Re: [openpgp] AEAD Chunk Size

Bill Frantz <frantz@pwpconsult.com> Fri, 29 March 2019 04:40 UTC

Return-Path: <frantz@pwpconsult.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 C59C61201C3 for <openpgp@ietfa.amsl.com>; Thu, 28 Mar 2019 21:40:07 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.6
X-Spam-Level:
X-Spam-Status: No, score=-2.6 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, URIBL_BLOCKED=0.001] autolearn=ham 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 qzG4wy9NE5lY for <openpgp@ietfa.amsl.com>; Thu, 28 Mar 2019 21:40:05 -0700 (PDT)
Received: from elasmtp-curtail.atl.sa.earthlink.net (elasmtp-curtail.atl.sa.earthlink.net [209.86.89.64]) (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 508F71201A6 for <openpgp@ietf.org>; Thu, 28 Mar 2019 21:40:04 -0700 (PDT)
Received: from [47.143.125.151] (helo=Williams-MacBook-Pro.local) by elasmtp-curtail.atl.sa.earthlink.net with esmtpa (Exim 4) (envelope-from <frantz@pwpconsult.com>) id 1h9jJ5-0001FI-BQ; Fri, 29 Mar 2019 00:39:55 -0400
Date: Thu, 28 Mar 2019 21:39:54 -0700
From: Bill Frantz <frantz@pwpconsult.com>
To: Peter Gutmann <pgut001@cs.auckland.ac.nz>, Bart Butler <bartbutler@protonmail.com>
cc: openpgp@ietf.org, Justus Winter <justuswinter@gmail.com>, "Neal H. Walfield" <neal@walfield.org>, Jon Callas <joncallas@icloud.com>, Jon Callas <joncallas=40icloud.com@dmarc.ietf.org>
X-Priority: 3
In-Reply-To: <1553830376146.79046@cs.auckland.ac.nz>
Message-ID: <r480Ps-10144i-A80E4881F7F14E3ABACDC7ACA10A6056@Williams-MacBook-Pro.local>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: quoted-printable
X-Mailer: Mailsmith 2.4.3 (480)
X-ELNK-Trace: 3a5e54fa03f1b3e21aa676d7e74259b7b3291a7d08dfec79a456044a3aadf2163d0b7f915088aa7a350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c
X-Originating-IP: 47.143.125.151
Archived-At: <https://mailarchive.ietf.org/arch/msg/openpgp/YTLrAfIjjAgWm2HbSMuI_QiJCuU>
Subject: Re: [openpgp] AEAD Chunk Size
X-BeenThere: openpgp@ietf.org
X-Mailman-Version: 2.1.29
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: Fri, 29 Mar 2019 04:40:08 -0000

On 3/29/19 at 8:33 PM, pgut001@cs.auckland.ac.nz (Peter Gutmann) wrote:

>Bill Frantz <frantz@pwpconsult.com> writes:
>
>>The Arduino Uno, which the web site says is the most popular Arduino in the
>>line
>><https://store.arduino.cc/usa/arduino-uno-rev3>, has:
>>
>>Flash Memory 32 KB (ATmega328P) of which 0.5 KB used by bootloader
>>SRAM 2 KB (ATmega328P)
>>EEPROM 1 KB (ATmega328P)
>>
>>So it might be able to use a chunk up to 1KB without having to do the kind of
>>pipelining that leads to security bugs and messy code.
>
>And where does the PGP code and data memory itself fit in all this?
>
>Peter.

Well, we had a version of PGP running on an original IBM PC. 
With careful implementation, you might get the code into 32K 
program memory using the 2K R/W memory for buffers and working 
memory. You also might slip implementing all of the SHOULDs and 
perhaps some of the inappropriate MUSTs. You would probably have 
to also always make the tradeoff for space and not performance.

Remember, the original question was asked by an enbedded system 
developer. How small do they go? If they're looking at Raspberry 
Pi size machines, then they really have it comparatively easy.

Cheers - Bill

------------------------------------------------------------------------
Bill Frantz        |"Insofar as the propositions of mathematics 
refer to
408-356-8506       | reality, they are not certain; and insofar 
they are
www.pwpconsult.com | certain, they do not refer to reality.” 
-- Einstein