Re: [pkix] Private key usage period extension

Peter Rybár <peter.rybar@nbusr.sk> Fri, 06 May 2016 09:51 UTC

Return-Path: <prvs=09344e319b=peter.rybar@nbusr.sk>
X-Original-To: pkix@ietfa.amsl.com
Delivered-To: pkix@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 93EBD12D1C7 for <pkix@ietfa.amsl.com>; Fri, 6 May 2016 02:51:11 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -0.051
X-Spam-Level:
X-Spam-Status: No, score=-0.051 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DOS_OUTLOOK_TO_MX=2.845, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_NONE=-0.0001, RP_MATCHES_RCVD=-0.996, SPF_PASS=-0.001] autolearn=no autolearn_force=no
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id njFvj9PVLsc9 for <pkix@ietfa.amsl.com>; Fri, 6 May 2016 02:51:09 -0700 (PDT)
Received: from mail.nbusr.sk (mail.nbusr.sk [84.245.65.227]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 9CB8612B057 for <pkix@ietf.org>; Fri, 6 May 2016 02:51:08 -0700 (PDT)
From: =?iso-8859-2?Q?Peter_Ryb=E1r?= <peter.rybar@nbusr.sk>
To: "'Erik Andersen'" <era@x500.eu>, "'Directory list'" <x500standard@freelists.org>, "'PKIX'" <pkix@ietf.org>
References: <000901d1a773$379e1680$a6da4380$@x500.eu>
In-Reply-To: <000901d1a773$379e1680$a6da4380$@x500.eu>
Date: Fri, 6 May 2016 11:50:53 +0200
Message-ID: <201605060951.u469p536017433@mail.nbusr.sk>
MIME-Version: 1.0
Content-Type: multipart/alternative; boundary="----=_NextPart_000_0025_01D1A78D.8B0F5440"
X-Mailer: Microsoft Outlook 14.0
Thread-Index: AQJYEc9fvtVi9SNiQE1fwP6vqYjwqJ6e0hvA
Content-Language: sk
X-NAI-Spam-Flag: NO
X-NAI-Spam-Level:
X-NAI-Spam-Threshold: 6
X-NAI-Spam-Score: 0.4
X-NAI-Spam-Version: 2.3.0.9418 : core <5663> : inlines <4769> : streams <1630866> : uri <2204260>
Archived-At: <http://mailarchive.ietf.org/arch/msg/pkix/fmHru4f7uIt3ID1LX4T1RVeCe3k>
Subject: Re: [pkix] Private key usage period extension
X-BeenThere: pkix@ietf.org
X-Mailman-Version: 2.1.17
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: Fri, 06 May 2016 09:51:11 -0000

One key pair can be included in many certificates e.g. cross-certificates.

The validity period of each cross-certificate can be different.

After the time value of notAfter field of the Private key usage period
extension of  the Private key used for signing,  any duplication of the
private key are deleted.

 

Peter

 

From: pkix [mailto:pkix-bounces@ietf.org] On Behalf Of Erik Andersen
Sent: Friday, May 6, 2016 10:42 AM
To: Directory list; PKIX
Subject: [pkix] Private key usage period extension

 

X.509 has a specification of the Private key usage period extension
(8.2.2.5). This extension is a little confusing. It has notBefore and
notAfter specification. However, the text says:

 

The notBefore component indicates the earliest date and time at which the
private key could be used for signing. If the notBefore component is not
present, then no information is provided as to when the period of valid use
of the private key commences. The notAfter component indicates the latest
date and time at which the private key could be used for signing. If the
notAfter component is not present then no information is provided as to when
the period of valid use of the private key concludes.

 

With a little ill will, this can be read as the private key validation
period may extend beyond the validity of the public key. Note 1 adds to the
confusing, as it says:

 

NOTE 1 - The period of valid use of the private key may be different from
the certified validity of the public key as indicated by the certificate
validity period. With digital signature keys, the usage period for the
signing private key is typically shorter than that for the verifying public
key.

 

It is the word "typical" that confuses me. It implies it could be different.

 

This extension was included in RFC 3280 with a heavy health warning. It was
omitted from RFC 5280 (except for A.2).

 

In my mind, the validity of the private key should not spread outside the
validity period of the certificate.

 

Have I misunderstood something?

 

Erik