87 lines
2.5 KiB
C++
87 lines
2.5 KiB
C++
/*
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* decode.cpp
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*
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* The files in this directory and elsewhere which refer to this LICENCE
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* file are part of Jastegal (Just Another Steganography algorithm)
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*
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* Copyright (C) 2009 BlackLight
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*
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* Jastegal is free software; you can redistribute it and/or modify it under
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* the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 3 or (at your option) any later
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* version.
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*
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* Jastegal is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with Jastegal; if not, write to the Free Software Foundation, Inc.,
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* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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*
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* As a special exception, if other files instantiate templates or use
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* macros or inline functions from these files, or you compile these
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* files and link them with other works to produce a work based on these
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* files, these files do not by themselves cause the resulting work to be
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* covered by the GNU General Public License. However the source code for
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* these files must still be made available in accordance with section (3)
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* of the GNU General Public License.
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*
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* This exception does not invalidate any other reasons why a work based on
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* this file might be covered by the GNU General Public License.
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*/
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#include <CImg.h>
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#include <string>
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#include "jastegal.h"
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using namespace std;
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using namespace cimg_library;
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string steganoDecode (string inImg) {
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CImg<u8> img(inImg.c_str());
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rgb header[8];
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string content;
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unsigned int uLen, size = 0;
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for (unsigned int i=0; i < 8; i++) {
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header[i].r = img[3*i];
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header[i].g = img[3*i + 1];
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header[i].b = img[3*i + 2];
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}
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for (unsigned int i=0; i < 8; i++) {
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size |= ((header[i].r & 0x3) << (i*4));
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size |= ((header[i].b & 0x3) << ((i*4)+2));
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}
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for (unsigned int i=6*sizeof(unsigned int); i < 6*(size + sizeof(unsigned int)); i+=6) {
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rgb couple[2];
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u8 buf = 0;
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for (unsigned int j=0; j<2; j++) {
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couple[j].r = img[i + 3*j];
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couple[j].g = img[i + 3*j + 1];
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couple[j].b = img[i + 3*j + 2];
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}
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buf =
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( ((couple[0].r & 0x3) << 6) |
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((couple[0].b & 0x3) << 4) |
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((couple[1].r & 0x3) << 2) |
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((couple[1].b & 0x3)) );
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content += buf;
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}
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char *uncompressed = zUncompress((char*) content.c_str(), size, uLen);
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if (!uncompressed)
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return string("");
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return string(uncompressed);
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}
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