Re: [openpgp] AEAD Chunk Size

"Neal H. Walfield" <neal@walfield.org> Mon, 18 March 2019 08:51 UTC

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Date: Mon, 18 Mar 2019 09:51:47 +0100
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From: "Neal H. Walfield" <neal@walfield.org>
To: Tobias Mueller <muelli@cryptobitch.de>
Cc: Sebastian Schinzel <schinzel@fh-muenster.de>, openpgp@ietf.org
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Subject: Re: [openpgp] AEAD Chunk Size
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On Sun, 17 Mar 2019 20:35:19 +0100,
Tobias Mueller wrote:
> > The advantage of smaller
> > chunks is that the plaintext can be cached until the chunk's auth tag
> > is validated. That's to guarantee that no unauthenticated plaintext is
> > released. (Leaving truncation aside.)
> 
> Two things: Firstly, you write "can be cached" rather than "must be
> cached".

I think Sebastian is using "can" to mean "it is possible", not "may".

That is, 

  The advantage of smaller
  chunks is that *it is possible* to cache the plaintext until the chunk's auth tag
  is validated *whereas it is not necessarily possible to cache the
  plaintext with larger chunks*.

Neal