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#1 2017-09-17 10:47:17

Registered: 2013-04-25
Posts: 5,143

iClass DES representation

Found a nice note in Dismantling_iClass_and_iClass_Elite-ESORICS_2012.pdf
Now I understand the "iclass" vs "standard" comments in the source code.

Remark 3.
The DES implementation used in iClass is non-compliant with the NIST standard in the way of representing keys.
According to the standard, a DESkey is of the form
〈k0...k6 p0,k7...k13 p1,...,k47...k55 p7〉
where k0...k55 are the actual key bits and p0...p7 are parity bits.

Instead, in iClass aDESkeyis of the form

ie: all parity in a byte in the end compared to NIST where the MSB bit in every byte is used.

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