Multi-Device Sync

A single device holding your only identity is a single point of failure — and single points of failure have a way of failing at the worst moment. A second device changes the whole risk calculation: lose your phone and it's an inconvenience, not a catastrophe. One identity, several windows onto it, kept quietly in step.

How it works

Every device you link shares the same identity. A change on one shows up on all of them.

┌─────────────────┐                               
│  Your Identity  │                               
│                 │                               
│                 │                               
│ ┌─────────────┐ │                               
│ │             │ │                               
│ │ Master Seed ├─┼───┬────┐                      
│ │             │ │   │    │                      
│ └──────┬──────┘ │   └────┼──────────────┐       
│        │        │        │              │       
└────────┼────────┘        │              │       
         │                 │              │       
         │                 │              │       
         │                 │              │       
┌────────┼─────────────────┼──────────────┼──────┐
│        │           Devices              │      │
│        │                 │              │      │
│        ▼                 ▼              ▼      │
│ ┌─────────────┐     ┌────────┐     ┌─────────┐ │
│ │             │     │        │     │         │ │
│ │    Phone    │     │ Tablet │     │ Desktop │ │
│ │             │     │        │     │         │ │
│ └─────────────┘     └────▲───┘     └────▲────┘ │
│                          │              │      │
└──────────────────────────┼──────────────┼──────┘
                           │              │       
                           │              │       
                           │              │       
  ┌─────────────┐          │              │       
  │             │          │              │       
  │      R      │◄─────────┴──────────────┘       
  │             │                                 
  └─────────────┘

You'll need: your existing device set up, the new device with Vauchi installed, and both online.

  1. On the existing device, go to Settings > Devices
  2. Tap Link New Device
  3. A QR code appears — valid for 5 minutes
  4. On the new device, install Vauchi
  5. Choose Join Existing Identity
  6. Scan the QR (or paste the data string on desktop/CLI)
  7. Check the confirmation code matches on both screens
  8. Confirm

Both devices now share your identity and sync on their own.

The confirmation code

Both devices show a 6-digit code (e.g. 123-456), derived cryptographically from the shared link data — only the two devices in the link can compute it. Matching codes mean nobody slipped into the middle. It takes a second to check and closes the one gap a network attacker might hope for; check it.

How many devices

  • Maximum: 10 per identity — more than most people own, few enough to keep the circle of trust small
  • Minimum: 1

Need an 11th? Revoke one first.

Platform support

PlatformLink (generate)Join (scan/paste)Manage devices
iOSPlannedPlannedPlanned
AndroidPlannedPlannedPlanned
DesktopYesYes (paste)Yes
TUIYesPlannedYes
CLIYesYesYes

Managing devices

See what's linked. Settings > Devices lists every device — name, platform, and status — with your current one marked.

Revoke a device that's lost, stolen, or retired:

  1. On another linked device, go to Settings > Devices
  2. Find the one to remove
  3. Tap Revoke and confirm

Warning

You can't revoke the device you're holding — use another linked device to cut off a lost one. (Which is itself a quiet argument for having a second device.)

A revoked device loses access instantly, can no longer send or receive updates, and can't be re-linked without starting fresh.

What syncs, and how

Changes sync automatically when you're online, end-to-end encrypted, with the relay none the wiser. Offline changes catch up when you reconnect.

DataSyncs?
Your contact cardYes
Your contactsYes
Visibility settingsYes
App preferencesYes
Device-specific settingsNo

Timing: near-instant when both devices are online; a pull of anything pending whenever you open the app; and a manual Settings > Sync Now when you're impatient.

Moving to a new phone

Link it (recommended). Link the new phone as a device, let it sync, then optionally revoke the old one. This preserves each device's own keys and hands over cleanly.

Or restore from backup. Create an encrypted backup on the old phone; restore it on the new one. Ideal when the old phone is already gone.

Troubleshooting

Sync isn't working. Check connectivity on both devices, make sure the app is open on each, try a manual sync, and confirm the device wasn't revoked.

A device won't appear. Give sync a few minutes, restart the app on both ends, make sure the link code hasn't expired (5 minutes), and generate a fresh one if needed.

Security

  • Each device holds its own keys, derived from your master seed
  • Revoking a device invalidates its keys immediately
  • The relay never sees plaintext
  • Device-to-device traffic is end-to-end encrypted
  • Confirmation codes block man-in-the-middle attempts during linking