MLS Chat History support (Backup, ~~gossip~~, re-decryption?) WPD: Demo

[uhoreg]

Work Package 4

This is an epic issue. List the individual issues below:

MLS does not have any support for decrypting historical messages, either on newly-logged-in devices, or re-decrypting messages, and in fact, tries to prevent it, for security reasons. However, users expect to be able to decrypt historical messages. This work package is about enabling this capability.

Goal: Video demo, update PR

Linked Issues

Beta Give feedback

1. MLS POC WP4 | determine what information needs to be saved to decrypt historical messages vector-im/element-meta#1686
   +0
   
2. MLS POC WP4 | implement data structures and functions in Rust for decrypting historical messages vector-im/element-meta#1687
   +0
   
3. MLS POC WP4 | update DMLS group to automatically create data structure for historical messages, store it, and import/export vector-im/element-meta#1692
   +0
   
4. MLS POC WP4 | allow decrypting messages using data structure for historical messages vector-im/element-meta#1787
   +0
   
5. MLS POC WP4 | update wasm binding for storing/importing/exporting data structure for historical messages vector-im/element-meta#1788
   +0
   
6. MLS POC WP4 | determine how to store in key backup #1789
   +0
   
7. MLS POC WP4 | possibly make synapse changes vector-im/element-meta#1790
   +0
   
8. MLS POC WP4 | update js-sdk to backup/restore keys vector-im/element-meta#1791
   +0
   
9. support backfilling epochs from gappy sync in js-sdk?
10. MLS POC WP4 | record demo and update demo site vector-im/element-meta#1793
    +0
    

Deliverable

• video demo