granicus.if.org Git - imagemagick/blob - coders/stegano.c

   1 /*
   2 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   3 %                                                                             %
   4 %                                                                             %
   5 %                                                                             %
   6 %              SSSSS  TTTTT  EEEEE   GGGG   AAA   N   N   OOO                 %
   7 %              SS       T    E      G      A   A  NN  N  O   O                %
   8 %               SSS     T    EEE    G  GG  AAAAA  N N N  O   O                %
   9 %                 SS    T    E      G   G  A   A  N  NN  O   O                %
  10 %              SSSSS    T    EEEEE   GGG   A   A  N   N   OOO                 %
  11 %                                                                             %
  12 %                                                                             %
  13 %                       Write A Steganographic Image.                         %
  14 %                                                                             %
  15 %                              Software Design                                %
  16 %                                John Cristy                                  %
  17 %                                 July 1992                                   %
  18 %                                                                             %
  19 %                                                                             %
  20 %  Copyright 1999-2011 ImageMagick Studio LLC, a non-profit organization      %
  21 %  dedicated to making software imaging solutions freely available.           %
  22 %                                                                             %
  23 %  You may not use this file except in compliance with the License.  You may  %
  24 %  obtain a copy of the License at                                            %
  25 %                                                                             %
  26 %    http://www.imagemagick.org/script/license.php                            %
  27 %                                                                             %
  28 %  Unless required by applicable law or agreed to in writing, software        %
  29 %  distributed under the License is distributed on an "AS IS" BASIS,          %
  30 %  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.   %
  31 %  See the License for the specific language governing permissions and        %
  32 %  limitations under the License.                                             %
  33 %                                                                             %
  34 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  35 %
  36 %
  37 */
  38 \f
  39 /*
  40   Include declarations.
  41 */
  42 #include "magick/studio.h"
  43 #include "magick/blob.h"
  44 #include "magick/blob-private.h"
  45 #include "magick/cache.h"
  46 #include "magick/colormap.h"
  47 #include "magick/constitute.h"
  48 #include "magick/exception.h"
  49 #include "magick/exception-private.h"
  50 #include "magick/image.h"
  51 #include "magick/image-private.h"
  52 #include "magick/list.h"
  53 #include "magick/magick.h"
  54 #include "magick/memory_.h"
  55 #include "magick/monitor.h"
  56 #include "magick/monitor-private.h"
  57 #include "magick/quantum-private.h"
  58 #include "magick/static.h"
  59 #include "magick/string_.h"
  60 #include "magick/module.h"
  61 \f
  62 /*
  63 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  64 %                                                                             %
  65 %                                                                             %
  66 %                                                                             %
  67 %   R e a d S T E G A N O I m a g e                                           %
  68 %                                                                             %
  69 %                                                                             %
  70 %                                                                             %
  71 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  72 %
  73 %  ReadSTEGANOImage() reads a steganographic image hidden within another
  74 %  image type.  It allocates the memory necessary for the new Image structure
  75 %  and returns a pointer to the new image.
  76 %
  77 %  The format of the ReadSTEGANOImage method is:
  78 %
  79 %      Image *ReadSTEGANOImage(const ImageInfo *image_info,
  80 %        ExceptionInfo *exception)
  81 %
  82 %  A description of each parameter follows:
  83 %
  84 %    o image_info: the image info.
  85 %
  86 %    o exception: return any errors or warnings in this structure.
  87 %
  88 */
  89
  90 static inline size_t MagickMin(const size_t x,
  91   const size_t y)
  92 {
  93   if (x < y)
  94     return(x);
  95   return(y);
  96 }
  97
  98 static Image *ReadSTEGANOImage(const ImageInfo *image_info,
  99   ExceptionInfo *exception)
 100 {
 101 #define GetBit(alpha,i) MagickMin((((size_t) (alpha) >> (size_t) \
 102   (i)) & 0x01),16)
 103 #define SetBit(alpha,i,set) (alpha)=(IndexPacket) ((set) != 0 ? \
 104   (size_t) (alpha) | (one << (size_t) (i)) : (size_t) \
 105   (alpha) & ~(one << (size_t) (i)))
 106
 107   Image
 108     *image,
 109     *watermark;
 110
 111   ImageInfo
 112     *read_info;
 113
 114   int
 115     c;
 116
 117   MagickBooleanType
 118     status;
 119
 120   PixelPacket
 121     pixel;
 122
 123   register IndexPacket
 124     *indexes;
 125
 126   register PixelPacket
 127     *q;
 128
 129   register ssize_t
 130     x;
 131
 132   size_t
 133     depth,
 134     one;
 135
 136   ssize_t
 137     i,
 138     j,
 139     k,
 140     y;
