17.6 TKIP

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The Temporal Key Integrity Protocol (TKIP) is a more recent security feature offered by various vendors to correct WEP's weaknesses. TKIP was developed by some of the same researchers who found the vulnerabilities in the RC4 implementation.

TKIP still uses RC4 as the encryption algorithm, but it removes the weak key problem and forces a new key to be generated every 10,000 packets or 10 KB, depending on the source. In addition, it hashes the initialization vector values, which are sent as plain text in the current release of WEP. This means the IVs are now encrypted and are not as easy to sniff out of the air. Since the first three characters of the secret key are based on the three-character IV, the hashing of this value is a must. Without protecting the IV from casual sniffing attacks, a hacker can turn a 64-bit key (based on 8 characters x 8 bytes in a bit) into a 40-bit key (based on 8-3 characters x 8 bytes in a bit).

Even with this extra security, TKIP is designed like the current version of WEP. The similarity allows TKIP to be backward compatible with most hardware devices. Consumers merely have to update their firmware or software in order to bring their WLANs up to par.

While this new security measure is important, it is only temporary; TKIP is like a Band-aid to patch the hemorrhaging WEP security. TKIP still operates under the condition that an attacker only has to crack one password in order to gain access to the WLAN ”one of the major factors that caused the current release of WEP to be crackable. If WEP included a multifaceted security scheme using stronger encryption and/or multiple means of authentication, an attacker would have to attack the WLAN from several points, thus making WEP cracking much more difficult.

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Security Warrior
Security Warrior
ISBN: 0596005458
EAN: 2147483647
Year: 2004
Pages: 211

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