For Crypto system Reduced DES (R-DES) Protocol, write code in python, C#, C, C++, or Java to develop the following functions:

- Key Scheduler - input is 12-bit string, output are three 4-bit round keys

- R-DES - input x = stream of bytes, k = 12-bit key string, flag = 0 for encryption and 1 for decryption.

Outline:

Plaintext and Ciphertext block size = 8-bit strings

Keyspace: key = {12-bit strings b₁,b₂,b₃,..b₁₀,b₁₁,b₁₂}.

Key Scheduling algorithm will generate the following 4-bit strings for the three rounds of the system:

K¹= (b₁,b₂,b₃,b₄) XOR (b₅,b₆,b₇,b₈)

K²=(b₅,b₆,b₇,b₈) XOR (b₉,b₁₀,b₁₁,b₁₂)

K³=(b₉,b₁₀,b₁₁,b₁₂) XOR (b₁,b₂,b₃,b₄)

Encryption Algorithm

Input: L₀R₀ where L₀ and R₀ are the two nibbles of the plain byte.

For round 1=1:3 {L_i = R_i-1; R_i=Kⁱ XOR R_i-1 XOR L_i-1}

Output: R₃L₃

Decryption Algorithm is the same as Encryption Algorithm but with reverse key rounds.