Question

b) The final design of the Feistel Cipher is given in Figure 2. Show appropriate mathematical calculations and reasoning to derive, L6 = L1 and R6 = R1. Explain how is it different from the previous designs? Round 2 Swapper Mixer Round 1 Swapper Mixer L? R? f(R?, K?) K? + L? R? f (R?, K?) ----K? + L? R? Encryption Round 1 Swapper Mixer Figure 2: Figure for question no. 3(b) Round 2 Swapper Mixer + L? R? + f(R?, K?) K? L? R? f(L?, K?) K? L? R? Decryption

          b) The final design of the Feistel Cipher is given in Figure 2. Show appropriate
mathematical calculations and reasoning to derive, L6 = L1 and R6 = R1. Explain how
is it different from the previous designs?
Round 2
Swapper
Mixer
Round 1
Swapper
Mixer
L?
R?
f(R?, K?)
K?
+
L?
R?
f (R?, K?)
----K?
+
L?
R?
Encryption
Round 1
Swapper
Mixer
Figure 2: Figure for question no. 3(b)
Round 2
Swapper
Mixer
+
L?
R?
+
f(R?, K?)
K?
L?
R?
f(L?, K?)
K?
L?
R?
Decryption

b) The final design of the Feistel Cipher is given in Figure 2. Show appropriate
mathematical calculations and reasoning to derive, L6 = L1 and R6 = R1. Explain how
is it different from the previous designs?
Round 2
Swapper
Mixer
Round 1
Swapper
Mixer
L?
R?
f(R?, K?)
K?
+
L?
R?
f (R?, K?)
—-K?
+
L?
R?
Encryption
Round 1
Swapper
Mixer
Figure 2: Figure for question no. 3(b)
Round 2
Swapper
Mixer
+
L?
R?
+
f(R?, K?)
K?
L?
R?
f(L?, K?)
K?
L?
R?
Decryption

Added by Susan W.

Computer Science and Information Technology

Trishna Knowledge Systems 2018 Edition

Instant Answer

Solved by Expert Crystal Wang

Step 1

- Each round uses a subkey (K1, K2, etc.) and a function f to transform the data. Show more…

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The final design of the Feistel Cipher is given in Figure 2. Show appropriate mathematical calculations and reasoning to derive L6 = L1 and R6 = R1. Explain how it is different from the previous designs. L1 R1 L6 R6 + Mixer f(R3,K) ...K Round 2 Swapper Ls Rs Mixer f(R,K) Round 1 L2 R2 + Mixer f(R2,K) Mixer f(L4,K) ..K Round 2 Round 1 A Swapper Swapper L3 R3 L4 R4 Encryption Decryption Figure 2: Figure for question no. 3(b)