.\" This manpage has been automatically generated by docbook2man .\" from a DocBook document.  This tool can be found at:.\" <http://shell.ipoline.com/~elmert/comp/docbook2X/> .\" Please send any bug reports, improvements, comments, patches, .\" etc. to Steve Cheng <steve@ggi-project.org>..TH "WPA_BACKGROUND" "8" "06 May 2006" "" "".SH NAMEwpa_background \- Background information on Wi-Fi Protected Access and IEEE 802.11i.SH "WPA".PPThe original security mechanism of IEEE 802.11 standard wasnot designed to be strong and has proven to be insufficient formost 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 ofthe base standard and has in practice completed its work in May2004. The IEEE 802.11i amendment to the IEEE 802.11 standard wasapproved in June 2004 and published in July 2004..PPWi-Fi Alliance (http://www.wi-fi.org/) used a draft versionof the IEEE 802.11i work (draft 3.0) to define a subset of thesecurity enhancements that can be implemented with existing wlanhardware. This is called Wi-Fi Protected Access<TM> (WPA). Thishas now become a mandatory component of interoperability testingand certification done by Wi-Fi Alliance. Wi-Fi providesinformation about WPA at its web site(http://www.wi-fi.org/OpenSection/protected_access.asp)..PPIEEE 802.11 standard defined wired equivalent privacy (WEP)algorithm for protecting wireless networks. WEP uses RC4 with40-bit keys, 24-bit initialization vector (IV), and CRC32 toprotect against packet forgery. All these choices have proven tobe insufficient: key space is too small against current attacks,RC4 key scheduling is insufficient (beginning of the pseudorandomstream should be skipped), IV space is too small and IV reusemakes attacks easier, there is no replay protection, and non-keyedauthentication does not protect against bit flipping packetdata..PPWPA is an intermediate solution for the security issues. Ituses Temporal Key Integrity Protocol (TKIP) to replace WEP. TKIPis a compromise on strong security and possibility to use existinghardware. It still uses RC4 for the encryption like WEP, but withper-packet RC4 keys. In addition, it implements replay protection,keyed packet authentication mechanism (Michael MIC)..PPKeys can be managed using two different mechanisms. WPA caneither use an external authentication server (e.g., RADIUS) andEAP just like IEEE 802.1X is using or pre-shared keys without needfor additional servers. Wi-Fi calls these "WPA-Enterprise" and"WPA-Personal", respectively. Both mechanisms will generate amaster session key for the Authenticator (AP) and Supplicant(client station)..PPWPA implements a new key handshake (4-Way Handshake andGroup Key Handshake) for generating and exchanging data encryptionkeys between the Authenticator and Supplicant. This handshake isalso used to verify that both Authenticator and Supplicant knowthe master session key. These handshakes are identical regardlessof the selected key management mechanism (only the method forgenerating master session key changes)..SH "IEEE 802.11I / WPA2".PPThe design for parts of IEEE 802.11i that were not includedin WPA has finished (May 2004) and this amendment to IEEE 802.11was approved in June 2004. Wi-Fi Alliance is using the final IEEE802.11i as a new version of WPA called WPA2. This includes, e.g.,support for more robust encryption algorithm (CCMP: AES in Countermode with CBC-MAC) to replace TKIP and optimizations for handoff(reduced number of messages in initial key handshake,pre-authentication, and PMKSA caching)..SH "SEE ALSO".PP\fBwpa_supplicant\fR(8).SH "LEGAL".PPwpa_supplicant is copyright (c) 2003-2005,Jouni Malinen <jkmaline@cc.hut.fi> andcontributors.All Rights Reserved..PPThis program is dual-licensed under both the GPL version 2and BSD license. Either license may be used at your option.