Question

Hands-on Exercise #6: DES (Chapter 4) 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: 0123456789ABCDEF Binary notation: 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111 a) Derive $K_1$, the first-round subkey. b) Derive $L_0$, $R_0$. c) Expand $R_0$ to get $E[R_0]$, where $E[\cdot]$ is the expansion function of Table S.1. d) Calculate $A = E[R_0] \text{ XOR } K_1$. e) Group the 48-bit result of (d) into sets of 6 bits and evaluate 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 $R_1 = P(B) \text{ XOR } L_0$. i) Write down the ciphertext.

          Hands-on Exercise #6: DES (Chapter 4)
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: 0123456789ABCDEF
Binary notation:
0000 0001 0010 0011 0100 0101 0110 0111
1000 1001 1010 1011 1100 1101 1110 1111
a) Derive $K_1$, the first-round subkey.
b) Derive $L_0$, $R_0$.
c) Expand $R_0$ to get $E[R_0]$, where $E[\cdot]$ is the expansion function of Table S.1.
d) Calculate $A = E[R_0] \text{ XOR } K_1$.
e) Group the 48-bit result of (d) into sets of 6 bits and evaluate 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 $R_1 = P(B) \text{ XOR } L_0$.
i) Write down the ciphertext.

Hands-on Exercise #6: DES (Chapter 4)
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: 0123456789ABCDEF
Binary notation:
0000 0001 0010 0011 0100 0101 0110 0111
1000 1001 1010 1011 1100 1101 1110 1111
a) Derive K1, the first-round subkey.
b) Derive L0, R0.
c) Expand R0 to get E[R0], where E[·] is the expansion function of Table S.1.
d) Calculate A = E[R0] XOR K1.
e) Group the 48-bit result of (d) into sets of 6 bits and evaluate 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 = P(B) XOR L0.
i) Write down the ciphertext.

Added by Vincent K.

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