#include <stdio.h>

#include <string.h>

#include <stdlib.h>

#define LENGTH 5

#define HALF_LENGTH ((LENGTH % 2 == 0)? (LENGTH / 2) : (LENGTH / 2) + 1)

void print(unsigned char str[], int size)

{

int i;

for(i = 0; i < size - 1; i++)

{

printf ("%02X ", str[i] & 0xFF);

}

printf("\n");

}

void getLeft(unsigned char arr[], unsigned char *left)

{

int i;

for(i = 0; i < LENGTH/2; i++)

{

*left++ = arr[i];

}

*left = '\0';

}

void getRight(unsigned char arr[], unsigned char *right)

{

int i;

for(i = LENGTH/2; i < LENGTH - 1; i++)

{

*right++ = arr[i];

}

*right = '\0';

}

void leftCircularShift16Bit(unsigned char arr[])

{

unsigned char mask = 0x80;

unsigned char MSBH = (((arr[0] & mask) == 0) ? 0 : 1);

unsigned char MSBL = (((arr[1] & mask) == 0) ? 0 : 1);

arr[0] = arr[0] << 1;

arr[1] = arr[1] << 1;

arr[0] |= MSBL;

arr[1] |= MSBH;

}

void leftCircularShift32Bit(unsigned char arr[])

{

unsigned char mask = 0x80;

unsigned char MSB0 = (((arr[0] & mask) == 0) ? 0 : 1);

unsigned char MSB1 = (((arr[1] & mask) == 0) ? 0 : 1);

unsigned char MSB2 = (((arr[2] & mask) == 0) ? 0 : 1);

unsigned char MSB3 = (((arr[3] & mask) == 0) ? 0 : 1);

arr[0] = arr[0] << 1;

arr[1] = arr[1] << 1;

arr[2] = arr[2] << 1;

arr[3] = arr[3] << 1;

arr[0] |= MSB1;

arr[1] |= MSB2;

arr[2] |= MSB3;

arr[3] |= MSB0;

}

void rightCircularShift16Bit(unsigned char arr[])

{

unsigned char mask = 0x01;

unsigned char LSBH = (((arr[0] & mask) == 0) ? 0 : 0x80);

unsigned char LSBL = (((arr[1] & mask) == 0) ? 0 : 0x80);

arr[0] = arr[0] >> 1;

arr[1] = arr[1] >> 1;

arr[0] |= LSBL;

arr[1] |= LSBH;

}

void rightCircularShift32Bit(unsigned char arr[])

{

unsigned char mask = 0x01;

unsigned char LSB0 = (((arr[0] & mask) == 0) ? 0 : 0x80);

unsigned char LSB1 = (((arr[1] & mask) == 0) ? 0 : 0x80);

unsigned char LSB2 = (((arr[2] & mask) == 0) ? 0 : 0x80);

unsigned char LSB3 = (((arr[3] & mask) == 0) ? 0 : 0x80);

arr[0] = arr[0] >> 1;

arr[1] = arr[1] >> 1;

arr[2] = arr[2] >> 1;

arr[3] = arr[3] >> 1;

arr[0] |= LSB3;

arr[1] |= LSB0;

arr[2] |= LSB1;

arr[3] |= LSB2;

}

void getPermutationPosition(int position[])

{

int i;

int p[32] = {30,8,2,15,19,20,27,29,31,0,7,14,16,22,5,25,28,12,1,11,26,10,3,13,18,23,24,6,9,17,21,4};

for(i = 0; i < 32; i++)

position[i] = p[i];

}

void permutation(unsigned char original[], unsigned char derived[], int position[], int size)

{

int i;

int j;

unsigned char mask;

unsigned char val;

unsigned char bit;

for(i = 0; i < size/8; i++)

derived[i] = 0;

for(i = 0; i < size; i++)

{

if(i < 8)

val = original[0];

else if(i < 16)

val = original[1];

else if(i < 24)

val = original[2];

else

val = original[3];

mask = 0x01;

mask = mask << (7-(i%8));

bit = (((val & mask) == 0) ? 0 : 1);

if(bit == 1)

{

bit = bit << (7-(position[i] % 8));

if(position[i] < 8)

derived[0] |= bit;

else if(position[i] < 16)

derived[1] |= bit;

else if(position[i] < 24)

derived[2] |= bit;

else

derived[3] |= bit;

