Re: [openpgp] Request on Adding ChaCha20-Poly1305 to the OpenPGP Standardization

Peter Gutmann <pgut001@cs.auckland.ac.nz> Thu, 16 April 2020 01:47 UTC

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From: Peter Gutmann <pgut001@cs.auckland.ac.nz>
To: Tanveer.Salim <Tanveer.Salim@protonmail.com>, Bart Butler <bartbutler@protonmail.com>
CC: "openpgp@ietf.org" <openpgp@ietf.org>
Thread-Topic: [openpgp] Request on Adding ChaCha20-Poly1305 to the OpenPGP Standardization
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Date: Thu, 16 Apr 2020 01:46:50 +0000
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Subject: Re: [openpgp] Request on Adding ChaCha20-Poly1305 to the OpenPGP Standardization
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Bart Butler <bartbutler=40protonmail.com@dmarc.ietf.org> writes:

>It does not seem worth it to me, at least at this time.

Another problem with ChaCha20-Poly1305 is that it's incredibly brittle unless
you get the keying details exactly 100% right.  There's at least two full-
blown lengthy RFCs written that cover nothing but the complex keying
requirements, and if you get them wrong you get a catastrophic failure of
security.  For things like TLS it may not be that bad because an attacker
would have to intercept and analyse live data at a particular point in time,
while for OpenPGP they could go back years later to stored data to take
advantage of a flaw.  It's like using nitroglycerine vs. TNT, they both have
the same end effect if you get everything just right, but I'd never even
consider the former.

Peter.