Description: <div style="text-align: justify;">This is a part of TKIP Primer video series. The last few videos explain about the problems in WEP and how WPA-TKIP tries to mitigate most of them, without replacing the hardware. This video explains more about how the TKIP packet are formed from the clean text packet and the TSC(TKIP Sequence Counter) . The TSC is constructed from the first and second bytes from the original WEP IV and the 4 bytes provided in the extended IV. TKIP extends the length of a WEP encrypted MPDU by 12 bytes—4 bytes for the extended IV information and 8 bytes for the MIC. The temporal key, transmitter address, and TSC are combined in a two-phase key mixing function to generate a per packet key to be used to seed the WEP engine for encryption. The per packet key is 128 bits long and is split into a 104-bit RC4 key and a 24-bit IV for presentation to the WEP engine. The MIC is calculated over the source and destination MAC addresses and the MSDU plaintext after being seeded by the MIC key and the TSC. By computing the MIC over the source and destination addresses, the packet data is keyed to the sender and receiver preventing attacks based on packet forgery. <br><br><br></div><br><style type="text/css">body { background: #FFF; } </style>
Tags: basics ,
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