How to sign a number in WhatsApp?

How to sign a number in WhatsApp - briefly?

To sign a number in WhatsApp, you simply need to add the plus (+) sign before the country code and then enter the phone number. For example, if you're signing a US number, you would type +1 followed by the area code and the phone number.

How to sign a number in WhatsApp - in detail?

Signing a number in WhatsApp involves several steps that ensure your message is delivered securely and authentically. Here’s a detailed guide on how to achieve this:

First, it's important to understand that WhatsApp uses end-to-end encryption for all messages sent between users. This means that only the sender and recipient can read what is sent, and nobody in between, not even WhatsApp itself. To sign a number, you need to ensure that both parties have each other’s public keys and use them to verify messages.

Step 1: Obtain Public Keys

Before you can sign your number, you'll need the recipient's public key. There are several ways to obtain this:

  • Key Exchange: You can meet in person or use a secure method (like a phone call) to exchange keys.
  • Secure Platforms: Use trusted platforms that provide secure key sharing services.

Step 2: Install a Signing App

To sign messages, you'll need an app that supports cryptographic signing. Popular choices include OpenKeychain for Android and Signal for iOS.

Step 3: Import Public Keys

Once you have the recipient’s public key, import it into your signing app:

  1. Open Your Signing App: Launch the app on your device.
  2. Import Key: Use the option to import a public key and follow the prompts. You can usually do this by scanning a QR code or manually entering the key details.

Step 4: Compose Your Message

Now that you have the necessary keys, compose your message in WhatsApp as usual:

  1. Open WhatsApp: Launch WhatsApp and select the contact to whom you want to send the signed number.
  2. Write Your Message: Type your message normally. You’ll sign it later using the signing app.

Step 5: Sign the Message

Use your signing app to sign the message:

  1. Copy the Message: Copy the text of your message from WhatsApp.
  2. Open Signing App: Go back to your signing app.
  3. Sign the Message: Paste the message into the signing app and use it to generate a signature. The app will create a unique digital signature based on the content of your message and your private key.
  4. Copy the Signature: Copy the generated signature.

Step 6: Send the Signed Message

Return to WhatsApp and append the signature to your original message:

  1. Paste the Signature: Paste the signature at the end of your message in WhatsApp.
  2. Send the Message: Hit send, and your signed message will be on its way.

Step 7: Verification (Recipient Side)

The recipient can verify the authenticity of your message using their signing app:

  1. Copy the Message and Signature: They should copy both the original message and the signature from WhatsApp.
  2. Open Their Signing App: The recipient opens their signing app.
  3. Verify the Signature: They paste the message and signature into the verification section of the app, which will confirm if the message is authentic and has not been tampered with.

By following these steps, you ensure that your messages are signed securely, providing an additional layer of trust in your communications on WhatsApp.