Even though this likely will not help your case - I think I tracked the
cause of my problem to a sufficient extent, as follows:
For the recipient in question, the e-mail address stored in my Android
contact DB ("[email protected]") had a case difference w.r.t. the e-mail
listed in the OpenPGP key DB ("[email protected]").
Now formally, mailbox identifiers are indeed considered case-sensitive (see
[1] for some RFC-level analysis). Therefore, the K-9 Mail/OpenKeychain
combo was technically right to tell me that no key was known for
"john.doe".
On the other hand, lots of organizations have their mail servers configured
to ignore such case differences, with the effect that people are quite used
to having them ignored.
Like e.g. my contact who, based on this assumtion, decided to capitalize
his name in the e-mail address he attached to his PGP key - even though he
had used and circulated only the all-lowercase variant of his e-mail
address earlier.
Or like me, so that it took me quite some time to realize what the heck
went wrong.
Anyway, the problem vanished after I modified the address in the contacts
DB - to the capitalized version, which isn't correct but in my specific
case luckily works.
This is not a general solution, but was my only option as the key DB
entries cannot be modified.
In conclusion, I think the best way for K-9 Mail/OpenKeychain to treat this
situation would be to first try the current (case-sensitive) mode of
retrieval, and if that fails, attempt a case-insensitive retrieval,
If only the latter one succeeds, a warning could appear, so the user has a
chance to think twice wether case-equivalence is indeed intended here.
[1]
https://social.technet.microsoft.com/Forums/exchange/en-US/69f393aa-d555-4f8f-bb16-c636a129fc25/what-are-valid-and-invalid-email-address-characters?forum=exchangesvradminlegacy
Am Sonntag, 5. Februar 2017 16:35:56 UTC+1 schrieb [email protected]:
>
> hi, i have the very same issues since k9mail 5.203 update. is that a bug
> or a feature ;-)
>
> Am Donnerstag, 19. Januar 2017 17:19:02 UTC+1 schrieb TE:
>>
>> No ideas folks? To expand on my problem description:
>>
>> Following a hint in a thread on the K-9 Mail Developers List, I made
>> sure that the recipient in question is in my Android contacts DB (earlier
>> it had not been present there).
>> However, I'm still not able to send this contact a PGP-encrypted mail.
>>
>> So now my siutuation is:
>> - using current PlayStore versions of K-9 Mail and OpenKeychain
>> - recipient's public key are in OpenKeychain's key DB
>> - For my own key is present in OpenKeychain's key DB as well (albeit
>> stripped,
>> since I'm using an NFC OpenPGP card)
>> - recipients e-mail (the one shown as associated to his public PGP key in
>> OpenKeychain)
>> is in Contacts DB
>> - OpenKeychain is registered in K-9 account settings
>> - K-9 has permission to access OpenKeychain
>>
>> Nevertheless, no recipient key is found when I try to send a newly
>> composed mail to the receiver with encryption selected.
>> Which necessary condition for sending encrypted mail did I miss?
>>
>> Best regards
>>
>>
>> Am Donnerstag, 12. Januar 2017 12:15:02 UTC+1 schrieb TE:
>>>
>>> Hello,
>>>
>>>
>>> Using current versions of K-9 and OpenKeychain from Play Store, i can
>>> receive and decrypt encrypted mails fine. Really impressive work,
>>>
>>> However sending encrypted mails does currently not work for me. K-9 does
>>> not find any keys for the recippient.
>>> I confirmed that
>>> - the recipient's key is present in OpenKeychain's key DB
>>> - it is marked as trusted there
>>> - and his identity shows exactly the same e-mail address I am using when
>>> attempting to send an encrypted e-mail
>>> Any ideas on how to fix this, or even just how to debug what's going on?
>>> I already revoked and re-instantiated K9's access to openkeychain, as
>>> per some earlier suggetsion from this list, but to no avail.
>>>
>>>
>>>
>>
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