38 lines
1.5 KiB
Python
38 lines
1.5 KiB
Python
# @file des_block_demo.py
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# @brief How to use des_block class.
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# @author Laurent Sauvage <laurent.sauvage@telecom-paristech.fr>
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from des_block import *
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KSHIFTS= ( 0, 1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1 )
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if __name__ == "__main__":
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#========================================
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P= des_block("0x0123456789abcdef", 64) # Create a 64-bit wide DES block
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print ("P={} (hex) {} (dec)".format(P, P.value()))
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#========================================
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L0, R0= P.ip() # Initial permutation
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print ("L0= {} Ro={}".format(L0, R0))
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invip_ip_P= L0.concat(R0).ip(-1) # Inverse of Initial permutation
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print ("invip_ip_P=", invip_ip_P)
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print ("diff=", P.xor(invip_ip_P))
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#========================================
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KEY= des_block("0xfedcba9876543210", 64) # Create a 64-bit wide DES block
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print ("Master KEY=", KEY)
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pc1_KEY= KEY.pc1() # @note Inverse of pc1() = pc1(-1)
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C0= pc1_KEY.subblock( 0, 28)
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D0= pc1_KEY.subblock(28, 56)
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C1= C0.ls(KSHIFTS[1]) # @note Left shift of n : ls(n)
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# Inverse of left shift : rs(n)
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# KSHIFTS[r] = number of shifts for round r
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D1= D0.ls(KSHIFTS[1])
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K1= C1.concat(D1).pc2() # @note Inverse of pc2() = pc2(-1)
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print ("Round Key K1=", K1)
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#========================================
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inS= R0.e().xor(K1)
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outS= des_block()
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for i in range(0, 8): # for Sbox from 0 to 7
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outS= outS.concat( inS.subblock(6*i, 6*i+6).s(i) )
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R1= outS.p().xor(L0) # @note Inverse of p() : p(-1)
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print ("R1=", R1)
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