Close https://github.com/chatmail/core/issues/7396. Before reviewing,
you should read the issue description of
https://github.com/chatmail/core/issues/7396.
I recommend to review with hidden whitespace changes.
TODO:
- [x] Implement the new protocol
- [x] Make Rust tests pass
- [x] Make Python tests pass
- [x] Test it manually on a phone
- [x] Print the sent messages, and check that they look how they should:
[test_secure_join_group_with_mime_printed.txt](https://github.com/user-attachments/files/24800556/test_secure_join_group.txt)
- [x] Fix bug: If Alice has a second device, then Bob's chat won't be
shown yet on that second device. Also, Bob's contact isn't shown in her
contact list. As soon as either party writes something into the chat,
the that shows up and everything is fine. All of this is still a way
better UX than in WhatsApp, where Bob always has to write first 😂
Still, I should fix that.
- This is actually caused by a larger bug: AUTH tokens aren't synced if
there is no corresponding INVITE token.
- Fixed by 6b658a0e0
- [x] Either make a new `auth_tokens` table with a proper UNIQUE bound,
or put a UNIQUE bound on the `tokens` table
- [x] Benchmarking
- [x] TODOs in the code, maybe change naming of the new functions
- [x] Write test for interop with older DC (esp. that the original
securejoin runs if you remove the &v=3 param)
- [x] From a cryptography perspective, is it fine that vc-request is
encrypted with AUTH, rather than a separate secret (like INVITE)?
- [x] Make sure that QR codes without INVITE work, so that we can remove
it eventually
- [x] Self-review, and comment on some of my code changes to explain
what they do
- [x] ~~Maybe use a new table rather than reusing AUTH token.~~ See
https://github.com/chatmail/core/pull/7754#discussion_r2728544725
- [ ] Update documentation; I'll do that in a separate PR. All necessary
information is in the https://github.com/chatmail/core/issues/7396 issue
description
- [ ] Update tests and other code to use the new names (e.g.
`request-pubkey` rather than `request` and `pubkey` rather than
`auth-required`); I'll do that in a follow-up PR
**Backwards compatibility:**
Everything works seamlessly in my tests. If both devices are updated,
then the new protocol is used; otherwise, the old protocol is used. If
there is a not-yet-updated second device, it will correctly observe the
protocol, and mark the chat partner as verified.
Note that I removed the `Auto-Submitted: auto-replied` header from
securejoin messages. We don't need it ourselves, it's a cleartext header
that leaks too much information, and I can't see any reason to have it.
---------
Co-authored-by: iequidoo <117991069+iequidoo@users.noreply.github.com>
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]
```
Fix#7435
For most messages, `calc_sort_timestamp()` makes sure that they are at the correct place; esp. that they are not above system messages or other noticed/seen messages.
Most callers of `add_info_msg()`, however, didn't call `calc_sort_timestamp()`, and just used `time()` or `smeared_time()` to get the sort timestamp. Because of this, system messages could sometimes wrongly be sorted above other messages.
This PR fixes this by making the sort timestamp optional in `add_info_msg*()`. If the sort timestamp isn't passed, then the message is sorted to the bottom of the chat. `sent_rcvd_timestamp` is not optional anymore, because we need _some_ timestamp that can be shown to the user (most callers just pass `time()` there).
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)
Flakiness was introduced in e7348a4fd8.
This change removes a call to joining_chat_id() which created a chat,
now we check for existing group chat
without creating it if it does not exist.
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.
this PR adds a info message "messages are end-to-end-encrypted" also for
chats created by eg. vcards. by the removal of lock icons, this is a
good place to hint for that in addition; this is also what eg. whatsapp
and others are doing
the wording itself is tweaked at
https://github.com/deltachat/deltachat-android/pull/3817 (and there is
also the rough idea to make the message a little more outstanding, by
some more dedicated colors)
~~did not test in practise, if this leads to double "e2ee info messages"
on secure join, tests look good, however.~~ EDIT: did lots of practise
tests meanwhile :)
most of the changes in this PR are about test ...
ftr, in another PR, after 2.0 reeases, there could probably quite some
code cleanup wrt set-protection, protection-disabled etc.
---------
Co-authored-by: Hocuri <hocuri@gmx.de>
Part of #6884.
The channel owner will not be notified in any way that you left, they
will only see that there is one member less.
For the translated stock strings, this is what we agreed on in the
group:
- Add a new "Leave Channel" stock string (will need to be done in UIs)
- Reword the existing "Are you sure you want to leave this group?"
string to "Are you sure you want to leave?" (the options are "Cancel"
and "Leave Group" / "Leave Channel", so it's clear what you are leaving)
(will need to be done in the deltachat-android repo, other UIs will pick
it up automatically)
- Reword the existing "You left the group." string to "You left". (done
here, I will adapt the strings in deltachat-android, too)
I adapted DC Android by pushing
6df2740884
to https://github.com/deltachat/deltachat-android/pull/3783.
---------
Co-authored-by: l <link2xt@testrun.org>
This change introduces a new type of contacts
identified by their public key fingerprint
rather than an e-mail address.
Encrypted chats now stay encrypted
and unencrypted chats stay unencrypted.
For example, 1:1 chats with key-contacts
are encrypted and 1:1 chats with address-contacts
are unencrypted.
