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 1999-2010 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) | (1UL << (size_t) (i)) : (size_t) \
 105   (alpha) & ~(1UL << (size_t) (i)))
 106
 107   Image
 108     *image,
 109     *watermark;
 110
 111   ImageInfo
 112     *read_info;
 113
 114   ssize_t
 115     c,
 116     i,
 117     j,
 118     k,
 119     y;
 120
 121   MagickBooleanType
 122     status;
 123
 124   PixelPacket
 125     pixel;
 126
 127   register IndexPacket
 128     *indexes;
 129
 130   register ssize_t
 131     x;
 132
 133   register PixelPacket
 134     *q;
 135
 136   size_t
 137     depth;
 138
 139   /*
 140     Initialize Image structure.
 141   */
 142   assert(image_info != (const ImageInfo *) NULL);
 143   assert(image_info->signature == MagickSignature);
 144   if (image_info->debug != MagickFalse)
 145     (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",
 146       image_info->filename);
 147   assert(exception != (ExceptionInfo *) NULL);
 148   assert(exception->signature == MagickSignature);
 149   image=AcquireImage(image_info);
 150   if ((image->columns == 0) || (image->rows == 0))
 151     ThrowReaderException(OptionError,"MustSpecifyImageSize");
 152   read_info=CloneImageInfo(image_info);
 153   SetImageInfoBlob(read_info,(void *) NULL,0);
 154   *read_info->magick='\0';
 155   watermark=ReadImage(read_info,exception);
 156   read_info=DestroyImageInfo(read_info);
 157   if (watermark == (Image *) NULL)
 158     return((Image *) NULL);
 159   watermark->depth=MAGICKCORE_QUANTUM_DEPTH;
 160   if (AcquireImageColormap(image,MaxColormapSize) == MagickFalse)
 161     ThrowReaderException(ResourceLimitError,"MemoryAllocationFailed");
 162   if (image_info->ping != MagickFalse)
 163     {
 164       (void) CloseBlob(image);
 165       return(GetFirstImageInList(image));
 166     }
 167   /*
 168     Get hidden watermark from low-order bits of image.
 169   */
 170   c=0;
 171   i=0;
 172   j=0;
 173   i=MAGICKCORE_QUANTUM_DEPTH-1;
 174   depth=MAGICKCORE_QUANTUM_DEPTH;
 175   for (k=image->offset; (i >= 0) && (j < (ssize_t) depth); i--)
 176   {
 177     for (y=0; (y < (ssize_t) image->rows) && (j < (ssize_t) depth); y++)
 178     {
 179       x=0;
 180       for (; (x < (ssize_t) image->columns) && (j < (ssize_t) depth); x++)
 181       {
 182         if ((k/(ssize_t) watermark->columns) >= (ssize_t) watermark->rows)
 183           break;
 184         (void) GetOneVirtualPixel(watermark,k % (ssize_t) watermark->columns,
 185           k/(ssize_t) watermark->columns,&pixel,exception);
 186         q=GetAuthenticPixels(image,x,y,1,1,exception);
 187         if (q == (PixelPacket *) NULL)
 188           break;
 189         indexes=GetAuthenticIndexQueue(image);
 190         switch (c)
 191         {
 192           case 0:
 193           {
 194             SetBit(*indexes,i,GetBit(pixel.red,j));
 195             break;
 196           }
 197           case 1:
 198           {
 199             SetBit(*indexes,i,GetBit(pixel.green,j));
 200             break;
 201           }
 202           case 2:
 203           {
 204             SetBit(*indexes,i,GetBit(pixel.blue,j));
 205             break;
 206           }
 207         }
 208         if (SyncAuthenticPixels(image,exception) == MagickFalse)
 209           break;
 210         c++;
 211         if (c == 3)
 212           c=0;
 213         k++;
 214         if (k == (ssize_t) (watermark->columns*watermark->columns))
 215           k=0;
 216         if (k == image->offset)
 217           j++;
 218       }
 219     }
 220     status=SetImageProgress(image,LoadImagesTag,i,depth);
 221     if (status == MagickFalse)
 222       break;
 223   }
 224   watermark=DestroyImage(watermark);
 225   (void) SyncImage(image);
 226   return(GetFirstImageInList(image));
 227 }
 228 \f
 229 /*
 230 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 231 %                                                                             %
 232 %                                                                             %
 233 %                                                                             %
 234 %   R e g i s t e r S T E G A N O I m a g e                                   %
 235 %                                                                             %
 236 %                                                                             %
 237 %                                                                             %
 238 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 239 %
 240 %  RegisterSTEGANOImage() adds attributes for the STEGANO image format to
 241 %  the list of supported formats.  The attributes include the image format
 242 %  tag, a method to read and/or write the format, whether the format
 243 %  supports the saving of more than one frame to the same file or blob,
 244 %  whether the format supports native in-memory I/O, and a brief
 245 %  description of the format.
 246 %
 247 %  The format of the RegisterSTEGANOImage method is:
 248 %
 249 %      size_t RegisterSTEGANOImage(void)
 250 %
 251 */
 252 ModuleExport size_t RegisterSTEGANOImage(void)
 253 {
 254   MagickInfo
 255     *entry;
 256
 257   entry=SetMagickInfo("STEGANO");
 258   entry->decoder=(DecodeImageHandler *) ReadSTEGANOImage;
 259   entry->format_type=ExplicitFormatType;
 260   entry->description=ConstantString("Steganographic image");
 261   entry->module=ConstantString("STEGANO");
 262   (void) RegisterMagickInfo(entry);
 263   return(MagickImageCoderSignature);
 264 }
 265 \f
 266 /*
 267 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 268 %                                                                             %
 269 %                                                                             %
 270 %                                                                             %
 271 %   U n r e g i s t e r S T E G A N O I m a g e                               %
 272 %                                                                             %
 273 %                                                                             %
 274 %                                                                             %
 275 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 276 %
 277 %  UnregisterSTEGANOImage() removes format registrations made by the
 278 %  STEGANO module from the list of supported formats.
 279 %
 280 %  The format of the UnregisterSTEGANOImage method is:
 281 %
 282 %      UnregisterSTEGANOImage(void)
 283 %
 284 */
 285 ModuleExport void UnregisterSTEGANOImage(void)
 286 {
 287   (void) UnregisterMagickInfo("STEGANO");
 288 }