The Badge Archive

Three-Way Handshake

Fulfills Step 3 of GSUSA Junior Cybersecurity Basics badge requirements.

GSUSA VTK Disclaimer: Permission for use of Code.org activities is provided by Code.org, a non-profit dedicated to giving every student in every school the opportunity to learn computer science. See www.code.org.

Information needed for the badge requirement: When computers share information, they use rules called a “handshake.” A handshake is how two computers check that they are ready to work together. It’s like one computer saying, “Hi, are you ready?” and the other answering, “Yes, let’s go!” Here’s how it works step by step:

  1. One computer sends a message saying, “Can we connect?”
  2. The second computer replies, “Yes, I’m ready!”
  3. The first computer confirms, “Great, let’s start sharing!”

This quick back-and-forth makes sure both computers are ready to send and receive information safely.

Items Needed

  • VTK Three Way Handshake by GSUSA handout (includes SYN, SYN + ACK, and ACK)
  • (Optional) Whiteboard or poster board with:
    • SYN: Synchronize request
    • SYN + ACK: Acknowledgement of SYN
    • ACK: Acknowledgement of SYN + ACK, ready to proceed

Instructions

  1. Explain that computers use rules, or protocols, to communicate safely. A three-way handshake is one of these protocols.
  2. What do SYN and ACK Mean?
    • SYN (Synchronize): Computers check if they are ready to talk and synchronize their connection.
    • (Optional) Scouts can try synchronized movements, like raising their hands together, jumping, or hopping, to understand the concept of synchronization.
    • ACK (Acknowledgement): Computers confirm they’re ready to send and receive information.
  3. Scouts pair up to practice the Handshake. They follow these steps:
    • Scout 1: “I want to send you a message” (SYN).
    • Scout 2: “I acknowledge your request to send me a message” (SYN + ACK).
    • Scout 1: “I acknowledge your acknowledgement. Here’s my message: [say message]” (ACK).
    • Scout 2: “I have received your message, end transmission.”
  4. Scouts switch roles and practice sending short messages.
  5. Reflect on what was challenging about the activity. Reinforce the concept of the three-way handshake as a way for computers to safely communicate. Talk about why protocols, like the handshake, are important for sharing information securely.
Tia Kennard