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Programa:         Unidad6Ejercicio20.cpp
Descripción:      Esteganografía (incluye un texto en un BMP).
#include <iostream>
#include <fstream>
#include <cstring>
#include <cmath>
using namespace std;

struct cabeceraBMP {
        char Signature[2];              /* Signatura = "BM"             */
        unsigned int FileSize;          /* Tamaño Fichero               */
        unsigned int Reserved;          /* Reservado                    */
        unsigned int DataOffset;        /* Desplazamiento de los datos  */

struct propiedadesBMP {
        unsigned int size;               /* Header size in bytes      */
        int width, height;               /* Width and height of image */
        unsigned short int planes;       /* Number of colour planes   */
        unsigned short int bits;         /* Bits per pixel            */
        unsigned int compression;        /* Compression type          */
        unsigned int imagesize;          /* Image size in bytes       */
        int xresolution, yresolution;    /* Pixels per meter          */
        unsigned int ncolours;           /* Number of colours         */
        unsigned int importantcolours;   /* Important colours         */

struct pixel {
        unsigned char byteR, byteG, byteB;

void leeCabecera(ifstream &f, cabeceraBMP &c);
void leePropiedades(ifstream &f, propiedadesBMP &p);
void leeImagen(ifstream &f, char *img, unsigned int tam);
void escribeCabecera(ofstream &f, cabeceraBMP &c);
void escribePropiedades(ofstream &f, propiedadesBMP &p);
void escribeImagen(ofstream &f, char *img, unsigned int tam);
void camufla(char *img, char *cad);
int bit(char c,int pos);

int main() {
        cabeceraBMP cBMP;
        propiedadesBMP pBMP;
        char *imagen;
        unsigned int t;
        char nombreOri[80], nombreDes[80], cad[80];

        cout << "Introduzca el nombre del fichero origen ";
        cin >> nombreOri;
        cout << endl << "Introduzca el nombre del fichero destino ";
        cin >> nombreDes;

        ifstream fe(nombreOri, ios::in | ios::binary);
        ofstream fs(nombreDes, ios::out | ios::binary);

        if(fe.is_open() && fs.is_open())
                imagen = new char[pBMP.imagesize];

                cout << "Introduzca una cadena ";
                cin >> cad;
                camufla(imagen, cad);


                cout << "Error: El fichero no existe ";

void leeCabecera(ifstream &f, cabeceraBMP &c)
{<char*>(&c.Signature[0]), sizeof(c.Signature[0]));<char*>(&c.Signature[1]), sizeof(c.Signature[1]));<char*>(&c.FileSize), sizeof(c.FileSize));<char*>(&c.Reserved), sizeof(c.Reserved));<char*>(&c.DataOffset), sizeof(c.DataOffset));

void leePropiedades(ifstream &f, propiedadesBMP &p)
{<char*>(&p.size), sizeof(p.size));<char*>(&p.width), sizeof(p.width));<char*>(&p.height), sizeof(p.height));<char*>(&p.planes), sizeof(p.planes));<char*>(&p.bits), sizeof(p.bits));<char*>(&p.compression), sizeof(p.compression));<char*>(&p.imagesize), sizeof(p.imagesize));<char*>(&p.xresolution), sizeof(p.xresolution));<char*>(&p.yresolution), sizeof(p.yresolution));<char*>(&p.ncolours), sizeof(p.ncolours));<char*>(&p.importantcolours), sizeof(p.importantcolours));
        if(p.imagesize == 0) // La imagen esta comprimida
                p.imagesize = p.width * p.height * p.bits / 8;

void leeImagen(ifstream &f, char *img, unsigned int tam)
        for(unsigned int i = 0; i < tam; i++)
      <char*>(img + i), sizeof(*img));

void escribeCabecera(ofstream &f, cabeceraBMP &c)
        f.write(reinterpret_cast<char*>(&c.Signature[0]), sizeof(c.Signature[0]));
        f.write(reinterpret_cast<char*>(&c.Signature[1]), sizeof(c.Signature[1]));
        f.write(reinterpret_cast<char*>(&c.FileSize), sizeof(c.FileSize));
        f.write(reinterpret_cast<char*>(&c.Reserved), sizeof(c.Reserved));
        f.write(reinterpret_cast<char*>(&c.DataOffset), sizeof(c.DataOffset));

void escribePropiedades(ofstream &f, propiedadesBMP &p)
        f.write(reinterpret_cast<char*>(&p.size), sizeof(p.size));
        f.write(reinterpret_cast<char*>(&p.width), sizeof(p.width));
        f.write(reinterpret_cast<char*>(&p.height), sizeof(p.height));
        f.write(reinterpret_cast<char*>(&p.planes), sizeof(p.planes));
        f.write(reinterpret_cast<char*>(&p.bits), sizeof(p.bits));
        f.write(reinterpret_cast<char*>(&p.compression), sizeof(p.compression));
        f.write(reinterpret_cast<char*>(&p.imagesize), sizeof(p.imagesize));
        f.write(reinterpret_cast<char*>(&p.xresolution), sizeof(p.xresolution));
        f.write(reinterpret_cast<char*>(&p.yresolution), sizeof(p.yresolution));
        f.write(reinterpret_cast<char*>(&p.ncolours), sizeof(p.ncolours));
        f.write(reinterpret_cast<char*>(&p.importantcolours), sizeof(p.importantcolours));

void escribeImagen(ofstream &f, char *img, unsigned int tam)
        for(unsigned int i = 0; i < tam; i++)
                f.write(reinterpret_cast<char*>(img + i), sizeof(*img));

int bit(char c,int pos)
    int res;
    pos = pow(2, pos);
    res = c & pos ? 1 : 0;
    return res;

void camufla(char *img, char *cad)

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