Analiza sigurnosnih protokola WEP i WPA1 u bežičnim lokalnim mrežama

undergraduate thesis

• Title (english): Analysis of WEP and WPA1 security protocols in wireless local area networks
• Author: Tomislav Stanić
• Mentor: Željko Ilić (mentor)
• Committee member: Željko Ilić (predsjednik povjerenstva)
• Committee member: Nenad Markuš (član povjerenstva)
• Committee member: Matija Šulc (član povjerenstva)
• Granter: University of Zagreb; Faculty of Electrical Engineering and Computing; Zagreb
• Defense date and country: 2016-07-11, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Computing
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Electrical Engineering

Abstract

Ubrzanim razvojom bežičnih komunikacija pojavila se potreba za snažnim sigurnosnim mehanizmima koji bi štitili komunikaciju i promet od pogrešaka u prijenosu te nedopuštenog pristupa mreži ili napada na istu. Kao odgovor na sigurnosne standarde u ožičenim mrežama, u sklopu standarda 802.11 ratificiranog 1997. godine predstavljan je protokol WEP (eng. Wired Equivalent Privacy). Protokol WEP za enkripciju oslanjao se na algoritam RC4, a za očuvanje integriteta poruke na CRC provjeru (eng. Cyclic Redundancy Check). Iako se u to vrijeme činilo da bi protokol WEP mogao pružiti iole kvalitetnu zaštitu, u razdoblju od nekoliko godina kriptoanalitičari su pokazali slabosti WEP-a: kratki inicijalizacijski vektor, nesigurna provjera integriteta, korištenje zajedničkog ključa te nepostojanje mehanizma za upravljanje i zamjenu ključeva. To je dovelo do eksploatacije navedenih mana te pojavljivanja raznih napada (napadi FMS, KoreK i sl.) koji su na kraju doveli i do potrebe za novim rješenjima u sigurnosti bežičnih mreža. Kao odgovor tome, Wi-Fi savez izdaje 2003. godine novi sigurnosni protokol - WPA (eng. Wi-Fi Protected Access) i time uspijeva ispraviti brojne sigurnosne propuste prethodnog standarda. Vijeće IEEE je korisnicima preporučilo prelazak na WPA, koji se za enkripciju oslanja na novi protokol za dinamičku raspodjelu ključeva – TKIP (eng. Temporal Key Integrity Protocol). Protokol TKIP uvodi nove sigurnosne mehanizme poput koda za zaštitu integriteta poruke MIC (eng. Message Integrity Code), nove metode određivanje slijednog broja inicijalizacijskog vektora (u svrhu sprječavanja replay napada), novi način konstrukcije ključa za svaki paket (eng. key mixing function) te mehanizam izmjene ključeva (eng. rekeying mechanism). Što se tiče procesa autentifikacije, postoje dva operacijska moda: WPA-Personal i WPA-Enterprise. WPA-Personal namijenjen je domovima i malim uredima, a temelji se na unaprijed dodijeljenom ključu. WPA-Enterprise komercijalna je verzija WPA standarda, a temelji se na standardu 802.1X te EAP autentificikacijskim metodama.
U zadnjem poglavlju ovog rada opisani su izvršeni napadi na mreže zaštićene protokolima WEP i WPA.

Abstract (english)

With rapid evolution of wireless communication, a need for strong security mechanisms for protection from transfer errors and unauthorized network access and attacks emerges. As a response to security standards in wired networks, as a part of 802.11 standard, ratified in 1997, WEP protocol (Wired Equivalent Privacy) was introduced. For encryption WEP used the RC4 algorithm, and for integrity preservation a CRC (Cyclic Redundancy Check) was used. Although at the time it seemed that WEP could provide somewhat of a quality protection, in the next few years cryptoanalists showed WEP weakenesses: short initialization vector, unsafe integrity check, common key usage and lack of key management mechanisms. That lead to exploatation of these weaknesses and emergence of number of attacks on WEP protection (FMS attack, KoreK attack etc.). As a response, Wi-Fi Alliance introduces new security protocol - WPA (Wi-Fi Protected Access) and manages to correct most of security flaws of the earlier standard. Soon IEEE recommended a fast switch to WPA, which used new dynamic key management protocol - TKIP (Temporal Key Integrity Protocol) for encryption. Temporal key integrity protocol introduces new security mechanisms like Message Integrity Code MIC, new methods for initialization vector sequencing (against replay attacks), key mixing function for generating per-packet keys and rekeying mechanism. In terms of authentication process, there are two operation modes: WPA-Personal and WPA-Enterprise. WPA-Personal is meant for households and small business and its authentication is based on Personal Shared Key (PSK). WPA-Enterprise is a commercial version of WPA standard, based on 802.1X standard and EAP authentication methods.
In last paragraph of this thesis, practical attacks on WEP and WPA protected networks are described.

• Keywords: sigurnost; protokol; WEP; WPA; TKIP; CRC; RC4; enkripcija; autentifikacija
• Keywords (english): security; protocol; WEP; WPA; TKIP; CRC; RC4; encryption; authentication
• Language: croatian
• URN:NBN: urn:nbn:hr:168:248350
• Study programme: Title: Computing; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka računarstva (sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka računarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Closed access
• Created on: 2018-02-06 12:06:18