Lecture 8 - wireless Part 3

Lecture 8 - wireless Part 3 - Understanding and Attacking...

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Duplication of this material is expressly prohibited VIII-1 http://www.foundstone.com Ultimate Hacking Wireless Understanding and Attacking WEP www.foundstone.com Copyright © 2010 McAfee, Inc. Understanding and Attacking WEP 8-2 Overview Understanding WEP Encryption Attacking WEP www.foundstone.com Copyright © 2010 McAfee, Inc. Understanding and Attacking WEP 8-3 Understanding WEP Encryption History Of WEP www.foundstone.com Copyright © 2010 McAfee, Inc. Understanding and Attacking WEP 8-4 Understanding WEP Encryption WEP h No longer considered a viable method of securing 802.11 frames h Protects information transmitted via the wireless network by encrypting the data within the 802.11 frame h The client uses the initialization vector (IV) stored within the frame header and the WEP key to decrypt the data www.foundstone.com Copyright © 2010 McAfee, Inc. Understanding and Attacking WEP 8-5 WEP Encryption Process The CRC-32 ICV h A 4 byte CRC-32 Integrity Check Value (ICV) is computed for the data payload of the packet and appended to it The UNIQUE seed h The shared secret “key” (k) is static h A 24-bit Initialization Vector (IV) is concatenated with the key (k) to form a “unique” seed Plaintext Message (M) ICV [s(M)] Shared Key ( k ) IV www.foundstone.com Copyright © 2010 McAfee, Inc. Understanding and Attacking WEP 8-6 WEP Encryption Process The Keystream h This seed is input into the RC4 stream cipher, which outputs a “keystream” of arbitrary length
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This note was uploaded on 11/02/2010 for the course CS 393 taught by Professor Staff during the Spring '08 term at NYU Poly.

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Lecture 8 - wireless Part 3 - Understanding and Attacking...

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