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  1. #1
    stegano is offline Member
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    Default problem with encryption in steganography

    Hi,i'm currently doing my fyp project in steganography.i'm done with all code and my last part is to add an encryption code into steganography class.anyone can help me?here i put my code.
    XML Code:
    /*
     *import list
     */
    import java.io.File;
    
    import java.awt.Point;
    import java.awt.Graphics2D;
    import java.awt.image.BufferedImage;
    import java.awt.image.WritableRaster;
    import java.awt.image.DataBufferByte;
    
    import javax.imageio.ImageIO;
    import javax.swing.JOptionPane;
    
    /*
     *Class Steganography
     */
    public class Steganography
    {
    	
    	/*
    	 *Steganography Empty Constructor
    	 */
    	public Steganography()
    	{
    	}
    	
    	/*
    	 *Encrypt an image with text, the output file will be of type .png
    	 *@param path		 The path (folder) containing the image to modify
    	 *@param original	The name of the image to modify
    	 *@param ext1		  The extension type of the image to modify (jpg, png)
    	 *@param stegan	  The output name of the file
    	 *@param message  The text to hide in the image
    	 *@param type	  integer representing either basic or advanced encoding
    	 */
    	public boolean encode(String path, String original, String ext1, String stegan, String message)
    	{
    		String			file_name 	= image_path(path,original,ext1);
    		BufferedImage 	image_orig	= getImage(file_name);
    		
    		//user space is not necessary for Encrypting
    		BufferedImage image = user_space(image_orig);
    		image = add_text(image,message);
    		
    		return(setImage(image,new File(image_path(path,stegan,"png")),"png"));
    	}
    	
    	/*
    	 *Decrypt assumes the image being used is of type .png, extracts the hidden text from an image
    	 *@param path   The path (folder) containing the image to extract the message from
    	 *@param name The name of the image to extract the message from
    	 *@param type integer representing either basic or advanced encoding
    	 */
    	public String decode(String path, String name)
    	{
    		byte[] decode;
    		try
    		{
    			//user space is necessary for decrypting
    			BufferedImage image  = user_space(getImage(image_path(path,name,"png")));
    			decode = decode_text(get_byte_data(image));
    			return(new String(decode));
    		}
    		catch(Exception e)
    		{
    			JOptionPane.showMessageDialog(null, 
    				"There is no hidden message in this image!","Error",
    				JOptionPane.ERROR_MESSAGE);
    			return "";
    		}
    	}
    	
    	/*
    	 *Returns the complete path of a file, in the form: path\name.ext
    	 *@param path   The path (folder) of the file
    	 *@param name The name of the file
    	 *@param ext	  The extension of the file
    	 *@return A String representing the complete path of a file
    	 */
    	private String image_path(String path, String name, String ext)
    	{
    		return path + "/" + name + "." + ext;
    	}
    	
    	/*
    	 *Get method to return an image file
    	 *@param f The complete path name of the image.
    	 *@return A BufferedImage of the supplied file path
    	 *@see	Steganography.image_path
    	 */
    	private BufferedImage getImage(String f)
    	{
    		BufferedImage 	image	= null;
    		File 		file 	= new File(f);
    		
    		try
    		{
    			image = ImageIO.read(file);
    		}
    		catch(Exception ex)
    		{
    			JOptionPane.showMessageDialog(null, 
    				"Image could not be read!","Error",JOptionPane.ERROR_MESSAGE);
    		}
    		return image;
    	}
    	
    	/*
    	 *Set method to save an image file
    	 *@param image The image file to save
    	 *@param file	  File  to save the image to
    	 *@param ext	  The extension and thus format of the file to be saved
    	 *@return Returns true if the save is succesful
    	 */
    	private boolean setImage(BufferedImage image, File file, String ext)
    	{
    		try
    		{
    			file.delete(); //delete resources used by the File
    			ImageIO.write(image,ext,file);
    			return true;
    		}
    		catch(Exception e)
    		{
    			JOptionPane.showMessageDialog(null, 
    				"File could not be saved!","Error",JOptionPane.ERROR_MESSAGE);
    			return false;
    		}
    	}
    	
    	/*
    	 *Handles the addition of text into an image
    	 *@param image The image to add hidden text to
    	 *@param text	 The text to hide in the image
    	 *@return Returns the image with the text embedded in it
    	 */
    	private BufferedImage add_text(BufferedImage image, String text)
    	{
    		//convert all items to byte arrays: image, message, message length
    		byte img[]  = get_byte_data(image);
    		byte msg[] = text.getBytes();
    		byte len[]   = bit_conversion(msg.length);
    		try
    		{
    			encode_text(img, len,  0); //0 first positiong
    			encode_text(img, msg, 32); //4 bytes of space for length: 4bytes*8bit = 32 bits
    		}
    		catch(Exception e)
    		{
    			JOptionPane.showMessageDialog(null, 
    "Target File cannot hold message!", "Error",JOptionPane.ERROR_MESSAGE);
    		}
    		return image;
    	}
    	
