Rust crypto: only one account in the store

[moufmouf]

Hey!

I'm currently trying to create a Matrix client inside WorkAventure.

So far, I managed to set up Rust crypto and everything seems to run fine. I can log into my application using my "john.doe" user and the connection to Synapse is successful.

However, if I log out, and log in with another used ("jane.doe"), I'm getting the following error during the call to await client.initRustCrypto();:

the account in the store doesn't match the account in the constructor: expected @john.doe:matrix.workadventure.localhost:ULlGg2Bzxv, got @jane.doe:matrix.workadventure.localhost:aUM4pNrpuo

I'm quite new to Matrix so I don't know if I stumbled on a bug or if there is something I don't understand.

My expectation was that a store could contain several accounts.

Am I supposed to purge the store when someone logs out?

When I look at the code, I see that the name of the indexedDb we use to store the crypto keys is always the same (it is RUST_SDK_STORE_PREFIX):

matrix-js-sdk/src/client.ts

Lines 2320 to 2329 in 48d4f1b

	const rustCrypto = await RustCrypto.initRustCrypto(
	this.logger,
	this.http,
	userId,
	deviceId,
	this.secretStorage,
	this.cryptoCallbacks,
	useIndexedDB ? RUST_SDK_STORE_PREFIX : null,
	this.pickleKey,
	);

If the store can only contain one user, wouldn't it make sense to create one store per user?

Something like:

        const rustCrypto = await RustCrypto.initRustCrypto(
            this.logger,
            this.http,
            userId,
            deviceId,
            this.secretStorage,
            this.cryptoCallbacks,
-           useIndexedDB ? RUST_SDK_STORE_PREFIX : null,
+           useIndexedDB ? RUST_SDK_STORE_PREFIX + userId : null,
            this.pickleKey,
        );

Or is there something I don't understand?

Note: I will happily contribute a PR if this is something that needs fixing.

[richvdh]

Am I supposed to purge the store when someone logs out?

yes, exactly so. The idea is that if you log out, you don't want a lot of sensitive data hanging around in the data store.

I'm going to close this issue now, as hopefully this resolves it.