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[openpgp] Re: Encryption subkey selection

Falko Strenzke <falko.strenzke@mtg.de> Tue, 08 April 2025 05:31 UTC

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Date: Tue, 08 Apr 2025 07:31:28 +0200
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To: Andrew Gallagher <andrewg=40andrewg.com@dmarc.ietf.org>
References: <26f46aef-dde6-4564-92b2-2914aa574944@mtg.de> <E84CD5EE-DAAF-44D6-BCEE-CB92AE6CBBEC@andrewg.com> <-r7DKP-up_y2Y19C3aR7UREiHK6ddwWmMF9wJ55R52gaDYWBiRBQYI5rMI6HXFbuWqZC9ykPncT3fj9Mu48g6S6P4wahJDwziqDkFZ0i5cc=@pm.me> <b1748002-189a-40c0-8221-50f475749c79@mtg.de> <178660AC-CC71-4CCE-98EA-6456677A31D9@andrewg.com>
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From: Falko Strenzke <falko.strenzke@mtg.de>
Organization: MTG AG
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Subject: [openpgp] Re: Encryption subkey selection
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I think that is an absolutely logical progression. Still I am not sure 
how strongly the two mechanisms should be linked by their 
specifications. Even if this progression wasn't part of the normative 
spec, it could be mentioned as the recommended behaviour. But in any 
case, I am prepared to be convinced also of strongly linking the 
mechanisms if that should bring considerable advantage. Nevertheless, in 
the field there may always be implementations that support only one but 
not the other – or even neither –, so the certificate holder must be 
prepared that about anything can happen in terms of what set of 
encryption subkeys of his certificates will be used.

Best regards,
Falko

Am 07.04.25 um 19:11 schrieb Andrew Gallagher:
> On 7 Apr 2025, at 11:13, Falko Strenzke <falko.strenzke@mtg.de> wrote:
>>
>> In case of b) it doesn't seem to matter that much if we assign 
>> implicit rank 0 to keys or keep them outside the ESS selection 
>> algorithm altogether. I would tend to say in case the ESS selection 
>> fails, the sender should be be able to pick any set of encryption 
>> subkeys – whether they have an associated ESS or not.
>>
> In the case where a fallback cert exists, and no usable set of ranked 
> subkeys can be found on the preferred cert, should a receiving 
> implementation try the fallback cert's subkeys before or after 
> reverting to “any reasonable method” on the preferred cert?
>
> A
>
>
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-- 

*MTG AG*
Dr. Falko Strenzke

Phone: +49 6151 8000 24
E-Mail: falko.strenzke@mtg.de
Web: mtg.de <https://www.mtg.de>

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