The WPA 4-Way Handshake follows this precise functional sequence:

1. Exchanges messages for generating PTK: The Authenticator sends an ANonce (Msg 1), and the Supplicant sends an SNonce (Msg 2). These random values are required to mathematically derive the Pairwise Transient Key (PTK).
2. Proves knowledge of the PMK: The Supplicant includes a Message Integrity Code (MIC) in Msg 2. The Authenticator verifies this MIC to confirm the Supplicant possesses the correct Pairwise Master Key (PMK) before proceeding.
3. Distributes an encrypted GTK to the client: Once the unicast link is authenticated, the Authenticator sends the Group Transient Key (GTK) to the client in Msg 3, encrypted using the Key Encryption Key (KEK) portion of the PTK.
4. Sets first initialization vector (IV): Upon completion (Msg 4), both sides install the keys and initialize their encryption counters (Packet Numbers or Initialization Vectors) to begin encrypted data transmission.

IEEE Standard 802.11i-2004, Amendment 6: Medium Access Control (MAC) Security Enhancements, Section 8.5.3 "4-Way Handshake", Steps 1-4 (outlining Nonce exchange, MIC verification, and GTK transport).

CWSP-206 Official Study Guide (Certified Wireless Security Professional), Chapter: Secure Roaming and the 4-Way Handshake, Section: "The 4-Way Handshake Process" (Details the Exchange -> Verify -> Install order).

HPE7-A01 Aruba Certified Campus Access Professional Exam Guide, Module: WLAN Security, Topic: WPA3/WPA2 Handshake flows.

Cisco Wireless LAN Security White Paper, Section: WPA2 4-Way Handshake (Confirms GTK is sent in Message 3 and Key Installation is the final step).