Fix SSSS overwrite if user never enters their SSSS key

[foldleft]

fixes: element-hq/element-web#12352

This bug caused the cross-signing panel to indicate that there were no cross-signing keys available if the user did not provide any keys, even though cross-signing is set up. This allowed the user to re-initialize the cross-signing store, destroying whatever was there previously.

Before giving keys to the client

After giving keys to the client

[turt2live]

@foldleft can this PR get a title that makes sense in a changelog please?

[turt2live]

sorry, I don't understand the problem here at all - can we also get a description of what is wrong and why we don't need to check whether keys are on the device please?

[dbkr]

Isn't this going to cause the summarisedStatus status to say it's enabled when it isn't?

[foldleft]

weirdly, crossSigningPublicKeysOnDevice seems to only be true if the private keys are also on the device. Even if the device doesn't have keys, the cross-signing can be initialised.

[dbkr]

Yeah, crossSigningPublicKeysOnDevice is whether the public key is trusted or not. My point was that in the if block just below, we'll now only hit the second case if crossSigningPrivateKeysInStorage is true but secretStorageKeyInAccount is false. So this corrects the second if block but breaks the first?

[jryans]

@foldleft Please also use title case on PRs for the changelog.

[turt2live]

seems fine from a code perspective, but it sounds like some copy/design will need to be done as part of this?

I'm relying on Dave's review here.