Why history messages are not visible to invited users in encrypted rooms even after settings says it should

[MrJai]

This issue is a copy of Element-web # 21072. I am asking it here again because this feature is working in Element-web and Element-Desktop but is still not available in Element-ios and Element-android.

Now the question is why this feature is available in Element Web/Desktop and not in Element Mobile. Is there a limitation or is it not possible to share keys from iOS/Android? I am asking this because the product I am planning to develop is a 100% mobile application (at least for now).

Original Question from Element-Web vector-im/element-web#21072

Steps to reproduce

Background:

We are trying to implement a mobile app with end-to-end encryption but providing past messages history to new members joining the group is a key thing we need.

Plan:

We were planning to use olm/megolm and matrix-SDK, and then we tried to test our use cases with Element.io (web, desktop, ios, android) versions.

Issue:

History wasn’t available for new users in a room. Since then we have been studying it, the documentation says it should work by sharing keys, but it is not working with Element clients. We have tried all possibilities of inviting a user from different clients and then accepting the invitation from different clients but the new user is either not able to see the history at all or it is broken (like some messages say keys are not shared, or not possible to show).

We are following these issues from different related repositories, they are also talking about similar or same issues and are not able to fix the issue, but we are not sure what are the reasons for not being able to fix/implement this feature of sharing history with new group member by sharing the keys.

element-web#2286

element-web#2713

matrix-react-sdk#5763

Request:

It will be a huge favor if anyone of you can document the reasons why we have not been able to implement this feature till now, what are the issues that even when the client and the documentation say that it should work, it is still broken.

Outcome

What did you expect?

Every new member in the end-to-end encrypted private room should be able to see the history when in the settings we have selected "Anyone" for who can watch the history.

What happened instead?

Either it doesn't show anything as if it is a new room and there is no previous message, or it shows waiting for messages/keys, or it shows other warnings/information but never shows the actual messages.

Your phone model

iPhone 12 Pro Max

Operating system version

No response

Application version

Element version: 1.10.1 Olm version: 3.2.8

Homeserver

matrix.org

Will you send logs?

No

[saibotk]

I think this is already tracked in #4947

But nonetheless seems like a really important feature (especially since this won't magically make past megolm sessions shareable if I understood correctly).

[pixlwave]

Hi, thanks for opening this issue @MrJai. I've asked internally and adding this functionality to the SDKs is on the todo list but the changes will also affect the existing UX in various ways which will also need time to be looked at. So unfortunately it isn't going to be a quick item to implement. I'm going to close this as a duplicate of element-hq/element-web#4947, if you feel that issue is lacking in any way, please feel free to add to it.