#include /* HIDE TEXT IN IMAGE ALGORITHM TO HIDE EXEMPLE : 0101 0010 (pixel value) 0010 0101 (char value) 7 (shift) ALGO : { 0010 0101 >> 7 = 0000 0001 (takes first bit of char) 0101 0010 >> (8 - 7) = 1010 0100 1010 0100 << (8 - 7) = 0101 0010 (erase last bit = last bit's value is 0) 1010 0100 OR 0000 0001 = 1010 0101 -> pixel with first bit of char hidden 0010 0101 >> (8 - 7) = 0100 1010 (shift by 1 = change first bit of char) //then repeat the same with modified char } */ void hide(unsigned char *pxs, unsigned char *msg, unsigned char shift) { //decalage = shif unsigned char a = 0, b = *msg, c = 0; int nb = 8 / (8 - shift), cmp = nb; while(*pxs || *msg) { //example with 21 abd 'H' = 72 //21 = 0001 0101 a = *pxs >> (8 - shift) ; //a = 21 >> 8 - 4 //a = 0000 0001 a <<= (8 - shift) ; //a = 0001 0000 c = b >> (shift) ; //c = 72 >> 4 //c = 0000 0100 a ^= c; //a = 0001 0000 OR 0000 0100 //a = 0001 0100 = 20 *pxs = a; b <<= (8 - shift) ; //b = 0100 1000 << 4 //b = 1000 0000 printf("%d ", c); if (cmp == 1) { ++msg ; a = 0, b = *msg, c = 0; cmp = nb; if(*msg == 0) { break; } } else { --cmp; } ++pxs; } } unsigned char *search(unsigned char *pxs, unsigned char shift, long int pxsLen) { int nb = 8 / (8 - shift) ; unsigned char *msg = (unsigned char*)malloc(nb + 1); unsigned char *msgPtr = msg ; if(!msg) { printf("Error..."); return; } unsigned char a, b = 0, c ; int cmp = nb ; while(*pxs) { a = *pxs << shift ; a >>= shift ; printf("%d, ", a) ; b ^= a ; if(cmp == 1) { *msgPtr = b ; printf("ok"); ++msgPtr ; cmp = nb; b = 0; } else { b <<= (8 - shift) ; --cmp ; } ++pxs; } msg[nb] = 0; return msg ; } int main() { //image's pixels unsigned char pxs[] = {21, 41, 30, 4, 5, 10, 32, 50} ; //message to hide unsigned char msg[] = "Hi" ; //shift unsigned char shift = 4 ; //shift = number of pixel per char //function call hide(pxs, msg, shift); unsigned char *ptr = msg; printf("\n"); for (int i =0;i<8;i++) { printf("%d, ", pxs[i]); } printf("\n"); char *c = search(pxs, shift, 8) ; printf("\nRESULT : %s", c) ; return 0; }

steganography