Also remove "you can now call 'configure'" from the REPL output, probably users of the REPL tool can
read the code documentation to know when 'configure' should be run.
- DC_CHAT_TYPE_BROADCAST does no longer exist
- DC_CHAT_TYPE_MAILINGLIST is no longer always read-only
- avoid double docs by moving everything to DC_CHAT_TYPE group
(here, things were also updated recently)
It is a follow-up to https://github.com/chatmail/core/pull/7643
Event is not emitted when the transports are modified on this device
and we should consistently say that this event is not only for testing.
There are quite some unneeded stock strings; this PR removes some of
them. None of these stock strings were actually set by the UI, or even
have translations in Transifex.
- We don't have AEAP anymore.
- The "I added/removed member" and "I left the group" strings are
anyways not meant to be shown to the user. Also, starting to translate
them now would leak the device language.
BREAKING CHANGE: This can theoretically be a breaking change because a
UI could reference one of the removed stock strings, so I marked it as
breaking just in case.
- Db encryption does nothing with blobs, so fs/disk encryption is recommended.
- Isolation from other apps is needed anyway.
- Experimental database encryption was removed on iOS and Android.
- Delta Touch is using CFFI API with a manually entered password because Ubuntu Touch does not offer
filesystem or disk encryption, but we don't want new users of these APIs, such as bot developers.
Add a stock string `%1$s invited you to join this channel.\n\nWaiting
for the device of %2$s to reply…`, which is shown when a user starts to
join a channel.
I did _not_ add an equivalent to `%1$s replied, waiting for being added
to the group…`, which is shown when vg-auth-required was received. I
don't think that this would add any information that's interesting to
the user, other than 'something is happening, hang on'. And the more
text on the screen, the less likely that anyone reads it. But if others
think differently, we can also add it.
With this PR, joining a channel looks like this:
```
Msg#2003: info (Contact#Contact#Info): Messages are end-to-end encrypted. [NOTICED][INFO]
Msg#2004: info (Contact#Contact#Info): Alice invited you to join this channel.
Waiting for the device of Alice to reply… [NOTICED][INFO]
Msg#2007🔒: (Contact#Contact#2001): You joined the channel. [FRESH][INFO]
```
New APIs are JSON-RPC method stop_background_fetch(),
Rust method Accounts.stop_background_fetch()
and C method dc_accounts_stop_background_fetch().
These APIs allow to cancel background fetch early
even before the initially set timeout,
for example on Android when the system calls
`Service.onTimeout()` for a `dataSync` foreground service.
`Contact::get_color()` returns gray if own keypair doesn't exist yet and we don't want any UIs
displaying it. Keypair generation can't be done in `get_color()` or `get_by_id_optional()` to avoid
breaking Core tests on key import. Also this makes the API clearer, pure getters shouldn't modify
any visible state.
Follow-up for https://github.com/chatmail/core/pull/7042, part of
https://github.com/chatmail/core/issues/6884.
This will make it possible to create invite-QR codes for broadcast
channels, and make them symmetrically end-to-end encrypted.
- [x] Go through all the changes in #7042, and check which ones I still
need, and revert all other changes
- [x] Use the classical Securejoin protocol, rather than the new 2-step
protocol
- [x] Make the Rust tests pass
- [x] Make the Python tests pass
- [x] Fix TODOs in the code
- [x] Test it, and fix any bugs I find
- [x] I found a bug when exporting all profiles at once fails sometimes,
though this bug is unrelated to channels:
https://github.com/chatmail/core/issues/7281
- [x] Do a self-review (i.e. read all changes, and check if I see some
things that should be changed)
- [x] Have this PR reviewed and merged
- [ ] Open an issue for "TODO: There is a known bug in the securejoin
protocol"
- [ ] Create an issue that outlines how we can improve the Securejoin
protocol in the future (I don't have the time to do this right now, but
want to do it sometime in winter)
- [ ] Write a guide for UIs how to adapt to the changes (see
https://github.com/deltachat/deltachat-android/pull/3886)
## Backwards compatibility
This is not very backwards compatible:
- Trying to join a symmetrically-encrypted broadcast channel with an old
device will fail
- If you joined a symmetrically-encrypted broadcast channel with one
device, and use an old core on the other device, then the other device
will show a mostly empty chat (except for two device messages)
- If you created a broadcast channel in the past, then you will get an
error message when trying to send into the channel:
> The up to now "experimental channels feature" is about to become an officially supported one. By that, privacy will be improved, it will become faster, and less traffic will be consumed.
