Re: [openpgp] AEAD Chunk Size

"Derek Atkins" <derek@ihtfp.com> Fri, 12 April 2019 14:10 UTC

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Date: Fri, 12 Apr 2019 10:10:21 -0400
From: "Derek Atkins" <derek@ihtfp.com>
To: "Neal H. Walfield" <neal@walfield.org>
Cc: "Marcus Brinkmann" <marcus.brinkmann=40ruhr-uni-bochum.de@dmarc.ietf.org>, openpgp@ietf.org
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Subject: Re: [openpgp] AEAD Chunk Size
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Hi,

On Fri, April 12, 2019 9:46 am, Neal H. Walfield wrote:
> On Fri, 12 Apr 2019 15:36:58 +0200,
> Derek Atkins wrote:
>> Marcus Brinkmann <marcus.brinkmann=40ruhr-uni-bochum.de@dmarc.ietf.org>
>> writes:
>>
[snip]
>> In my mind, this sounds like the implementation is broken.  If it
>> releases AEAD plaintext before the end of the AEAD chunk then it is
>> non-conforming and should be considered broken.
>
> I fully agree with you.
>
> Given this position, it seems to me that all implementations will
> necessarily fail on very large chunks (e.g., 4 exabytes).  So, why
> even allow them [1]?  It seems to me that these permissible options
> just create a temptation to create broken implementations.

Not necessarily; it could buffer to disk (just like PGP2 did, and even
PGP3/5 in certain circumstances).  In my mind, buffering to disk is not
the same as releasing the plaintext.  So it COULD still be conformant,
even with 4 exabytes.

> Thanks,

-derek


-- 
       Derek Atkins                 617-623-3745
       derek@ihtfp.com             www.ihtfp.com
       Computer and Internet Security Consultant