DES Programming Assignment $-$ C$++($no built$-$in functions allowed, everything must be hard$-$coded$).$ Provide the full program including Initial permutation,$16$ rounds of permutation and substitution, and Final permutation. Example is provided in the pictures.

Let the user choose encryption or decryption.

For encryption, let user input the key in Hexadecimal number, the plain text in Hexadecimal number, output the ciphertext $($in hexadecimal numbers$).$

For decryption, let user input the key in Hexadecimal number, the ciphertext $($in hexadecimal numbers$),$ output the decrypted message $($Hexadecimal number$).$An Example of DES Encryption

Here is an example of encryption using the DES. Suppose we encrypt the $($hex$-$

adecimal$)$ plaintext

$0123456789$ABCDEF

using the $($hexadecimal$)$ key

$133457799BBCDFF1.$

The key, in binary, without parity$-$check bits, is

$00010010011010010101101111001001101101111011011111111000.$

Applying IP$,$ we obtain $L_0$ and $R_0($in binary$)$:

$L_0=11001100000000001100110011111111$

$L_1=R_0=11110000101010101111000010101010$

The $16$ rounds of encryption are then performed, as indicated.