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Posted 27 Nov 2003

Hide a file in a BMP file (Plus).

, 27 Nov 2003
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Hide a file in a BMP file: extended from the author Ahmed Osama's article.

Sample Image - HideIt2.jpg


After I read the article 'Hiding a text file in a BMP file', I found it very funny, and maybe useful. So I decided to extend it to fit in with any file, any password, and become easy to use.


You can find its principle here: Hiding a text file in a BMP file. Very thanks to Ahmed Osama's idea and good work.

Class Structure

class CBmpHermitCrab
 bool Hermit(const char* pszDestFileName, 
  const char* pszSrcFileName,
  const char* pszPassword=NULL, 
  const char* pszResultFile=NULL); 
 bool IsHermitCrabBMPFile(const char* pszFileName);
 bool RecoverCrabFile(const char* pszFileName, 
  const char* pszPassword=NULL, const char* pszPath=NULL);

It provides three methods to implement the following tasks:

  1. Hermit(). Hides a file in a BMP file.

    The main code:

      for(int i=0;i<(iBinaryLen/8); i++){
         temp= m_binaryMap[(unsigned char) strBufferAll[i]];
         srcBinary[nIndex] = temp[0];
         srcBinary[nIndex+1] =temp[1];
         srcBinary[nIndex+2] =temp[2];
         srcBinary[nIndex+3] =temp[3];
         srcBinary[nIndex+4] =temp[4];
         srcBinary[nIndex+5] =temp[5];
         srcBinary[nIndex+6] =temp[6];
         srcBinary[nIndex+7] =temp[7];
      int mask=254for (i=0 ; i<iBinaryLen ; i++){
          bmpBuffer[i+55]=bmpBuffer[i+55] & mask;
          if (srcBinary[i]=='1')  

    Through our binary table srcBinary and the correct index, we can express a char by using the original pixel color value micro-changed.

  2. RecoverCrabFile(). Recovers hidden file from a HermitCrab ;) BMP file.

    The key code:

     for(j=55+8*nHeadSize; j < 55+8*nHeadSize 
           (unsigned char) ((unsigned char)buffer[j] & 1);
     CString strTemp;
     for(j=55+8*nHeadSize; j < 
  3. IsHermitCrabBMPFile(). Like method 2, but it just recovers the fist 8 bytes, and whether the first two bytes: 'C' and 'H'.

Using the code

  1. Include the BmpHermitCrab.h file.
  2. Generate a CBmpHermitCrab instance.
  3. With the instance, use the Hermit() method to hide a file in a BMP file with optional password and use the RecoverCrabFile() method to recover a file from a 'HermitCrab' BMP file. You can check the BMP file format by IsHermitCrabBMPFile() method.

Hope you enjoy the program!


This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here


About the Author

Neil Xu
Web Developer IT - All
China China
I'm programmer,and love it.

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Comments and Discussions

Generalhmm.... Pin
AuroraX3-Apr-05 20:34
memberAuroraX3-Apr-05 20:34 

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