1. This problem provides a numerical example of encryption using a one-round version of DES. We start with the same bit pattern for the key K and the plaintext, namely:

Hexadecimal notation: 8 9 A B D C F E 0 1 2 3 4 5 6 7

Binary notation: 1000 1001 1010 1011 1101 1100 11111110

0000 0001 0010 0011 0100 0101 0110 0111

a. Derive K1 , the first-round subkey.

i. show the result after permutation 1.

ii. show the result after leftshift.

iii. Show the result of K₁ after the permutation 2.

b. Derive L0, R0. (L0, R0 are obtained after initial permutation)

c. Expand R0 to get E[R0], where E[] is the expansion function.

d. Calculate A=E[R0]K1.

e. Group the 48-bit result of (d) into eight sets of 6 bits and conduct the corresponding S-box substitutions.

f. Concatenate the results of (e) to get a 32-bit result, B.

g. Apply the permutation to get P(B).

h. Calculate R1=PBL0.

i. Write down the ciphertext. (Note: we have a 32-bit swap operation and the inverse initial permutation steps at last)