

Regards,

/Niels

--

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