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Re: [openpgp] AEAD Chunk Size

Peter Gutmann <pgut001@cs.auckland.ac.nz> Fri, 29 March 2019 12:53 UTC

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From: Peter Gutmann <pgut001@cs.auckland.ac.nz>
To: "Neal H. Walfield" <neal@walfield.org>
CC: Jon Callas <joncallas=40icloud.com@dmarc.ietf.org>, "openpgp@ietf.org" <openpgp@ietf.org>, Justus Winter <justuswinter@gmail.com>, Jon Callas <joncallas@icloud.com>
Thread-Topic: [openpgp] AEAD Chunk Size
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Date: Fri, 29 Mar 2019 12:53:42 +0000
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Subject: Re: [openpgp] AEAD Chunk Size
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Neal H. Walfield <neal@walfield.org> writes:

>I'm having trouble imagining why a larger chunk size would ever be better in
>either of these cases.
>
>  - File encryption: smaller chunk size means finding errors faster

See my followup messages, for data at rest you probably don't care about
errors at all, and if you really do then having the report at the whole-file
level is fine.  What's the benefit gained from knowing that the 64kB block at
offset xyz is corrupt?

As I mentioned earlier, we really need some data on real-world use cases
rather than hypothesising problematic corner cases that will rarely, if ever,
occur.

Peter.

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