Manual: wpa_background

WPA_BACKGROUND(8)											   WPA_BACKGROUND(8)

NAME
       wpa_background - Background information on Wi-Fi Protected Access and IEEE 802.11i

WPA
       The  original  security mechanism of IEEE 802.11 standard was not designed to be strong and has proven to be insuffi‐
       cient for most networks that require some kind of security. Task group I (Security)  of	IEEE  802.11  working  group
       (http://www.ieee802.org/11/)  has  worked to address the flaws of the base standard and has in practice completed its
       work in May 2004. The IEEE 802.11i amendment to the IEEE 802.11 standard was approved in June 2004 and  published  in
       July 2004.

       Wi-Fi  Alliance	(http://www.wi-fi.org/) used a draft version of the IEEE 802.11i work (draft 3.0) to define a subset
       of the security enhancements that can be implemented with existing wlan hardware. This is called Wi-Fi Protected	 Ac‐
       cess (WPA). This has now become a mandatory component of interoperability testing and certification done by Wi-Fi
       Alliance.  Wi-Fi	 provides  information	about  WPA  at	its web site (http://www.wi-fi.org/OpenSection/protected_ac‐
       cess.asp).

       IEEE 802.11 standard defined wired equivalent privacy (WEP) algorithm for protecting wireless networks. WEP uses	 RC4
       with  40-bit  keys, 24-bit initialization vector (IV), and CRC32 to protect against packet forgery. All these choices
       have proven to be insufficient: key space is too small against current attacks, RC4 key	scheduling  is	insufficient
       (beginning  of  the  pseudorandom stream should be skipped), IV space is too small and IV reuse makes attacks easier,
       there is no replay protection, and non-keyed authentication does not protect against bit flipping packet data.

       WPA is an intermediate solution for the security issues. It uses Temporal Key Integrity Protocol	 (TKIP)	 to  replace
       WEP.  TKIP is a compromise on strong security and possibility to use existing hardware. It still uses RC4 for the en‐
       cryption like WEP, but with per-packet RC4 keys. In addition, it implements replay protection, keyed packet authenti‐
       cation mechanism (Michael MIC).

       Keys can be managed using two different mechanisms. WPA can either use an external authentication server	 (e.g.,	 RA‐
       DIUS)  and  EAP	just  like  IEEE 802.1X is using or pre-shared keys without need for additional servers. Wi-Fi calls
       these "WPA-Enterprise" and "WPA-Personal", respectively. Both mechanisms will generate a master session key  for	 the
       Authenticator (AP) and Supplicant (client station).

       WPA  implements	a new key handshake (4-Way Handshake and Group Key Handshake) for generating and exchanging data en‐
       cryption keys between the Authenticator and Supplicant. This handshake is also used to verify that both Authenticator
       and Supplicant know the master session key. These handshakes are identical regardless of the selected key  management
       mechanism (only the method for generating master session key changes).

IEEE 802.11I / WPA2
       The design for parts of IEEE 802.11i that were not included in WPA has finished (May 2004) and this amendment to IEEE
       802.11 was approved in June 2004. Wi-Fi Alliance is using the final IEEE 802.11i as a new version of WPA called WPA2.
       This includes, e.g., support for more robust encryption algorithm (CCMP: AES in Counter mode with CBC-MAC) to replace
       TKIP  and  optimizations	 for  handoff  (reduced number of messages in initial key handshake, pre-authentication, and
       PMKSA caching).

SEE ALSO
       wpa_supplicant(8)

LEGAL
       wpa_supplicant is copyright (c) 2003-2022, Jouni Malinen  and contributors.  All Rights Reserved.

       This program is licensed under the BSD license (the one with advertisement clause removed).

						       07 August 2019					   WPA_BACKGROUND(8)