wpa 802.11

Unanswered Question
Apr 15th, 2008
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hi every body!

one of the components of wpa is mic which stands for message integrity check.if you look at 802.11 frame, one of the field is fcs which is computed over the entire frame,thus assuring the frame integrity.

If fcs can serve the same purpose of data integrity in wlan then why does one need mic?

thanks !

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ciscocsoc Tue, 04/15/2008 - 23:14
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Hi,


MIC is a cryptographic signature whereas FCS is a simpler (and faster to calculate) checksum. The FCS is really there to check that the packet wasn't corrupted by noise. Only after the FCS has been validated does the MIC validation happen. This prevents the security countermeasure threshold from being reached quickly in a noisy environment.


MIC is calculated at the packet level rather than at the frame level so it copes with fragmentation etc.


HTH


Cathy

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