Why encryption not working anymore - howto force encryption


I use DC since v0.5 from f-droid. Thanks for your good work.
Over time I had a strange problem with only a few, not with all chat partners.
Everthing works and suddenly “the encryption did not work anymore” or “message are not received at all”.

I think in case of “message are not received at all” this could be related to different versions, e.g. one chat partner used DC from google market and had newer version compared to version from f-droid.
Can somebody enlighten this situation out of his/her experience?

The second issue “the encryption did not work anymore” is more important - I’m still clueless and I’m not able to solve it.

So my main question would be: how to enable encryption again???

some more details:
chat partner use gmail.
last message succesfully encrypted is from beginning this year.
we did not have contact for a couple of month. if I write chat partner or vice versa, all messages are plaintext.
I updated to 1.12.0 and used the desktop client (the same with APK). Chat partner told me they always use latest version.
I removed and added the contact again. no difference.

Anybody has a explanation or clue?

  1. Try updating manually to the latest version, currently it is https://download.delta.chat/android/deltachat-gplay-release-1.12.3.apk. If you are using F-Droid, update through F-Droid or by downloading https://f-droid.org/repo/com.b44t.messenger_592.apk There were fixes for reading key fingerprints from the database recently.
  2. Make sure Advanced setting “Prefer end-to-end encryption” is enabled on both sides. You can select “Encryption” menu item in the contact screen (click the avatar). If it says “End-to-end encryption available” instead of “End-to-end encryption preferred”, it means you contact has not enabled this setting.
  3. Send one message in each direction to update the settings.
  4. Send a message and open the log immediately after that. Look for messages about “peerstate”.

hi link2xt, thanks for your fast reply.

I’m looking into this for long time. And I’m not the type who write any question in some forum. I haven’t found any clues in this forum or other places and I wonder how others deal with such situation.

1.) I have latest 1.12.2 from f-droid and 1.12.0 desktop(win) and did not do that step yet, but in the past along with a lot of other things. I think I need to backup DC and re-install for this step. Android can’t give me hints about updates and I doubt it would help. It’s not the first time this happens to me. In all other cases the other chat partner changed the mail to another and it did work again; anything else didn’t work. It’s the third time with different chat partners this happens suddenly. And with the latest case my chat partner does not want to change the mail and is hardly willing to help (w.g. write another message back).

2.) thanks for the hint. I checked and it says “End-to-end encryption available” on my side. I did never change “Prefer end-to-end encryption” setting myself, can’t tell about the chat partner, but I highly doubt it.

3.) I do this since 18th of august, and I have no physical contact to chat partner.

4.) sounds good. searching how to open the DC log show me a lot of entries regarding ‘blog’. Can somebody provide a link how to do so?

Are there more ideas how to fix it easily?
deleting the contact and create a same new entry in DC (did not work, it’s not really removing as far as I can tell).
forcing the initial key exchange, like the first time I exchange a message with somebody new.

BTW: And I noticed a small bug with your DC desktop installer.
It hangs indefinitely, because
I renamed the install folder before manually, and as a result the DC setup couldn’t find/execute the uninstaller.
Should I create a thread for this in this forum?

hi link2xt,

I have found the log on my disc (DC desktop for Win).
I think you mentioned this lines:
great forum, I can’t post the log entries (three lines), reason: “Sorry, new users can only put 2 links in a post.”
first line:
2020-08-26T00:02:31.698Z core/event INFO “DC_EVENT_INFO” 0 “src\chat.rs:858: [autocrypt] peerstate for XXXXXXXX@gmail.com is RESET”

second and third line, see next post.

XXXXXXXX@gmail.com is my chat partner.
I can read it, but I can’t tell how it helps me. Do you need something else?

second line:
2020-08-26T00:02:31.698Z core/event INFO “DC_EVENT_INFO” 0 “src\e2ee.rs:69: peerstate for “XXXXXXXX@gmail.com” is no-encrypt”

third line:
2020-08-26T00:02:31.699Z core/event INFO “DC_EVENT_INFO” 0 “src\job.rs:195: saving job for Smtp-thread: Job { job_id: 0, action: SendMsgToSmtp, foreign_id: 3073, desired_timestamp: 1598400151, added_timestamp: 1598400151, tries: 0, param: Params { inner: {Recipients: “XXXXXXXX@gmail.com\u{1e}XX@XXXXX.XX”, File: “$BLOBDIR/Mr.w9rnvt1boe3.ghzxcznwswi@XXXXXX”} }, pending_error: None }”

You can select it and reformat as “preformatted text”. Probably makes sense to disable this “spam protection”, I haven’t seen it abused yet.

I can read it, but I can’t tell how it helps me. Do you need something else?

Both lines say that DC thinks your contact has turned the setting “Prefer end-to-end encryption” off or sent the last mail to you from the client that does not support autocrypt.

You can check it by opening the headers of the last mail from your contact in a mail client and looking for line:

Autocrypt: addr=email@example.com; prefer-encrypt=mutual; keydata=...

If there is no such header, then your contact uses a client without autocrypt support. If there is Autocrypt header, but it does not contain prefer-encrypt=mutual, then your contact has “Prefer end-to-end encryption” disabled.

perfect answer, let me check. thanks in advance. mik