// // PPMdecode.java // /* PPMdecode.java programmed by Richard R, Shiffman, 08-19-01 PPMdecode is used to decode a message or information hidden in a PPM picture. The Hidden information is serially encoded in the LSBÕs of the RGB parts of each pixel in the PPM image. The graphical interface to this program was generated by Symantec's Visual Cafe version 2.0, and AWT is used for the window system. The PPMdecode class is an extension of the Frame class for use as the main window of this application. */ import java.awt.*; import java.io.*; public class PPMdecode extends Frame { boolean debug = true; public PPMdecode() { super(); //{{INIT_MENUS menuBar = new java.awt.MenuBar(); fileMenu = new java.awt.Menu("File"); fileMenu.add("OpenImg..."); //fileMenu.add("OpenMes..."); fileMenu.addSeparator(); fileMenu.add("Save_messageÉ"); fileMenu.addSeparator(); fileMenu.add("Quit"); menuBar.add(fileMenu); setMenuBar(menuBar); //}} //{{INIT_CONTROLS setLayout(null); addNotify(); resize(insets().left + insets().right + 480,insets().top + insets().bottom + 250); setFont(new Font("Dialog", Font.PLAIN, 10)); setBackground(new Color(12632256)); decodeButton = new java.awt.Button("Decode"); decodeButton.reshape(insets().left + 210,insets().top + 192,60,23); decodeButton.setForeground(new Color(0)); decodeButton.setBackground(new Color(16777215)); add(decodeButton); Output_File = new java.awt.TextField(); Output_File.reshape(insets().left + 8,insets().top + 152,450,23); Output_File.setFont(new Font("Dialog", Font.PLAIN, 10)); Output_File.setForeground(new Color(0)); Output_File.setBackground(new Color(16777215)); Output_File.setEditable( false ); add(Output_File); Input_Image = new java.awt.TextField(); Input_Image.reshape(insets().left + 8,insets().top + 42,450,23); Input_Image.setFont(new Font("Dialog", Font.PLAIN, 10)); Input_Image.setBackground(new Color(16777215)); Input_Image.setEditable( false ); add(Input_Image); label1 = new java.awt.Label("Input Image is :"); label1.reshape(insets().left + 8,insets().top + 17,97,22); add(label1); label3 = new java.awt.Label("Output File:"); label3.reshape(insets().left + 8,insets().top + 126,100,23); add(label3); setTitle("PPMdecode window"); //}} show(); } public synchronized void show() { move(50, 50); super.show(); } public boolean handleEvent(Event event) { if (event.id == Event.WINDOW_DESTROY) { hide(); // hide the Frame dispose(); // tell windowing system to free resources System.exit(0); // exit return true; } return super.handleEvent(event); } // public boolean action(Event event, Object arg) { String Label = (String) arg; if (event.target instanceof MenuItem) { if (Label.equalsIgnoreCase("Quit")) { System.exit(0); } else if (Label.equalsIgnoreCase("OpenImg...")) { selectedOpen_Img(); return true; } else if (Label.equalsIgnoreCase("Save_messageÉ")) { selectedDestination(); return true; } } if (event.target instanceof Button) { if (Label.equalsIgnoreCase("Decode")) { selectedDecode( ); return true; } } return super.action(event, arg); } public static void main( String args[ ]) { new PPMdecode(); } //{{DECLARE_MENUS java.awt.MenuBar menuBar; java.awt.Menu fileMenu; //}} //{{DECLARE_CONTROLS java.awt.Button decodeButton; java.awt.TextField Input_Message; java.awt.TextField Output_File; java.awt.TextField Input_Image; java.awt.Label label1; java.awt.Label label2; java.awt.Label label3; //}} // String srcImgFile, messageFile, dstImgFile; public void selectedOpen_Img() { FileDialog fDImg = new FileDialog(this, "OpenImg...", FileDialog.LOAD); fDImg.show(); //srcImgFile = fDImg.getDirectory( ) + File.separator + fDImg.getFile( ); srcImgFile = fDImg.getDirectory( ); if (srcImgFile.endsWith( File.separator ) ) srcImgFile = srcImgFile + fDImg.getFile( ); else srcImgFile = srcImgFile + File.separator + fDImg.getFile( ); fDImg = null; if ( debug ) System.out.println( "Image in is: " + srcImgFile ); Input_Image.setText( srcImgFile ); } public void selectedDestination() { FileDialog fDDst = new FileDialog(this, "Destination_File", FileDialog.SAVE); fDDst.show(); //dstImgFile = fDDst.getDirectory( ) + File.separator + fDDst.getFile( ); dstImgFile = fDDst.getDirectory( ); if ( dstImgFile.endsWith( File.separator ) ) dstImgFile = dstImgFile + fDDst.getFile( ); else dstImgFile = dstImgFile + File.separator + fDDst.getFile( ); fDDst = null; if ( debug ) System.out.println( "Destination is: " + dstImgFile ); Output_File.setText( dstImgFile ); } public void selectedDecode( ) { if ( debug ) System.out.println( "Decode Button pushed" ); do_It( ); } // // String srcImgFile, messageFile, dstImgFile; InputStream imgSrc, mesSrc, inI, inM; OutputStream imgDst, outI; long imgCnt, mesCnt ; // bytes remaining in image file and message file void do_It( ) { // This private method preforms the encoding of the messag in the LSBÕs of // the pixels of the input image. long imgSize, mesSize; int bufSize = 1024; File inImg, inMes, outImg; /* InputStream imgSrc, mesSrc, inI, inM; OutputStream imgDst, outI; */ try { if ( srcImgFile.equalsIgnoreCase("null/null") ) srcImgFile = null; if ( dstImgFile.equalsIgnoreCase("null/null") ) dstImgFile = null; inImg = new File( srcImgFile ); outImg = new File( dstImgFile); imgSize = inImg.length( ); imgCnt = imgSize; // Open all the needed files imgSrc = new FileInputStream( inImg ); inI = new BufferedInputStream( imgSrc, bufSize); imgDst = new FileOutputStream( outImg ); outI = new BufferedOutputStream( imgDst, bufSize); if (debug ) System.out.println( "Image size ... imgCnt = " + imgCnt ); // skip PPM file header SkipHdr( inI, outI ); if (debug ) System.out.println( "skipped header ... imgCnt = " + imgCnt ); // decode message in the image file decodeMsg( inI, outI ); if (debug ) System.out.println( " message decoded ... imgCnt = " + imgCnt ); outI.flush( ); } catch( Exception e ) { System.out.println( "File Error " + e ); return; } finally { // No matter what happens, close all the files if ( imgSrc != null ) try { imgSrc.close( ); } catch ( IOException e ) { }; if ( imgDst != null ) try { imgDst.close( ); } catch ( IOException e ) { }; } } // void decodeMsg(InputStream source, OutputStream dest ) throws IOException { byte[ ] buffer; int bytes_read; long msg_len=0; buffer = new byte[ 8 ]; byte mbyt = 0; for( int i = 0; i < 4; i++ ) { // read length of hidden message // msg_len is unsigned, it must be positive. bytes_read = source.read( buffer ); if( bytes_read == -1 ) throw new IOException("Bad Data File"); mbyt = (byte) packByte( buffer ); msg_len |= (long) (mbyt << ( 3-i ) *8) & 0x0000ffffL ; } imgCnt -= 32; System.out.println( "message length is " + msg_len ); lp: while( true ) { // read rest of hidden message. int j; mbyt = 0; for( int i = 0; i < 8; i++ ) { // remember this read is buffered // by the input stream with a 1K buffer !!! buffer[ i ] = (byte) 0; j = source.read( ); if( j == -1 ) break lp; // quit on EOF buffer[ i ] = (byte) j; imgCnt -= 1; } mbyt = (byte) packByte( buffer ); dest.write( mbyt ); if( msg_len <= 0 ) break; // quit when done with message msg_len--; // decr message length } } byte packByte( byte[ ] unpack ) { byte mbyt = 0; for( int i =0; i < 8; i++ ) { //mbyt |= (byte) ((unpack[ i ] & 0x01) << (7 - i)); mbyt |= (byte) ((unpack[ i ] & 0x01) << ( i)); } return mbyt; } // void SkipHdr(InputStream source, OutputStream dest ) throws IOException { byte[ ] buffer; int bytes_read; buffer = new byte[ 1024 ]; //read 1st line. its "p6\n" bytes_read = readToLf( source, buffer ); //read 2nd line, loop if its a comment. otherwise its the parameter line //if its a param. line then its width and higth of picture while( true ) { bytes_read = readToLf( source, buffer ); if( buffer[ 0 ] != (byte)'#' ) break; // break if not a comment } //read last parameter line. its the max pixel value bytes_read = readToLf( source, buffer ); } int readToLf( InputStream scr, byte[] buf ) throws IOException { // read up to (and inculuding) a linefeed int cnt = -1; boolean readFlg = true; while ( readFlg ) { buf[ ++cnt ] = (byte) scr.read( ); if ( buf[ cnt ] == (byte)'\n' ) readFlg = false; } imgCnt -= (cnt + 1); // dec image bytes to read return cnt+1; //Return number of bytes read } }