>
> As we do not guarantee feature-stability for such experiments, this means, that you will need to create the channel again.
>
> Here is what to do:
> • Create a new channel
> • Tap on the channel name
> • Tap on "QR Invite Code"
> • Have all recipients scan the QR code, or send them the link
>
> If you have any questions, please send an email to delta@merlinux.eu or ask at https://support.delta.chat/.
## The symmetric encryption
Symmetric encryption uses a shared secret. Currently, we use AES128 for
encryption everywhere in Delta Chat, so, this is what I'm using for
broadcast channels (though it wouldn't be hard to switch to AES256).
The secret shared between all members of a broadcast channel has 258
bits of entropy (see `fn create_broadcast_shared_secret` in the code).
Since the shared secrets have more entropy than the AES session keys,
it's not necessary to have a hard-to-compute string2key algorithm, so,
I'm using the string2key algorithm `salted`. This is fast enough that
Delta Chat can just try out all known shared secrets. [^1] In order to
prevent DOS attacks, Delta Chat will not attempt to decrypt with a
string2key algorithm other than `salted` [^2].
## The "Securejoin" protocol that adds members to the channel after they
scanned a QR code
This PR uses the classical securejoin protocol, the same that is also
used for group and 1:1 invitations.
The messages sent back and forth are called `vg-request`,
`vg-auth-required`, `vg-request-with-auth`, and `vg-member-added`. I
considered using the `vc-` prefix, because from a protocol-POV, the
distinction between `vc-` and `vg-` isn't important (as @link2xt pointed
out in an in-person discussion), but
1. it would be weird if groups used `vg-` while broadcasts and 1:1 chats
used `vc-`,
2. we don't have a `vc-member-added` message yet, so, this would mean
one more different kind of message
3. we anyways want to switch to a new securejoin protocol soon, which
will be a backwards incompatible change with a transition phase. When we
do this change, we can make everything `vc-`.
[^1]: In a symmetrically encrypted message, it's not visible which
secret was used to encrypt without trying out all secrets. If this does
turn out to be too slow in the future, then we can remember which secret
was used more recently, and and try the most recent secret first. If
this is still too slow, then we can assign a short, non-unique (~2
characters) id to every shared secret, and send it in cleartext. The
receiving Delta Chat will then only try out shared secrets with this id.
Of course, this would leak a little bit of metadata in cleartext, so, I
would like to avoid it.
[^2]: A DOS attacker could send a message with a lot of encrypted
session keys, all of which use a very hard-to-compute string2key
algorithm. Delta Chat would then try to decrypt all of the encrypted
session keys with all of the known shared secrets. In order to prevent
this, as I said, Delta Chat will not attempt to decrypt with a
string2key algorithm other than `salted`
BREAKING CHANGE: A new QR type AskJoinBroadcast; cloning a broadcast
channel is no longer possible; manually adding a member to a broadcast
channel is no longer possible (only by having them scan a QR code)
We already have both rand 0.8 and rand 0.9
in our dependency tree.
We still need rand 0.8 because
public APIs of rPGP 0.17.0 and Iroh 0.35.0
use rand 0.8 types in public APIs,
so it is imported as rand_old.
If we use modules (which are actually namespaces), we can use shorter names. Another approach is to
only use modules for internal code incapsulation and use full names like deltachat-ffi does.
Create unprotected group in test_create_protected_grp_multidev
The test is renamed accordingly.
SystemMessage::ChatE2ee is added in encrypted groups
regardless of whether they are protected or not.
Previously new encrypted unprotected groups
had no message saying that messages are end-to-end encrypted
at all.
MX record lookup was only used to detect Google Workspace domains.
They can still be configured manually.
We anyway do not want to encourage creating new profiles
with Google Workspace as we don't have Gmail OAUTH2 token anymore
and new users can more easily onboard with a chatmail relay.