}

}

}

void deriveKey(unsigned char iv[], unsigned char key[])

{

int i;

unsigned char liv[HALF_LENGTH];

unsigned char riv[HALF_LENGTH];

unsigned char temp[HALF_LENGTH];

key[0] = 0;

key[1] = 0;

key[2] = 0;

key[3] = 0;

// permutation position

int position[16] = {8,10,5,12,7,15,9,11,13,2,1,0,3,4,6,14};

// split key

getLeft(iv, liv);

getRight(iv, riv);

// left rotate the left key twice

for (i = 0; i < 2; i++)

{

rightCircularShift16Bit(liv);

leftCircularShift16Bit(riv);

}

// liv becomes right part of the derived key

for(i = 0; i < 2; i++)

key[i + 2] = liv[i];

// apply permutation

permutation(riv, temp, position, 16);

// xor temp with liv to form left part of the derived key

for(i = 0; i < HALF_LENGTH - 1; i++)

key[i] = temp[i]^liv[i];

}

void encrypt(unsigned char iv[], unsigned char plain[], unsigned char cipher[])

{

unsigned char key[LENGTH];

unsigned char inter[LENGTH];

int i;

int position[32];

// get permutation position info

getPermutationPosition(position);

// derive key

deriveKey(iv, key);

//Applying RightCircular shift to key

rightCircularShift32Bit(key);

// xor plain text with derived key

for(i = 0; i < LENGTH - 1; i++)

inter[i] = plain[i]^key[i];

// apply permutation

permutation(inter, cipher, position, 32);

// apply left rotation thrice

for(i = 0; i < 3; i++)

leftCircularShift32Bit(cipher);

}

void init (unsigned char arr[], int size)

{

int i;

for(i = 0; i < size; i++)

arr[i] = '\0';

}

void convertHex(unsigned char initkey[], unsigned char iv[])

{

int i;

for(i = 0; i < 8; i++)

if(initkey[i] >= 0x30 && initkey[i] <= 0x39)

if(i%2 == 0)

iv[i/2] |= ((initkey[i] & 0x0F) << 4);

else

iv[i/2] |= (initkey[i] & 0x0F);

else if((initkey[i] >= 0x41 && initkey[i] <= 0x46) || (initkey[i] >= 0x61 && initkey[i] <= 0x66))

if(i%2 == 0)

iv[i/2] |= (((initkey[i] & 0x0F) + 9) << 4);

else

iv[i/2] |= ((initkey[i] & 0x0F) + 9);

}

void main(int argc, char *argv[])

{

unsigned char initkey[9];

int i;

FILE * pFile;

unsigned char iv[LENGTH];

unsigned char ciphertxt[LENGTH];

unsigned char plaintxt[LENGTH];

//Reading the key given at command line and storing it in our initial vector

for(i=0;i<8;i++)

{

initkey[i]=*(argv[1]+i);

}

initkey[8]='\0';

init(iv, LENGTH);

init(ciphertxt, LENGTH);

init(plaintxt, LENGTH);

convertHex(initkey, iv);

// checking to see if the key has been extracted correctly

print(iv, LENGTH);

// Reading plain text from file

pFile = fopen (argv[2] , "r");

if (pFile == NULL) perror ("Error opening file");

else {

if ( fgets (plaintxt , LENGTH , pFile) != NULL )

fclose (pFile);

}

printf("Plain Text : %s\n\n", plaintxt);

encrypt(iv, plaintxt, ciphertxt);

//Applying RightCircular shift

rightCircularShift32Bit(iv);

//Copying Cipher Text to Plain Text

strcpy(plaintxt,ciphertxt);

//updated Plain text is now used for encryption

encrypt(iv, plaintxt, ciphertxt);

//Applying the same set of operations again

rightCircularShift32Bit(iv);

strcpy(plaintxt,ciphertxt);

encrypt(iv, plaintxt, ciphertxt);

// print cipher

printf("Encrypting...\n");

printf("Cipher Text : %s\n\n", ciphertxt);

//Copying Cipher text to output file

pFile = fopen (argv[3],"w");

fputs (ciphertxt,pFile);

fclose (pFile);

}