[pkix] Managing Long-Lived CA certs

"Dr. Pala" <director@openca.org> Mon, 17 July 2017 14:19 UTC

Return-Path: <director@openca.org>
X-Original-To: pkix@ietfa.amsl.com
Delivered-To: pkix@ietfa.amsl.com
Received: from localhost (localhost []) by ietfa.amsl.com (Postfix) with ESMTP id F138413166B for <pkix@ietfa.amsl.com>; Mon, 17 Jul 2017 07:19:48 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -0.343
X-Spam-Status: No, score=-0.343 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, HTML_IMAGE_ONLY_20=1.546, HTML_MESSAGE=0.001, SPF_PASS=-0.001, T_HK_NAME_DR=0.01, URIBL_BLOCKED=0.001] autolearn=no autolearn_force=no
Received: from mail.ietf.org ([]) by localhost (ietfa.amsl.com []) (amavisd-new, port 10024) with ESMTP id 1zntrbVVXgvK for <pkix@ietfa.amsl.com>; Mon, 17 Jul 2017 07:19:47 -0700 (PDT)
Received: from mail.katezarealty.com (mail.katezarealty.com []) by ietfa.amsl.com (Postfix) with ESMTP id 9B27B131BB0 for <pkix@ietf.org>; Mon, 17 Jul 2017 07:19:47 -0700 (PDT)
Received: from dhcp-8e48.meeting.ietf.org (dhcp-8e48.meeting.ietf.org []) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.katezarealty.com (Postfix) with ESMTPSA id DC9B43740F41 for <pkix@ietf.org>; Mon, 17 Jul 2017 10:19:46 -0400 (EDT)
To: pkix@ietf.org
From: "Dr. Pala" <director@openca.org>
Organization: OpenCA Labs
Message-ID: <467c8936-f6aa-0853-878c-24fc8803c599@openca.org>
Date: Mon, 17 Jul 2017 16:19:44 +0200
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:52.0) Gecko/20100101 Thunderbird/52.2.1
MIME-Version: 1.0
Content-Type: multipart/alternative; boundary="------------9AA471A342822CC1C358CC52"
Content-Language: en-US
Archived-At: <https://mailarchive.ietf.org/arch/msg/pkix/qijGaRCyp5z1UQ3W7SIfePingJo>
Subject: [pkix] Managing Long-Lived CA certs
X-BeenThere: pkix@ietf.org
X-Mailman-Version: 2.1.22
Precedence: list
List-Id: PKIX Working Group <pkix.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/pkix>, <mailto:pkix-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/pkix/>
List-Post: <mailto:pkix@ietf.org>
List-Help: <mailto:pkix-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/pkix>, <mailto:pkix-request@ietf.org?subject=subscribe>
X-List-Received-Date: Mon, 17 Jul 2017 14:19:49 -0000


I have a small question for the list regarding long-lived CA 
certificates. Especially in the context of device certificates, we often 
see the use of extra long-lived certificates for Root and Sub CAs (e.g., 
35+ years) combined with limited key sizes (e.g., p256).

Until we have a supported mechanism for reprovisioning devices (...), 
one possible solution for limiting the exposure of the private key would 
be to have a scoped certificate issuance period.

What I am thinking about would be adding an extension that says: "This 
CA can issue certificates from up to 5 years from the validFrom, after 
this, just use it to provide revocation information". This might provide 
some protection in case the CA key is compromised after the initial 5 
years of validity (e.g., certificates issued after that date shall be 

Does such extension exists today ? If not, could this be some work for 


Best Regards,
Massimiliano Pala, Ph.D.
OpenCA Labs Director
OpenCA Logo