 141
 142   /*
 143     Initialize Image structure.
 144   */
 145   assert(image_info != (const ImageInfo *) NULL);
 146   assert(image_info->signature == MagickSignature);
 147   if (image_info->debug != MagickFalse)
 148     (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",
 149       image_info->filename);
 150   assert(exception != (ExceptionInfo *) NULL);
 151   assert(exception->signature == MagickSignature);
 152   one=1;
 153   image=AcquireImage(image_info);
 154   if ((image->columns == 0) || (image->rows == 0))
 155     ThrowReaderException(OptionError,"MustSpecifyImageSize");
 156   read_info=CloneImageInfo(image_info);
 157   SetImageInfoBlob(read_info,(void *) NULL,0);
 158   *read_info->magick='\0';
 159   watermark=ReadImage(read_info,exception);
 160   read_info=DestroyImageInfo(read_info);
 161   if (watermark == (Image *) NULL)
 162     return((Image *) NULL);
 163   watermark->depth=MAGICKCORE_QUANTUM_DEPTH;
 164   if (AcquireImageColormap(image,MaxColormapSize) == MagickFalse)
 165     ThrowReaderException(ResourceLimitError,"MemoryAllocationFailed");
 166   if (image_info->ping != MagickFalse)
 167     {
 168       (void) CloseBlob(image);
 169       return(GetFirstImageInList(image));
 170     }
 171   /*
 172     Get hidden watermark from low-order bits of image.
 173   */
 174   c=0;
 175   i=0;
 176   j=0;
 177   i=(ssize_t) (watermark->depth-1);
 178   depth=watermark->depth;
 179   for (k=image->offset; (i >= 0) && (j < (ssize_t) depth); i--)
 180   {
 181     for (y=0; (y < (ssize_t) image->rows) && (j < (ssize_t) depth); y++)
 182     {
 183       x=0;
 184       for ( ; (x < (ssize_t) image->columns) && (j < (ssize_t) depth); x++)
 185       {
 186         if ((k/(ssize_t) watermark->columns) >= (ssize_t) watermark->rows)
 187           break;
 188         (void) GetOneVirtualPixel(watermark,k % (ssize_t) watermark->columns,
 189           k/(ssize_t) watermark->columns,&pixel,exception);
 190         q=GetAuthenticPixels(image,x,y,1,1,exception);
 191         if (q == (PixelPacket *) NULL)
 192           break;
 193         indexes=GetAuthenticIndexQueue(image);
 194         switch (c)
 195         {
 196           case 0:
 197           {
 198             SetBit(*indexes,i,GetBit(pixel.red,j));
 199             break;
 200           }
 201           case 1:
 202           {
 203             SetBit(*indexes,i,GetBit(pixel.green,j));
 204             break;
 205           }
 206           case 2:
 207           {
 208             SetBit(*indexes,i,GetBit(pixel.blue,j));
 209             break;
 210           }
 211         }
 212         if (SyncAuthenticPixels(image,exception) == MagickFalse)
 213           break;
 214         c++;
 215         if (c == 3)
 216           c=0;
 217         k++;
 218         if (k == (ssize_t) (watermark->columns*watermark->columns))
 219           k=0;
 220         if (k == image->offset)
 221           j++;
 222       }
 223     }
 224     status=SetImageProgress(image,LoadImagesTag,(MagickOffsetType) i,depth);
 225     if (status == MagickFalse)
 226       break;
 227   }
 228   watermark=DestroyImage(watermark);
 229   (void) SyncImage(image);
 230   return(GetFirstImageInList(image));
 231 }
 232 \f
 233 /*
 234 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 235 %                                                                             %
 236 %                                                                             %
 237 %                                                                             %
 238 %   R e g i s t e r S T E G A N O I m a g e                                   %
 239 %                                                                             %
 240 %                                                                             %
 241 %                                                                             %
 242 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 243 %
 244 %  RegisterSTEGANOImage() adds attributes for the STEGANO image format to
 245 %  the list of supported formats.  The attributes include the image format
 246 %  tag, a method to read and/or write the format, whether the format
 247 %  supports the saving of more than one frame to the same file or blob,
 248 %  whether the format supports native in-memory I/O, and a brief
 249 %  description of the format.
 250 %
 251 %  The format of the RegisterSTEGANOImage method is:
 252 %
 253 %      size_t RegisterSTEGANOImage(void)
 254 %
 255 */
 256 ModuleExport size_t RegisterSTEGANOImage(void)
 257 {
 258   MagickInfo
 259     *entry;
 260
 261   entry=SetMagickInfo("STEGANO");
 262   entry->decoder=(DecodeImageHandler *) ReadSTEGANOImage;
 263   entry->format_type=ImplicitFormatType;
 264   entry->description=ConstantString("Steganographic image");
 265   entry->module=ConstantString("STEGANO");
 266   (void) RegisterMagickInfo(entry);
 267   return(MagickImageCoderSignature);
 268 }
 269 \f
 270 /*
 271 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 272 %                                                                             %
 273 %                                                                             %
 274 %                                                                             %
 275 %   U n r e g i s t e r S T E G A N O I m a g e                               %
 276 %                                                                             %
 277 %                                                                             %
 278 %                                                                             %
 279 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 280 %
 281 %  UnregisterSTEGANOImage() removes format registrations made by the
 282 %  STEGANO module from the list of supported formats.
 283 %
 284 %  The format of the UnregisterSTEGANOImage method is:
 285 %
 286 %      UnregisterSTEGANOImage(void)
 287 %
 288 */
 289 ModuleExport void UnregisterSTEGANOImage(void)
 290 {
 291   (void) UnregisterMagickInfo("STEGANO");
 292 }