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 1999-2009 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/constitute.h"
  47 #include "magick/exception.h"
  48 #include "magick/exception-private.h"
  49 #include "magick/image.h"
  50 #include "magick/image-private.h"
  51 #include "magick/list.h"
  52 #include "magick/magick.h"
  53 #include "magick/memory_.h"
  54 #include "magick/monitor.h"
  55 #include "magick/monitor-private.h"
  56 #include "magick/quantum-private.h"
  57 #include "magick/static.h"
  58 #include "magick/string_.h"
  59 #include "magick/module.h"
  60 \f
  61 /*
  62 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  63 %                                                                             %
  64 %                                                                             %
  65 %                                                                             %
  66 %   R e a d S T E G A N O I m a g e                                           %
  67 %                                                                             %
  68 %                                                                             %
  69 %                                                                             %
  70 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  71 %
  72 %  ReadSTEGANOImage() reads a steganographic image hidden within another
  73 %  image type.  It allocates the memory necessary for the new Image structure
  74 %  and returns a pointer to the new image.
  75 %
  76 %  The format of the ReadSTEGANOImage method is:
  77 %
  78 %      Image *ReadSTEGANOImage(const ImageInfo *image_info,
  79 %        ExceptionInfo *exception)
  80 %
  81 %  A description of each parameter follows:
  82 %
  83 %    o image_info: the image info.
  84 %
  85 %    o exception: return any errors or warnings in this structure.
  86 %
  87 */
  88
  89 static inline unsigned long MagickMin(const unsigned long x,
  90   const unsigned long y)
  91 {
  92   if (x < y)
  93     return(x);
  94   return(y);
  95 }
  96
  97 static Image *ReadSTEGANOImage(const ImageInfo *image_info,
  98   ExceptionInfo *exception)
  99 {
 100 #define GetBit(alpha,i) MagickMin((((unsigned long) (alpha) >> (unsigned long) \
 101   (i)) & 0x01),16)
 102 #define SetBit(alpha,i,set) (alpha)=(IndexPacket) ((set) != 0 ? \
 103   (unsigned long) (alpha) | (1UL << (unsigned long) (i)) : (unsigned long) \
 104   (alpha) & ~(1UL << (unsigned long) (i)))
 105
 106   Image
 107     *image,
 108     *watermark;
 109
 110   ImageInfo
 111     *read_info;
 112
 113   long
 114     c,
 115     i,
 116     j,
 117     k,
 118     y;
 119
 120   MagickBooleanType
 121     status;
 122
 123   PixelPacket
 124     pixel;
 125
 126   register IndexPacket
 127     *indexes;
 128
 129   register long
 130     x;
 131
 132   register PixelPacket
 133     *q;
 134
 135   unsigned long
 136     depth;
 137
 138   /*
 139     Initialize Image structure.
 140   */
 141   assert(image_info != (const ImageInfo *) NULL);
 142   assert(image_info->signature == MagickSignature);
 143   if (image_info->debug != MagickFalse)
 144     (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",
 145       image_info->filename);
 146   assert(exception != (ExceptionInfo *) NULL);
 147   assert(exception->signature == MagickSignature);
 148   image=AcquireImage(image_info);
 149   if ((image->columns == 0) || (image->rows == 0))
 150     ThrowReaderException(OptionError,"MustSpecifyImageSize");
 151   read_info=CloneImageInfo(image_info);
 152   SetImageInfoBlob(read_info,(void *) NULL,0);
 153   *read_info->magick='\0';
 154   watermark=ReadImage(read_info,exception);
 155   read_info=DestroyImageInfo(read_info);
 156   if (watermark == (Image *) NULL)
 157     return((Image *) NULL);
 158   watermark->depth=MAGICKCORE_QUANTUM_DEPTH;
 159   if (AcquireImageColormap(image,MaxColormapSize) == MagickFalse)
 160     ThrowReaderException(ResourceLimitError,"MemoryAllocationFailed");
 161   if (image_info->ping != MagickFalse)
 162     {
 163       (void) CloseBlob(image);
 164       return(GetFirstImageInList(image));
