Multi-Device Sync

Use Vauchi on multiple devices with the same identity.

How It Works

All your devices share the same identity and stay in sync. Changes made on one device appear on all others.

graph TB
    subgraph "Your Identity"
        ID[Master Seed]
    end

    subgraph "Devices"
        D1[Phone]
        D2[Tablet]
        D3[Desktop]
    end

    ID --> D1
    ID --> D2
    ID --> D3

    D1 <--> |Encrypted Sync| R[Relay Server]
    D2 <--> R
    D3 <--> R

Linking a New Device

Prerequisites

  • Your existing device with Vauchi set up
  • The new device with Vauchi installed
  • Both devices online

Steps

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

Both devices now share your identity and sync automatically.

Confirmation Code

When linking, both devices display a 6-digit code (e.g., 123-456). This code is derived cryptographically from the shared link data — only the two devices involved can compute it. If the codes match, you know the link is authentic.

Device Limits

  • Maximum: 10 devices per identity
  • Minimum: 1 device (your primary)

If you need to add an 11th device, revoke an existing one first.

Platform Support

PlatformLink (Generate)Join (Scan/Paste)Manage Devices
iOSPlannedPlannedPlanned
AndroidPlannedPlannedPlanned
DesktopYesYes (paste)Yes
TUIYesPlannedYes
CLIYesYesYes

Managing Devices

Viewing Linked Devices

  1. Go to Settings > Devices
  2. See all linked devices
  3. Your current device is marked

Each device shows:

  • Device name
  • Platform (iOS, Android, Desktop, CLI, TUI)
  • Status (active, revoked)

Revoking a Device

If a device is lost, stolen, or no longer needed:

  1. Go to Settings > Devices on another device
  2. Find the device to revoke
  3. Tap Revoke
  4. Confirm the action

Warning

You cannot revoke your current device. Use another linked device to revoke a lost one.

A revoked device:

  • Loses access to your identity immediately
  • Cannot send or receive updates
  • Cannot be re-linked without starting fresh

How Sync Works

  • Changes sync automatically when online
  • Sync uses end-to-end encryption
  • The relay server cannot read your data
  • Offline changes sync when connectivity returns

What Syncs

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

Sync Frequency

  • Real-time: When both devices are online
  • On app open: Pulls any pending changes
  • Manual: Pull to refresh or Settings > Sync Now

Migration

Moving to a New Phone

Option 1: Device Linking (Recommended)

  1. On old phone: Link the new phone as a device
  2. Wait for sync to complete
  3. On old phone: Revoke the old phone (optional)

Option 2: Backup & Restore

  1. On old phone: Create an encrypted backup
  2. On new phone: Restore from backup

Device linking is preferred because it preserves device-specific keys and ensures a clean handoff.

Troubleshooting

Sync Not Working

  1. Check internet connectivity on both devices
  2. Ensure both devices have the app open
  3. Try manual sync (Settings > Sync Now)
  4. Check that the device hasn't been revoked

Device Not Appearing

  1. Wait a few minutes for sync
  2. Restart the app on both devices
  3. Check the link code hasn't expired (5 minutes)
  4. Try generating a new link code

Security

  • Each device has its own keys derived from your master seed
  • Revoking a device invalidates its keys immediately
  • The relay server never sees plaintext data
  • Device-to-device communication is end-to-end encrypted
  • Confirmation codes prevent man-in-the-middle attacks during linking