Re: [openpgp] Intended Recipient observation

"Neal H. Walfield" <neal@walfield.org> Fri, 16 April 2021 16:42 UTC

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Date: Fri, 16 Apr 2021 18:41:58 +0200
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From: "Neal H. Walfield" <neal@walfield.org>
To: vedaal@nym.hush.com
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Subject: Re: [openpgp] Intended Recipient observation
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On Fri, 16 Apr 2021 18:31:01 +0200,
vedaal@nym.hush.com wrote:
> On 4/16/2021 at 10:24 AM, "Neal H. Walfield" <neal@walfield.org> wrote:
>  Why would Alice want to import M's key?

In the software that I'm working on the "keyring" is simply a cache.
We aggresively harvest all keys that we encounter (storage is cheap),
and rely on our trust model to separate the wheat from the chaff.

>  Still, in order for her to Import M' as a new key by M, she would check first if M' was also signed by M.
>  If she then sees a decryption problem, she would (thanks to your pointing this out), 
>  check for duplicate subkey S in her keyring, and then find out that M does bear her ill will.

In my opinion, we should shift as little complexity as possible to the
user.  In our case, this means that Sequoia has to worry about a lot
more corner cases, such as this one, but I think it is worth it.

>  As most users are familiar with their encryption subkey's
>  fingerprint, it would be a good idea to check any prospective
>  public key for an encryption subkey fingerprint, before importing
>  it.

The user population that I'm targetting doesn't understand how to do
this nor do they want to learn about these nuances.

>  Thanks for pointing this out.
>  (Doesn't affect me though, as am from old school that doesn't use subkeys,
>  where the primary certificate signs, decrypts and authenticates).

Thanks for the feedback!

:) Neal