Re: What ASN.1 got right

Nico Williams <> Wed, 03 March 2021 00:51 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id EDF693A1573 for <>; Tue, 2 Mar 2021 16:51:45 -0800 (PST)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -2.1
X-Spam-Status: No, score=-2.1 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (1024-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id ST8y6288ivrs for <>; Tue, 2 Mar 2021 16:51:44 -0800 (PST)
Received: from ( []) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 1CFE83A1572 for <>; Tue, 2 Mar 2021 16:51:44 -0800 (PST)
X-Sender-Id: dreamhost|x-authsender|
Received: from (localhost []) by (Postfix) with ESMTP id EE98932248E; Wed, 3 Mar 2021 00:51:42 +0000 (UTC)
Received: from (100-98-118-122.trex.outbound.svc.cluster.local []) (Authenticated sender: dreamhost) by (Postfix) with ESMTPA id 7DB60322286; Wed, 3 Mar 2021 00:51:42 +0000 (UTC)
X-Sender-Id: dreamhost|x-authsender|
Received: from ( []) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384) by (trex/6.0.2); Wed, 03 Mar 2021 00:51:42 +0000
X-MC-Relay: Good
X-MailChannels-SenderId: dreamhost|x-authsender|
X-MailChannels-Auth-Id: dreamhost
X-Chief-Troubled: 443a3cc92c4d9867_1614732702829_2004766899
X-MC-Loop-Signature: 1614732702829:2996080146
X-MC-Ingress-Time: 1614732702829
Received: from (localhost []) by (Postfix) with ESMTP id 409D47E6D9; Tue, 2 Mar 2021 16:51:41 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha1; c=relaxed;; h=date :from:to:cc:subject:message-id:references:mime-version :content-type:in-reply-to;; bh=xRzdud1QYWEci3 AhNmDZ/sdKYpU=; b=WDZ9P/uiCEqaj0rcLjefBH1xIXLlNqTsLzViYaRch9ZlpE u9DqA/cz1F9y8Zmu0dEW1SYDjLEV535oJ3yeapxcKAEVV0EsmRrna2Mhtcoq7ceW +usLsWSjKzEPewqzPIydFVSCm2Mo0qfyECmd7R11XpCc5FjRDtHz+0WPzS22w=
Received: from localhost (unknown []) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: by (Postfix) with ESMTPSA id 310937E3D5; Tue, 2 Mar 2021 16:51:38 -0800 (PST)
Date: Tue, 2 Mar 2021 18:51:36 -0600
X-DH-BACKEND: pdx1-sub0-mail-a14
From: Nico Williams <>
To: Michael Thomas <>
Cc: Phillip Hallam-Baker <>, IETF Discussion Mailing List <>
Subject: Re: What ASN.1 got right
Message-ID: <20210303005136.GB30153@localhost>
References: <> <> <> <> <> <> <20210302234928.GX30153@localhost> <> <20210303002330.GZ30153@localhost> <>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <>
User-Agent: Mutt/1.9.4 (2018-02-28)
Archived-At: <>
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: IETF-Discussion <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Wed, 03 Mar 2021 00:51:46 -0000

On Tue, Mar 02, 2021 at 04:43:10PM -0800, Michael Thomas wrote:
> On 3/2/21 4:23 PM, Nico Williams wrote:
> > I wouldn't want to do this.  It's much more complex than the client
> > sending a certificate.
> Huh? It's a bit of configuration on the server side that is probably
> captured in provisioning systems. And client provisioning -- which is what
> certs imply -- is extremely problematic. How do I get a client ssh cert onto
> my phone's ssh app, for example? Not having to change client behavior or
> provisioning significantly simplifies the problem.

It's the same problem as getting the keys into the directory.

> Not having to do anything at all on the client is a significant savings. I
> would much rather the help desk cost of nothing different than taking calls
> on how to install the ssh certs on exotic and not so exotic clients.

Yes, if you ignore the part about having to get the keys into the

> > > If you care about that, I suppose. I think most people do the leap of faith
> > > and known_hosts ignores the problem.
> > I very much care about that.  Certainly in a corporate network.
> It's orthogonal to the client side authentication problem though.

It's a similar problem, and you can't ignore it.

> Uploading a new public keys is the ~same for both. Downloading a client cert
> is a whole lot of something. And if your corpro directory is down, you are
> already in a world of hurt. The advantage of offline verification in the age
> of 24/7 internet is very niche.

We have an online CA with an HTTP API.  You POST a CSR authenticating
with whatever credentials you've got, and you get back a short-live
certificate for your authenticated name(s) or for the requested name(s)
if you're authorized to them.  Using this is trivial.