IETF Logo Mail Archive

Re: [openpgp] Should signatures be rejected if the embedded hash prefix does not match?

Andrew Gallagher <andrewg@andrewg.com> Tue, 28 February 2023 15:17 UTC

Return-Path: <andrewg@andrewg.com>
X-Original-To: openpgp@ietfa.amsl.com
Delivered-To: openpgp@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id E8F1AC14E514 for <openpgp@ietfa.amsl.com>; Tue, 28 Feb 2023 07:17:12 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.097
X-Spam-Level:
X-Spam-Status: No, score=-2.097 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, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_BLOCKED=0.001, RCVD_IN_ZEN_BLOCKED_OPENDNS=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001, URIBL_DBL_BLOCKED_OPENDNS=0.001, URIBL_ZEN_BLOCKED_OPENDNS=0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=andrewg.com
Received: from mail.ietf.org ([50.223.129.194]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id wc69WmU-Qc5P for <openpgp@ietfa.amsl.com>; Tue, 28 Feb 2023 07:17:08 -0800 (PST)
Received: from fum.andrewg.com (fum.andrewg.com [IPv6:2a01:4f9:c011:23ad::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 7E961C14CF0C for <openpgp@ietf.org>; Tue, 28 Feb 2023 07:17:07 -0800 (PST)
Received: from [192.168.1.140] (unknown [176.61.115.103]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (2048 bits) server-digest SHA256) (Client did not present a certificate) by fum.andrewg.com (Postfix) with ESMTPSA id 9555E5F4CF for <openpgp@ietf.org>; Tue, 28 Feb 2023 15:17:02 +0000 (UTC)
DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=andrewg.com; s=andrewg-com; t=1677597422; bh=k+pR8othbUqsQXgjpM00nl2hRb9f+3hSQRcJUpjAYlA=; h=Date:To:References:From:Subject:In-Reply-To:From; b=VKRZUbmoGedUgS2QMs2dBjEHMLjMFi84zfYATYGuYfFxOB+dQ0rBBGGAWHyPAh7RU KYrjjcO6kgGPzizx1CQ21vv8h9wxBK0yjeqJvoQo8ZB4Nd1Aj60ZtXlDEhsW2Ej8Pp /l8BAao4soidsGwtEhOi75Whv0rX7Wm1dxETwkcF7R3wgfEd/il196x9G5lhAzljnt nZLoGLdoYNka1cjTxEnRuJXPPjRKVNPll/wbScfEm9m8Eq4elAvyvFopHW0TwWIi8a AWnvjU3HcvxHarzTpVXz9Wk6P44CEtXvA+1dnZ7coRvPoxzlp1rTq2HULofnmx6uIG fR3ESnoJYPX/A==
Message-ID: <ebd88ec4-787b-fea7-f822-e6b514343dba@andrewg.com>
Date: Tue, 28 Feb 2023 15:17:01 +0000
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.6.1
Content-Language: en-US
To: openpgp@ietf.org
References: <87lekkts65.fsf@fifthhorseman.net> <d759691a-c447-f66d-b839-f1b87e6b89af@andrewg.com> <87y1oj5ltj.fsf@europ.lan> <edeb91b0-6e7e-fa35-c571-d16dff433871@andrewg.com> <87v8jn5e4k.fsf@europ.lan> <55c56429-e1b1-97d3-5ad3-c54a69428143@andrewg.com> <87sfer588g.fsf@europ.lan> <b2a78baa-4636-9353-e079-232d580806a0@andrewg.com> <87o7pe69m6.fsf@europ.lan> <6lLcuziqTC31StjVfWBQYzemBHmXkVQG_LV6cIQ1lQU7qtOTr-HKCRHzxSY5LXsFU_BnnElSN0zry-RGK8TtC5cM_Ab4KsuWSPON8-82ZOM=@protonmail.com>
From: Andrew Gallagher <andrewg@andrewg.com>
In-Reply-To: <6lLcuziqTC31StjVfWBQYzemBHmXkVQG_LV6cIQ1lQU7qtOTr-HKCRHzxSY5LXsFU_BnnElSN0zry-RGK8TtC5cM_Ab4KsuWSPON8-82ZOM=@protonmail.com>
Content-Type: text/plain; charset="UTF-8"; format="flowed"
Content-Transfer-Encoding: 7bit
Archived-At: <https://mailarchive.ietf.org/arch/msg/openpgp/On7rLI_za6k76tD8QkHTDCeREps>
Subject: Re: [openpgp] Should signatures be rejected if the embedded hash prefix does not match?
X-BeenThere: openpgp@ietf.org
X-Mailman-Version: 2.1.39
Precedence: list
List-Id: "Ongoing discussion of OpenPGP issues." <openpgp.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/openpgp>, <mailto:openpgp-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/openpgp/>
List-Post: <mailto:openpgp@ietf.org>
List-Help: <mailto:openpgp-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/openpgp>, <mailto:openpgp-request@ietf.org?subject=subscribe>
X-List-Received-Date: Tue, 28 Feb 2023 15:17:13 -0000

On 28/02/2023 10:50, Daniel Huigens wrote:
> If broken signatures are
> widespread, I would be OK with removing the check for v4 signatures,
> and checking it only for v6 sigs; or we could add a config option.

How about the following?

```
An implementation MAY accept v3 or v4 signatures where these octets 
don't match the computed hash but the signature is otherwise valid. It 
MUST NOT modify such malformed signatures.
```

This is more or less a statement of current reality, with an added 
prohibition against invalidating any checksum over the signature packet. 
Any implementation that wishes to be more strict can do so.

A

v2.23.0 | Report a Bug | By Email