Question

This problem supplies a arithmetical example encryption using a one-round version of DES. We start with the similar bit pattern for the key K and plaintext, namely-

in hexadecimal notation: 0 1 2 3 4 5 6 7 8 9 A B C D E F
in binary notation: 0000 0001 0010 0011 0100 0101 0110 0111
1000 1001 1010 1011 0100 1101 1110 1111

(1) obtain K1, the first-round subkey.

(2) Obtain L0, R0.

(3) Expand R0 to get E[R0], where E[.] is expand function of DES. (Refer to Term Project)

(4) Analyse A = E[R0] K1 .

(5) Group 48-bit result of (4) into sets of 6 bits and evaluate corresponding Sbox substitutions.

(6) Concatenate results of (5) to get a 32-bit result, B.

(7) concern the permutation to get P(B).

(8) Calculate R1 = P(B) L0

(9) Write down ciphertext.