Where do I put my legacy key on iPad OS 15? I get:
No private keys found in “/var/mobile/Containers/Data/Application/(a uuid went here)/Documents”.
And also, if I am chatting with someone who is using my old, legacy key, will that chat continue to use that old key? That’s what I’d want; while most peeps are on the new (Delta Chat, from my old Android installation) key, some are on the old key (gpg, from my desktop/Emacs).
Where do I put my legacy key on iPad OS 15?
it should be the same place as described at Import backup to iOS
the last imported key overwrites the existing “primary” key and will be used for Autocrypt encrypting/signing. old keys will still be used for decryption, however.
to import legacy keys that should not become the primary key, you have to add the word legacy somewhere to the filename. in this case the key is only used for decryption.
And also, if I am chatting with someone who is using my old, legacy key, will that chat continue to use that old key?
old key will be used for decryption only, there is no way to encrypt to different primary keys for different users.
there is only one primary key at any point, that key is used for Autocrypt encrypting/signing on outgoing messages.
I will name if legacy.pgp 
Maybe it’s smarter for me to go back to my old key; the new (DeltaChat generated) key has been used for like a hundred more emails, but to only two people and they’ve both been on autocrypt so could probably deal with me going back to the old (pre-autocrypt) key. (Because that’s what will happen, right? If I don’t put “legacy” my old crusty gpg key become the new key and the Delta Chat–generated key will be “legacy”, but the chats will still work with everyone?)
Regardless, I’ve been trying to place the key using the Files app on Delta Chat in its folder on there and that hasn’t worked, giving me (in the console log) the error message in this thread’s OP. I’ll try to connect via the finder at the home of a mac-using friend as per that backup thread.
OK, so, I was placing it in the right folder all along (“On my iPad → Delta Chat”) but it needs to be in the .asc format, not the .pgp format.
I now use my old classic been using it for many years key! The header is almost four times longer but, it works!
So this is the situation right now!
Old key I’ll refer to as “gpg key” now imported as new primary in Delta Chat. So it’s both old and new.
In between, I was using a “Delta Chat generated key” (that started on Android but was exported to iOS).
In Emacs, I can read the new Delta Chat messages that I’ve sent since I imported the “gpg key”, and I can’t read the ones that were sent during the era when I was using the “Delta Chat generated key”. So far so awesome
In Delta Chat, I still can’t read messages that were sent to the “gpg key” that Delta received during the “Delta Chat generated key” era. I wanna, uh, “reload” them somehow so Delta Chat can grok them.
Also I wonder if someone sends me a gpg-encrypted message (manually encrypted, not using autocrypt) to my “gpg key”, as people are wont to do, and I reply from Delta, will my response be sent encrypted? It’s always awesome seeing the li’l “padlock” but sometimes I don’t even wanna hit send for fear of it being sent in plaintext. ← this is ultimately a question about what “mutual” means in the context of autocrypt: both people using GPG, or both people using autocrypt specifically?
Since I can padlock-chat with people on K9’s autocrypt just fine.