What is the problem with this code?

Question

0.00/5 (No votes)

See more:

I`m trying to do some c# programming for steganography. i tried to decode but the get ????? instead of the message hidden .

this is Encoding code.

C#

Bitmap img = new Bitmap(textBoxFilePath.Text);

            for (int i = 0; i < img.Width; i++)
            {
                for (int j = 0; j < img.Height; j++)
                {
                    Color pixel = img.GetPixel(i, j);

                    if (i < 1 && j < textBoxMessage.TextLength)
                    {
                        Console.WriteLine("R = [" + i + "][" + j + "] = " + pixel.R);
                        Console.WriteLine("G = [" + i + "][" + j + "] = " + pixel.G);
                        Console.WriteLine("G = [" + i + "][" + j + "] = " + pixel.B);

                        char letter = Convert.ToChar(textBoxMessage.Text.Substring(j, 1));
                        int value = Convert.ToInt32(letter);
                        Console.WriteLine("letter : " + letter + " value : " + value);

                        img.SetPixel(i, j, Color.FromArgb(pixel.R, pixel.G, value));
                    }

                    if (i == img.Width - 1 && j == img.Height - 1)
                    {
                        img.SetPixel(i, j, Color.FromArgb(pixel.R, pixel.G, textBoxMessage.TextLength));
                    }

                }
            }

            SaveFileDialog saveFile = new SaveFileDialog();
            saveFile.Filter = "Image Files (*.png, *.jpg) | *.png; *.jpg";
            saveFile.InitialDirectory = @"C:\Users\metech\Desktop";

            if (saveFile.ShowDialog() == DialogResult.OK)
            {
                textBoxFilePath.Text = saveFile.FileName.ToString();
                pictureBox1.ImageLocation = textBoxFilePath.Text;

                img.Save(textBoxFilePath.Text);
            }
        }

What I have tried:

Decoding code.

C#

private void buttonDecode_Click(object sender, EventArgs e)
{
    Bitmap img = new Bitmap(textBoxFilePath.Text);
    string message = "";

    Color lastpixel = img.GetPixel(img.Width - 1, img.Height - 1);
    int msgLength = lastpixel.B;

    for (int i = 0; i < img.Width; i++)
    {
        for (int j = 0; j < img.Height; j++)
        {
            Color pixel = img.GetPixel(i, j);

            if (i < 1 && j < msgLength)
            {
                int value = pixel.B;
                char c = Convert.ToChar(value);
                string letter = System.Text.Encoding.ASCII.GetString(new byte[] { Convert.ToByte(c) });

                message = message + letter;
            }
        }
    }

    textBoxMessage.Text = message;
}

Posted 10-Nov-16 19:30pm

Member 12844786

Updated 13-Nov-16 16:16pm

Patrice T

v6

Add a Solution

Comments

Tomas Takac 11-Nov-16 2:47am

Do you care to explain how the information is encoded? Seems like the blue component is the unicode value of the character. But I don't get the extra step with ASCII encoding - what is it good for?

Member 12844786 13-Nov-16 9:47am

i tried to use lsb method.

Karthik_Mahalingam 11-Nov-16 5:49am

use debugger

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Patrice T · Answer 1 · 2016-11-10T21:56:00

Quote:
I`m trying to do some c# programming for steganography. i tried to decode but the get ????? instead of the message hidden .

You build the message from channel b where channel b is the message. I have never saw steganography that take a full channel. Please explain your encoding method. With the debugger, you will see exactly what is doing your code. I guess you should show the encoding code to help us to understand what you do.

You should learn to use the debugger as soon as possible. Rather than guessing what your code is doing, It is time to see your code executing and ensuring that it does what you expect.

The debugger allow you to follow the execution line by line, inspect variables and you will see that there is a point where it stop doing what you expect.
Debugger - Wikipedia, the free encyclopedia[^]
Mastering Debugging in Visual Studio 2010 - A Beginner's Guide[^]

The debugger is here to show you what your code is doing and your task is to compare with what it should do.
When the code don't do what is expected, you are close to a bug.

[UpDate]
Never ever use JPEG image format with steganography. Steganography imply lossless compression and JPEG is using a lossy compression.