How to Exchange Contacts

Step-by-step guide for exchanging contact cards with other Vauchi users.

Prerequisites

• Both you and the other person have Vauchi installed
• You're physically together (proximity verification required)
• Both devices have working cameras

QR Code Exchange

Both people show and scan each other's QR codes. This ensures fresh encryption keys are used for every exchange (forward secrecy).

Step 1: Open Exchange

1. Open Vauchi
2. Tap the Exchange tab at the bottom

Step 2: Show Your QR Code

1. Tap Show My QR Code
2. A QR code appears on your screen
3. Show it to the other person

Step 3: They Scan Your Code

1. The other person points their camera at your QR code
2. Their device confirms a successful scan

Step 4: Scan Their Code

1. Tap Scan QR Code
2. Point your camera at their QR code
3. Wait for the scan to complete

Step 5: Confirm

Both devices show "Exchange Successful"

You now have each other's contact cards.

Troubleshooting

QR Code Won't Scan

1. Lighting: Make sure the QR code is well-lit
2. Stability: Hold both devices steady
3. Distance: Try moving closer or farther
4. Clean lens: Wipe your camera lens
5. Refresh: Generate a new QR code (they expire after 5 minutes)

Exchange Keeps Failing

1. Check internet connectivity on both devices
2. Ensure the QR code hasn't expired (5-minute limit)
3. Restart the app on both devices
4. Try a fresh QR code

After Exchange

Once exchange completes:

• They appear in your Contacts list
• You can see their card (fields they've shared)
• They can see your card (fields you've shared)
• Future changes sync automatically

Next Steps

• Control what they see
• Verify their identity

Security Notes

• QR codes expire after 5 minutes (replay protection)
• Both parties must scan each other's QR codes (mutual verification)
• Each exchange uses fresh ephemeral keys (forward secrecy)
• Exchange uses encrypted key agreement
• The relay never sees unencrypted data

For more on security, see Encryption.