Theory

R3zk0n · October 2, 2025

Network   Security
Contents

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    Phases

    • Agreement on Security Protocols
    • 802.1X Authentication (if not WPA-PSK) + Association
    • Key Distribution and Verification (Password-based if WPA-PSK)
    • Data Exchange

    WEP (Wired Equivalent Privacy) / TKIP and CCMP - encryption techniques

    • WEP: Open or shared authentication; using RC4 ciphers + CRC32 checksum
    • TKIP: Temporal Key Integrity Protocol
    • CCMP: Counter Mode with Cypher Block Chaining Message Authentication Code Protocol (AES)

    802.1X and EAP (Enterprise/Extensible Authentication Protocol)

    • Resource: https://www.youtube.com/watch?v=bzWdE0Hc-jQ
    • Network Authentication to Wireless Access Point to derive a Pairwise Master Key (PTK).
      • EAP-TLS: Low level authentication protocol before TCP/IP since no IP address is assigned yet.
      • 802.1X Port Control - controlled port only accepots EAPOL frames
        • Supplicant EAPOL-Start –> Login Request –> Login Response to Authenticator Switch (e.g. Cisco Catalyst Switch)
        • Authenticator –> Check Policy Database –> Informs Switch –> Switch enforce policy to Cisco ISE
      • Derive the PMK - Pairwise Master Key

    4-Way Handshake

    • Resource: https://www.youtube.com/watch?v=9M8kVYFhMDw
    • Using the PMK to derive a Pairwise Transient Key (PTK) - which is a data encryption key
    • This occurs after open system authentication and 802.1X EAP association
      1. Access Point sends Anonce
      2. Client generates PTK and sends Snonce + MIC to validate by PTK by AP
      3. GTK (Group Temporal Key) is calculated by AP standalone, sends GTK + MIC to protect the frame
      4. Client OK
    • Inputs to encryption key: PMK + Anonce + Snonce + AP MAC + Client MAC

    How mac80211 Wireless Framework interacts with each other

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