Android clients hides room history from newly invited users in a room

[daniellekirkwood]

Steps to reproduce

Our customers are complaining that export of room history does not work. They expect to have new users in a room be able to see the complete message history of the room, but previous history doesn't load automatically when joining the room, and there is no sign or indications of loading nor any errors.

• Does this happen on the 'regular' Android client

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Repro:
Prerequisite:

1. Need multiple users
2. Web users & Mobile device user (Android)

Issue (1)

• Step 1: Create history between two web-users(make sure "made future room history visible to all room members." option is on).
• Step 2: Invite a third web-user to the room: Third user can't see any messages until another activity is happening (e.g. switching room back and forth, sending a message or simply receiving one). Furthermore, room history is added in chunks, and will not be complete until after several actions/activities in the room.

Issue (2)

• Step 3: Invite an Android user into the room (Android users loads the entire room history upon joining the room).
• Step 4: Android user send a message in the room.
• Step 5: (optional) Send a message or two from the other web users.
• Step 6: Invite a new web-user to the room.

New web user can only see messages AFTER the message Android user sent. IOW messages sent earlier that the first Android message will be excluded from the room history.

Outcome

What did you expect?

What happened instead?

Your phone model

No response

Operating system version

No response

Application version and app store

No response

Homeserver

No response

Will you send logs?

No

[manuroe]

I think this is because of the lack of MSC3061: Sharing room keys for past messages on android (and ios).

Existing issues:

• Sharing room keys for past messages #4153
• Sharing room keys for past messages element-ios#4947

[thoraj]

Even if Element iOS or Android does not support key sharing yet, their presence in a room should not prevent web users from sharing keys?

It sounds like these are two separate issues:

1. Presence of Android (and iOS?) devices in a room prevents key sharing between Element Web clients
2. Android and iOS devices do not support sharing keys

[benparsons]

I see this has been moved to Need info - what info is needed, and from whom?

[daniellekirkwood]

We believe this is a Crypto issue and would fall to @BillCarsonFr and team.

@BillCarsonFr is that right, what can we do to help you with this?

[BillCarsonFr]

I have to check, if by 'hides history' you mean that the message are not displayed, it's a timeline issue to be handled by platform.
If by hides history you mean that the events can't be decrypted it's expected as per @manuroe comment because sharing key history not implemented on mobile.

But this need some investigation, try to reproduce and provide more details / screenshots, hard to understand as is without investigation

[thoraj]

The symptom is that messages are not shown in the room history on the web client. The assumption is that Element Web hides the messages it is not able to decrypt.

Also note that the issue is NOT that Android (or iOS clients cannot view history). The issue is:

If a room has only Element Web devices, key sharing works as expected. I.e. newly invited users can indeed see the history in the room.

BUT if an Android device gets into the room, the next web device which gets invited to the room will NOT be able to see the history.