Re: [openpgp] Backwards compatibility

Sebastian Schinzel <schinzel@fh-muenster.de> Wed, 25 October 2023 17:34 UTC

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From: Sebastian Schinzel <schinzel@fh-muenster.de>
To: Paul Schaub <vanitasvitae@riseup.net>
CC: "openpgp@ietf.org" <openpgp@ietf.org>
Thread-Topic: [openpgp] Backwards compatibility
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Date: Wed, 25 Oct 2023 17:33:59 +0000
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References: <CBAF59DC-8F4E-4E1B-979B-6838D4F662E0@nohats.ca> <87jzrjx3jc.fsf@jacob.g10code.de> <774b9eea-1d06-c957-dc21-4457989c896d@nohats.ca> <87r0lrulsw.fsf@jacob.g10code.de> <87lebrvst1.fsf@europ.lan> <8734xy1yul.fsf@jacob.g10code.de> <5875B387-E444-4724-B9CC-12E659A311B8@riseup.net>
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Subject: Re: [openpgp] Backwards compatibility
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> Am 25.10.2023 um 18:34 schrieb Paul Schaub <vanitasvitae@riseup.net>:
> 
> A downgrade attack is a downgrade attack. As the sender, you can't know and can't control which software, and what policies the recipient uses, so you can't argue "ah, your client should have rejected this message“.

It’s also unclear what to do with ciphertexts that are encrypted with old packet types.

Back in 2018 when Enigmail had to fix gnupg’s strange way of warning of type 9 packets, Enigmail users weren’t happy at all. 

See this thread:
https://sourceforge.net/p/enigmail/forum/support/thread/03ebee57/