Answer Happy

This problem provides a numerical example of encryption using a
one-round version of DES. Let us start with the same bit pattern
for the key K and the plaintext, namely:
PLAINTEXT: 0 1 2 3 4 5 6 7 8 9 A B C D E F
KEY : 0 1 2 3 4 5 6 7 8 9 A B C D E F
a. Derive K1, the first-round subkey. [3 marks]
b. Derive L0, R0. [3 marks]
c. Expand R0 to get E[R0], where E[.] is the expansion function of
Table S.1. [3 marks]
d. Calculate A = E[R0] XOR K1. [1 marks]
e. Group the 48-bit result of (d) into sets of 6 bits and evaluate
the corresponding Sbox
substitutions. [3 marks]
f. Concatenate the results of (e) to get a 32-bit result, B. [2
marks]
g. Apply the permutation to get P(B). [3 marks]
h. Calculate R1 = P(B) XOR L0 . [1 marks]
i. Write down the ciphertext. [1 marks]