    	/*
    	 *Creates a user space version of a Buffered Image, for editing and saving bytes
    	 *@param image The image to put into user space, removes compression interferences
    	 *@return The user space version of the supplied image
    	 */
    	private BufferedImage user_space(BufferedImage image)
    	{
    		//create new_img with the attributes of image
    		BufferedImage new_img  = new BufferedImage(image.getWidth(), image.getHeight(), BufferedImage.TYPE_3BYTE_BGR);
    		Graphics2D	graphics = new_img.createGraphics();
    		graphics.drawRenderedImage(image, null);
    		graphics.dispose(); //release all allocated memory for this image
    		return new_img;
    	}
    	
    	/*
    	 *Gets the byte array of an image
    	 *@param image The image to get byte data from
    	 *@return Returns the byte array of the image supplied
    	 *@see Raster
    	 *@see WritableRaster
    	 *@see DataBufferByte
    	 */
    	private byte[] get_byte_data(BufferedImage image)
    	{
    		WritableRaster raster   = image.getRaster();
    		DataBufferByte buffer = (DataBufferByte)raster.getDataBuffer();
    		return buffer.getData();
    	}
    	
    	/*
    	 *Gernerates proper byte format of an integer
    	 *@param i The integer to convert
    	 *@return Returns a byte[4] array converting the supplied integer into bytes
    	 */
    	private byte[] bit_conversion(int i)
    	{
    		//originally integers (ints) cast into bytes
    		//byte byte7 = (byte)((i & 0xFF00000000000000L) >>> 56);
    		//byte byte6 = (byte)((i & 0x00FF000000000000L) >>> 48);
    		//byte byte5 = (byte)((i & 0x0000FF0000000000L) >>> 40);
    		//byte byte4 = (byte)((i & 0x000000FF00000000L) >>> 32);
    		
    		//only using 4 bytes
    		byte byte3 = (byte)((i & 0xFF000000) >>> 24); //0
    		byte byte2 = (byte)((i & 0x00FF0000) >>> 16); //0
    		byte byte1 = (byte)((i & 0x0000FF00) >>> 8 ); //0
    		byte byte0 = (byte)((i & 0x000000FF)	   );
    		//{0,0,0,byte0} is equivalent, since all shifts >=8 will be 0
    		return(new byte[]{byte3,byte2,byte1,byte0});
    	}
    	
    	/*
    	 *Encode an array of bytes into another array of bytes at a supplied offset
    	 *@param image	 Array of data representing an image
    	 *@param addition Array of data to add to the supplied image data array
    	 *@param offset	  The offset into the image array to add the addition data
    	 *@return Returns data Array of merged image and addition data
    	 */
    	private byte[] encode_text(byte[] image, byte[] addition, int offset)
    	{
    		//check that the data + offset will fit in the image
    		if(addition.length + offset > image.length)
    		{
    			throw new IllegalArgumentException("File not long enough!");
    		}
    		//loop through each addition byte
    		for(int i=0; i<addition.length; ++i)
    		{
    			//loop through the 8 bits of each byte
    			int add = addition[i];
    			for(int bit=7; bit>=0; --bit, ++offset) //ensure the new offset value carries on through both loops
    			{
    				//assign an integer to b, shifted by bit spaces AND 1
    				//a single bit of the current byte
    				int b = (add >>> bit) & 1;
    				//assign the bit by taking: [(previous byte value) AND 0xfe] OR bit to add
    				//changes the last bit of the byte in the image to be the bit of addition
    				image[offset] = (byte)((image[offset] & 0xFE) | b );
    			}
    		}
    		return image;
    	}
    	
    	/*
    	 *Retrieves hidden text from an image
    	 *@param image Array of data, representing an image
    	 *@return Array of data which contains the hidden text
    	 */
    	private byte[] decode_text(byte[] image)
    	{
    		int length = 0;
    		int offset  = 32;
    		//loop through 32 bytes of data to determine text length
    		for(int i=0; i<32; ++i) //i=24 will also work, as only the 4th byte contains real data
    		{
    			length = (length << 1) | (image[i] & 1);
    		}
    		
    		byte[] result = new byte[length];
    		
    		//loop through each byte of text
    		for(int b=0; b<result.length; ++b )
    		{
    			//loop through each bit within a byte of text
    			for(int i=0; i<8; ++i, ++offset)
    			{
    				//assign bit: [(new byte value) << 1] OR [(text byte) AND 1]
    				result[b] = (byte)((result[b] << 1) | (image[offset] & 1));
    			}
    		}
    		return result;
    	}
    }

  2. #2
    quad64bit's Avatar
    quad64bit is offline Moderator
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    Default

    ...last part is to add an encryption code into steganography class. anyone can help me?
    Sure.
    Java Code:
    private boolean encrypt(byte[] data){
        return true;
    }
    I've taken the liberty of adding encryption code.

  3. #3
    stegano is offline Member
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    Default no encryption happen

    Hi,i'm trying to add the code that you give me for the encryption but there's no encryption happen when i compile it.how to solve it?
    please help me

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