 165     }
 166   /*
 167     Get hidden watermark from low-order bits of image.
 168   */
 169   c=0;
 170   i=0;
 171   j=0;
 172   i=MAGICKCORE_QUANTUM_DEPTH-1;
 173   depth=MAGICKCORE_QUANTUM_DEPTH;
 174   for (k=image->offset; (i >= 0) && (j < (long) depth); i--)
 175   {
 176     for (y=0; (y < (long) image->rows) && (j < (long) depth); y++)
 177     {
 178       x=0;
 179       for (; (x < (long) image->columns) && (j < (long) depth); x++)
 180       {
 181         if ((k/(long) watermark->columns) >= (long) watermark->rows)
 182           break;
 183         (void) GetOneVirtualPixel(watermark,k % (long) watermark->columns,
 184           k/(long) watermark->columns,&pixel,exception);
 185         q=GetAuthenticPixels(image,x,y,1,1,exception);
 186         if (q == (PixelPacket *) NULL)
 187           break;
 188         indexes=GetAuthenticIndexQueue(image);
 189         switch (c)
 190         {
 191           case 0:
 192           {
 193             SetBit(*indexes,i,GetBit(pixel.red,j));
 194             break;
 195           }
 196           case 1:
 197           {
 198             SetBit(*indexes,i,GetBit(pixel.green,j));
 199             break;
 200           }
 201           case 2:
 202           {
 203             SetBit(*indexes,i,GetBit(pixel.blue,j));
 204             break;
 205           }
 206         }
 207         if (SyncAuthenticPixels(image,exception) == MagickFalse)
 208           break;
 209         c++;
 210         if (c == 3)
 211           c=0;
 212         k++;
 213         if (k == (long) (watermark->columns*watermark->columns))
 214           k=0;
 215         if (k == image->offset)
 216           j++;
 217       }
 218     }
 219     status=SetImageProgress(image,LoadImagesTag,i,depth);
 220     if (status == MagickFalse)
 221       break;
 222   }
 223   watermark=DestroyImage(watermark);
 224   (void) SyncImage(image);
 225   return(GetFirstImageInList(image));
 226 }
 227 \f
 228 /*
 229 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 230 %                                                                             %
 231 %                                                                             %
 232 %                                                                             %
 233 %   R e g i s t e r S T E G A N O I m a g e                                   %
 234 %                                                                             %
 235 %                                                                             %
 236 %                                                                             %
 237 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 238 %
 239 %  RegisterSTEGANOImage() adds attributes for the STEGANO image format to
 240 %  the list of supported formats.  The attributes include the image format
 241 %  tag, a method to read and/or write the format, whether the format
 242 %  supports the saving of more than one frame to the same file or blob,
 243 %  whether the format supports native in-memory I/O, and a brief
 244 %  description of the format.
 245 %
 246 %  The format of the RegisterSTEGANOImage method is:
 247 %
 248 %      unsigned long RegisterSTEGANOImage(void)
 249 %
 250 */
 251 ModuleExport unsigned long RegisterSTEGANOImage(void)
 252 {
 253   MagickInfo
 254     *entry;
 255
 256   entry=SetMagickInfo("STEGANO");
 257   entry->decoder=(DecodeImageHandler *) ReadSTEGANOImage;
 258   entry->format_type=ExplicitFormatType;
 259   entry->description=ConstantString("Steganographic image");
 260   entry->module=ConstantString("STEGANO");
 261   (void) RegisterMagickInfo(entry);
 262   return(MagickImageCoderSignature);
 263 }
 264 \f
 265 /*
 266 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 267 %                                                                             %
 268 %                                                                             %
 269 %                                                                             %
 270 %   U n r e g i s t e r S T E G A N O I m a g e                               %
 271 %                                                                             %
 272 %                                                                             %
 273 %                                                                             %
 274 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 275 %
 276 %  UnregisterSTEGANOImage() removes format registrations made by the
 277 %  STEGANO module from the list of supported formats.
 278 %
 279 %  The format of the UnregisterSTEGANOImage method is:
 280 %
 281 %      UnregisterSTEGANOImage(void)
 282 %
 283 */
 284 ModuleExport void UnregisterSTEGANOImage(void)
 285 {
 286   (void) UnregisterMagickInfo("STEGANO");
 287 }