Groups that have a group ID are encrypted
and can only contain key-contacts
while groups that don't have a group ID ("adhoc groups")
are unencrypted and can only contain address-contacts.
JSON-RPC API `reset_contact_encryption` is removed.
Python API `Contact.reset_encryption` is removed.
"Group tracking plugin" in legacy Python API was removed because it
relied on parsing email addresses from system messages with regexps.
Co-authored-by: Hocuri <hocuri@gmx.de>
Co-authored-by: iequidoo <dgreshilov@gmail.com>
Co-authored-by: B. Petersen <r10s@b44t.com>
instead of showing addresses in info message, provide an API to get the
contact-id.
UI can then make the info message tappable and open the contact profile
in scope
the corresponding iOS PR - incl. **screencast** - is at
https://github.com/deltachat/deltachat-ios/pull/2652 ; jsonrpc can come
in a subsequent PR when things are settled on android/ios
the number of parameters in `add_info_msg_with_cmd` gets bigger and
bigger, however, i did not want to refactor this in this PR. it is also
not really adding complexity
closes#6702
---------
Co-authored-by: link2xt <link2xt@testrun.org>
Co-authored-by: Hocuri <hocuri@gmx.de>
This implements new group consistency algorithm described in
<https://github.com/deltachat/deltachat-core-rust/issues/6401>
New `Chat-Group-Member-Timestamps` header is added
to send timestamps of member additions and removals.
Member is part of the chat if its addition timestamp
is greater or equal to the removal timestamp.
A user reported to me that after they left a group, they were implicitly readded, but there's no any
readdition message, so currently it looks in the chat like leaving it has no effect, just new
messages continue to arrive. The readdition probably happened because some member didn't receive the
user's self-removal message, anyway, at least there must be a message that the user is readded, even
if it isn't known by whom.
I.e. add the "Messages are guaranteed to be end-to-end encrypted from now on." message and mark the
chat as protected again because no user action is required in this case. There are a couple of
problems though:
- If the program crashes earlier than the protection is restored, the chat remains
protection-broken. But this problem already exists because `ChatId::set_protection()` is never
retried.
- If multiple old unverified messages are received, protection messages added in between don't
annihilate, so they clutter the chat.
If a message from an old contact's setup is received, the outdated Autocrypt header isn't applied,
so the contact verification preserves. But the chat protection breaks because the old message is
sorted to the bottom as it mustn't be sorted over the protection info message (which is `InNoticed`
moreover). Would be nice to preserve the chat protection too e.g. add a "protection broken" message,
then the old message and then a new "protection enabled" message, but let's record the current
behaviour first.
Received messages shouldn't mingle with just sent ones and appear somewhere in the middle of the
chat, so we go after the newest non fresh message.
But if a received outgoing message is older than some `InSeen` message, better sort the received
message purely by timestamp (this is an heuristic in order not to break the Gmail-like case
simulated by `verified_chats::test_old_message_4()`). We could place the received message just
before that `InSeen` message, but anyway the user may not notice it.
At least this fixes outgoing messages sorting for shared accounts where messages from other devices
should be sorted the same way as incoming ones.
Otherwise it's impossible to remove a member with missing key from a protected group. In the worst
case a removed member will be added back due to the group membership consistency algo.
Let's add a 1-minute tolerance to `Params::MemberListTimestamp`.
This adds to the group membership consistency algo the following properties:
- If remote group membership changes were made by two members in parallel, both of them are applied,
no matter in which order the messages are received.
- If we remove a member locally, only explicit remote member additions/removals made in parallel are
allowed, but not the synchronisation of the member list from "To". Before, if somebody managed to
reply earlier than receiving our removal of a member, we added it back which doesn't look good.
If the Inbox is fetched before the Sentbox (as done currently), messages from the Sentbox will
correctly mingle with the Inbox messages in the end. So, this commit changes message ordering only
if we already have processed outgoing messages, e.g. if we just sent them in the chat as described
in #4621. Otherwise new incoming messages are displayed somewhere in the middle of the chat which
doesn't look usable.
Correctly handle messages with old timestamps for verified chats:
* They must not be sorted over a protection-changed info message
* If they change the protection, then they must not be sorted over existing other messages, because then the protection-changed info message would also be above these existing messages.
This PR fixes this:
1. Even seen messages can't be sorted into already-noticed messages anymore. **This also changes DC's behavior in the absence of verified 1:1 chats**. Before this PR, messages that are marked as seen when they are downloaded will always be sorted by their timestamp, even if it's very old.
2. protection-changed info messages are always sorted to the bottom.
**Edit:**
3. There is an exception to rule 1: Outgoing messages are still allowed to be sorted purely by their timestamp, and don't influence old messages. This is to the problem described at [*].
Together, these rules also make sure that the protection-changed info message is always right above the message causing the change.
[*] If we receive messages from two different folders, e.g. `Sent` and `Inbox`, then this will lead to wrong message ordering in many cases. I need to think about this more, or maybe someone else has an idea. One new idea that came to my mind is:
* Always sort noticed messages under the newest info message (this PR sorts them under the newest noticed message, master sorts them purely by their sent timestamp)
* Always sort unnoticed messages under the newest noticed message (that's the same behavior as in this PR and on master)
* Always sort protection-changed info messages to the bottom (as in this PR)
However, after a talk with @link2xt we instead decided to add rule 3. (see above) because it seemed a little bit easier.
