Replaces the Google Drive backup flow (#528) with deterministic key
derivation. The user's Nostr identity IS their Google account — no
encrypted blobs to store, no backup events to publish, nothing for
Google or any third party to retain.
privkey = SHA-256("wisp-account-v1:" || sub || ":" || accountIndex)
Properties:
- Same Google account always derives the same nsec on any device
- No backup to lose: signing in regenerates the keys
- No `drive.appdata` OAuth scope, no scary Drive consent dialog
- Anyone with access to the Google account can derive every nsec.
Bounded by Google account security — same trade-off as #528, with
a much simpler attack surface and no third-party storage layer
Discovery on sign-in:
- Derive candidate keypairs for indices 0..15 from the user's `sub`
- One REQ to relay.damus.io, relay.primal.net, nos.lol, nostr.wine,
relay.wisp.talk, relay.ditto.pub asking for kind 0/3/10002 events
from those pubkeys
- Pubkeys with any activity = "in use" accounts that go in the chooser;
avatar + display name come from the same kind-0 events
- "Create another account" derives the next-unused index
Code shrinkage: DriveBackupService is gone, BackupCrypto's encryption
helpers are gone, the play-services-auth dependency is gone, and the
Drive-related ProGuard rules are gone. The whole flow is ~200 fewer
lines than #528 and easier to audit — the derivation is one line of
SHA-256.
Splash button switches to Google's dark-mode brand variant (#131314
container, full-color G, #8E918F stroke) per Sign in with Google spec.
No migration needed: nobody is on the #528 flow yet.
Barry Deen
3d3c6e12ef