a) if input 1011
= 0 1 1 1
b) if input 0110
= 1 1 0 0
my answer right?
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$\begingroup$ For b, if the input is 0110, the answer should be 0011. $\endgroup$– Geoffroy CouteauDec 19, 2017 at 8:30
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1 Answer
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No, your answers are incorrect by my reading of the description. The leftmost bit can't change, since only the other three bits are rotated. That does make for a pretty terrible s-box, but it's an exercise anyway...
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$\begingroup$ aha im understand you 1011 ===> 1110 0111 ===> 0111 same $\endgroup$– A_CoderDec 16, 2017 at 19:27
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$\begingroup$ 1011: Rotate the rightmost three bits right by one bit. 011 >>> 101. Therefore 1101. 0110: Rotate the rightmost three bits left by one bit: 110 <<< 101. Therefore 0101. $\endgroup$ Dec 17, 2017 at 6:44