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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 (or on a video call)
  • Both devices have working cameras

QR Code Exchange (Standard)

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

Tip

Keep your screen brightness up and hold steady for easier scanning.

Step 3: They Scan Your Code

  1. The other person opens their camera/scanner
  2. They point it at your QR code
  3. Wait for proximity verification (you'll hear/feel a confirmation)

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.

Two-Way Exchange (Quick Version)

For faster exchange when both are ready:

  1. Both open the Exchange tab
  2. Person A shows QR → Person B scans
  3. Person B shows QR → Person A scans
  4. Done!

One-Way Sharing

To share your card without receiving theirs:

When to Use

  • Sharing business cards at conferences
  • Giving your info to someone you don't need to stay in touch with
  • Public sharing scenarios

Steps

  1. Open the Exchange tab
  2. Enable Share Only mode (toggle at top)
  3. Show your QR code
  4. They scan it
  5. They have your card; you don't have theirs

Video Call Exchange

When you can't meet in person:

Steps

  1. Start a video call with the other person
  2. You: Share your screen showing your QR code
  3. Them: Scan it from the video
  4. Switch roles — they share screen, you scan
  5. Exchange complete

Note

Video call exchange skips proximity verification. Use only with people you trust.

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)

Proximity Verification Failed

  1. Move closer: Get within 1-2 meters
  2. Reduce noise: Background noise can interfere
  3. Check audio: Ensure speakers/microphones work
  4. Try again: Sometimes it takes a second attempt

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

Security Notes

  • QR codes expire after 5 minutes (replay protection)
  • Proximity verification prevents remote attacks
  • Exchange uses encrypted key agreement
  • The relay never sees unencrypted data

For more on security, see Encryption.