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 insufficient 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 Access<TM> (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_access.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 compro-
       mise on strong security and possibility to use existing hardware. It still uses RC4 for the encryption like WEP, but  with  per-packet  RC4
       keys. In addition, it implements replay protection, keyed packet authentication mechanism (Michael MIC).

       Keys  can  be managed using two different mechanisms. WPA can either use an external authentication server (e.g., RADIUS) 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", respec-
       tively. 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 encryption 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  mes-
       sages in initial key handshake, pre-authentication, and PMKSA caching).

SEE ALSO

       wpa_supplicant(8)

LEGAL

       wpa_supplicant is copyright (c) 2003-2007, Jouni Malinen <j@w1.fi> and contributors.  All Rights Reserved.

       This program is dual-licensed under both the GPL version 2 and BSD license. Either license may be used at your option.

								 07 September 2010						 WPA_BACKGROUND(8)