How to Set Up Multi-Device

Step-by-step guide for using Vauchi on multiple devices.

Adding a device is less like copying a file and more like introducing two people who then keep each other up to date. The introduction has to happen once, in a way no eavesdropper can fake — after that, your phone and your laptop hold the same identity and sync between themselves. This guide covers the introduction, and what to do when a device is lost.

Prerequisites

  • Your existing device with Vauchi set up
  • A new device with Vauchi installed (but not set up)
  • Both devices have internet connectivity

Linking a New Device

On your existing device:

Mobile (iOS/Android):

  1. Open Vauchi
  2. Go to Settings (gear icon)
  3. Tap Devices
  4. Tap Link New Device
  5. A QR code appears (valid for 5 minutes)

Desktop:

  1. Open Vauchi Desktop
  2. Go to Devices (from the sidebar)
  3. Click Link New Device
  4. A QR code and data string appear (valid for 5 minutes)

TUI:

  1. Open Vauchi TUI
  2. Press d to go to Devices
  3. Press l to generate a link
  4. A QR code and data string appear in an overlay

CLI:

vauchi device link

A QR code and data string are displayed in the terminal.

Step 2: Join on New Device

On your new device:

Mobile (iOS/Android):

  1. Open Vauchi
  2. On the welcome screen, tap Join Existing Identity
  3. Point your camera at the QR code from Step 1
  4. Verify the confirmation code matches on both devices
  5. Wait for the linking to complete

Desktop:

  1. Open Vauchi Desktop
  2. On the setup screen, click Join Existing Identity
  3. Paste the data string from the existing device
  4. Verify the confirmation code matches on both devices
  5. Click Confirm to complete linking

CLI:

vauchi device join <data-string>

Then on the existing device, pass the encrypted request data from the new device:

vauchi device complete <request-data>

That six-digit code is doing real work

Both devices show a short confirmation code like 123-456. It isn't a password or a formality — each device computes it independently from the keys they just agreed on, so the numbers can only match if the two devices really negotiated with each other and nobody slipped into the middle. Matching codes are your proof of no man-in-the-middle. If they differ, stop and start over.

Step 3: Confirm

Both devices should show:

  • Your existing device: "Device linked successfully"
  • Your new device: "Welcome back, [Your Name]"

Your new device is now synced with your identity.

Verifying Setup

After linking:

On New Device

  1. Go to Contacts — your contacts should appear
  2. Go to Home — your contact card should appear
  3. Go to Settings > Devices — both devices should be listed

On Existing Device

  1. Go to Settings > Devices
  2. You should see both devices listed
  3. Your new device shows its platform and last sync time

Syncing Data

Sync is request-and-response, not a live broadcast — each device asks the relay for what's waiting and sends what's new. So changes land near-instantly when both devices are online, and catch up the moment a sleeping device wakes. Throughout, the relay only ever handles end-to-end encrypted blobs; it never sees your plaintext.

  • Near-instant: When both devices are online
  • On app open: When you open the app
  • Manual: Pull to refresh or Settings > Sync Now

What Syncs

DataSyncs?
Your contact cardYes
Your contactsYes
Visibility settingsYes
App preferencesYes

Managing Devices

Viewing All Devices

Mobile/Desktop: Go to Settings > Devices to see all linked devices. Your current device is marked.

TUI: Press d to open the Devices screen. Navigate with j/k or arrow keys. Current device is marked [this device].

CLI:

vauchi device list

Revoking a Device

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

Mobile/Desktop:

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

TUI:

  1. Press d to open Devices
  2. Navigate to the device with j/k
  3. Press r to revoke
  4. Press y to confirm

CLI:

vauchi device revoke <device-id>

Warning

You can't revoke the device in your hand — a chair can't be pulled out from under the person sitting in it. Revoke from another linked device.

Danger

Revocation is immediate and permanent. The revoked device loses all access.

Troubleshooting

QR codes are valid for 5 minutes. If expired:

  1. On your existing device, generate a new link code
  2. Scan or paste the new code quickly

New Device Not Syncing

  1. Check internet on both devices
  2. Wait a few minutes for initial sync
  3. Pull to refresh on the new device
  4. Check Settings > Sync for last sync time

"Too Many Devices" Error

Ten is the ceiling — generous, but a ceiling. An eleventh device has to wait for a seat:

  1. Go to Settings > Devices
  2. Revoke a device you no longer use
  3. Try linking the new device again

Migrating to a New Phone

  1. Keep your old phone accessible
  2. Follow the steps above to link your new phone
  3. Wait for sync to complete
  4. Optionally, revoke your old phone

This is the cleanest migration path.

Option 2: Backup & Restore

If you can't access your old phone:

  1. Restore from an encrypted backup
  2. See How to Recover Your Account

Security Notes

  • Each device has its own derived keys
  • Revoking a device invalidates its keys immediately
  • Up to 10 devices per identity; revoke one to make room for an eleventh
  • The relay only forwards end-to-end encrypted data, routed by daily-rotating mailbox tokens — never your plaintext, identity, or IP
  • Link codes expire after 5 minutes
  • A 6-digit confirmation code, computed independently on both devices, proves you're linking the right two — no man-in-the-middle

For more on security, see Multi-Device Feature.