Element X: Two Olm Machines created in a row with same deviceId but different keys

[BillCarsonFr]

Rageshake https://github.com/element-hq/element-x-android-rageshakes/issues/1134

As part of login flow

2023-11-30T18:18:11.343073Z DEBUG matrix_sdk_crypto::machine: Created a new Olm account | crates/matrix-sdk-crypto/src/machine.rs:288 | spans: login{method="identifier and password"} > with_store{user_id="@xuanjun:matrix.org" device_id="KSBNNMTVDE" ed25519_key=yzQQLODIhkZ5v9Tku9fcvodHddLF7+os8SkyFDL1E/8 curve25519_key=y1/IrbHdpFDhdcF5fHI0QVUubNmp5EcGU9WMNL4/pAU}

Then a few seconds after from restore_session

2023-11-30T18:18:15.945739Z DEBUG matrix_sdk_crypto::machine: Created a new Olm account | crates/matrix-sdk-crypto/src/machine.rs:288 | spans: restore_session > restore_session > with_store{user_id="@xuanjun:matrix.org" device_id="KSBNNMTVDE" ed25519_key=VvjbqDo1DCfzvv/H8nHiiJ2P00uH7DscBWEaw8NZA+8 curve25519_key=/ecKBMJ1HSdIXfaTFduL/Y8pnO+oIxRjHMH83QUXlE8}

=> breaking encryption
(also causing the one time key exists problem)

2023-11-30T18:18:17.016058Z DEBUG matrix_sdk::http_client: Error while sending request: Api(Server(ClientApi(Error { status_code: 400, authenticate: None, body: Standard { kind: Unknown, message: "One time key signed_curve25519:AAAAAAAAAA0 already exists.

[stefanceriu]

Fresh logs here https://github.com/element-hq/element-x-ios-rageshakes/issues/1300#issuecomment-1883282711

[richvdh]

Note that this is a potential cause of #1415.

[BillCarsonFr]

Root cause of element-hq/element-x-ios#2287

During the login flow of EX, a first client is created with an in memory store, then after login a new client is created with a database store (the user_id is needed to create the database path).

The problem is that the first "in memory" client starts to initialize cryptography, i.e upload device keys, create cross-signing keys if needed, create backup if needed.
This will publish deviceKeys, identity keys and backup on the server.

Then the second client will try to do the same, but it will detect that keys/identities/backup are already published and this will impact bootstrap (also all the private keys of the published keys will be lost)

[BillCarsonFr]

There is a hotfix/workaround for it #3115
And a remaining task to properly refactor and not use 2 clients #3029