WPA and 802.11i (WPA2)

haveIEEE 802.11i - IEEE 802.11 task group “MAC enhancement for wireless security”.

Wi-Fi Protected Access (WiFi Alliance), WPA, is a subset internal in 802.11i.

Compatible with work developed in 802.11i.

Only supports BSS.

Defined to work in actual equipment.

• Firmware update only.

Pass-phrase constant and shared, but keys are generated per session.

Used in the AP and station.

WPA has two distinct components.

• Authentication, based on 802.1X.

• Ciphering based on TKIP (Temporal Key Integrity Protocol).

WPA

Authentication

802.1X (≠ 802.11x) – defined for wired and wireless sessions, as a transport protocol.

• EAP (Extensible Authentication Protocol) – like a wrapper for the specific authentication traffic.

• Impact of EAP.

  • Authentication does not traverse the AP (STA - server).

  • It is possible to use different authentication methods without changing APs.

Defines also have a Pre-Shared Key (PSK).

• For local networks

Temporal Key Integrity Protocol (TKIP)

Internal solution with better protection, for actual equipment.

• Greater privacy.

  • Uses the same cipher, but is now associated with the MAC and a larger IV.

  • “Key rollover” with temporal validity.

• Greater integrity.

  • Integrity separated key.

802.11i (WPA2)

Better than WPA.

• Also includes TKIP.

• Authentication IBSS (ad-hoc mode)?

• RSN (Robust Security Network) protocol.

  • Authentication and ciphering between APs and stations.

  • Supports new ciphering protocols, resorting to 802.1x and EAP.

  • Supports AES (Advanced Encryption Standard) ciphering.

Problems.

• It does not cipher control and management frames.

  • (Disassociate, output power, etc).

• Requires new hardware.

WPA* Key Exchange (EAP phase 2)

Done during the Association process.

• After Association Request/response frames.

• Uses (QoS) Data Frames.