1. Consider the substitution defined by row 1 of DES S-box S1. Show a block diagram similar to lecture 03 page 7 that corresponds to this substitution.

General n-bit-n-bit Block Substitution (shown with n = 4) 4-Bit Input Encryption and Decryption Tables for Substitution Cipher of the left figure 4 to 16 Decoder 6 8 9 0 2 3 4 5 10 11 12 13 14 15 Plaintext Ciphertext Plaintext 0000 Ciphertext 1110 0100 0000 0001 1110 0011 0100 0010 1101 0001 0011 0100 0101 1000 0001 1100 1010 0110 0111 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 0 1 2 3 4 5 10 11 12 13 14 15 6 7 8 9 16 to 4 Encoder 0010 1111 1011 1000 0011 1010 0110 1100 0101 1001 0000 0111 1000 1001 1111 0111 1101 1001 0110 4-Bit Output 1010 1011 1100 1101 1011 0010 0000 0101 1110 1110 1111 1111 Key length = 2" x n bits General n-bit-n-bit Block Substitution (shown with n = 4) 4-Bit Input Encryption and Decryption Tables for Substitution Cipher of the left figure 4 to 16 Decoder 6 8 9 0 2 3 4 5 10 11 12 13 14 15 Plaintext Ciphertext Plaintext 0000 Ciphertext 1110 0100 0000 0001 1110 0011 0100 0010 1101 0001 0011 0100 0101 1000 0001 1100 1010 0110 0111 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 0 1 2 3 4 5 10 11 12 13 14 15 6 7 8 9 16 to 4 Encoder 0010 1111 1011 1000 0011 1010 0110 1100 0101 1001 0000 0111 1000 1001 1111 0111 1101 1001 0110 4-Bit Output 1010 1011 1100 1101 1011 0010 0000 0101 1110 1110 1111 1111 Key length = 2" x n bits