Contact discovery

[rubdos]

Small patch, but depends on #50 because I didn't want to get into String-hell again :'-)

Will rebase once I get #50 finished.

[Be-ing]

#50 has been merged and this has some merge conflicts now. Could you rebase?

[rubdos]

#50 has been merged and this has some merge conflicts now. Could you rebase?

It's quite a bit of conflicts, sadly. I'll rebase when I work again on contact discovery; except if you want to continue this really soon?

[Be-ing]

if you want to continue this really soon?

Rebasing someone else's branch isn't a very nice way to get started in a new codebase.

[rubdos]

So, I've rebased this now, but retrieveDirectory / /v1/directory/tokens seems like it's gone from the Signal client. We probably want to drop this and implement the new contact discovery protocol with attestation.

[rubdos]

the new contact discovery protocol with attestation.

Result of some investigative work:

Android's ContactDiscoveryRefreshV1.java contains the currently working logic to do contact lookup. However, Signal has been working on a V2, ContactDiscoveryRefreshV2.kt (notice Kotlin), tied to https://github.com/signalapp/ContactDiscoveryService. This version 2 has no endpoint on the production servers yet, but it has a lot of recent activity, and might replace V1 sooner than we want. Version 2 also has some components in Signal-Client, such that we don't have to implement everything ourselves.

So either we implement both, or we wait a bit longer until v2 is moved into production.

[rubdos]

In other news: these Rust components in libsignal-client require ecdsa ^0.13, which transitively depends on Rust 2021 and is as such currenly unusable in Whisperfish (because we're still on 1.52-dev, which on itself is not that old... come on library devs, please don't do this...)

Downgrading those versions leads to other impossibilities (ecdsa's feature serde only exists in 0.13).

[rubdos]

This stuff is completely deprecated and disfunctional by now. We should implement the new PNI system instead.