[Steganography] Message hidden in image

[Ian]

I don't know if I have time to complete this, but it is a great idea and we should offer prizes in the future if this catches on. And by the way, DarkstaR is a sexy ass beast.

E4E5B1E4B9B1B1B2E6AFEDEFE3AEEEE9E2E5F4F3E1F0AEF0F4AFAFBAF0F4F4E8

[DarkstaR]

(11-07-2009 06:13 PM)Ian Wrote:  I don't know if I have time to complete this, but it is a great idea and we should offer prizes in the future if this catches on. And by the way, DarkstaR is a sexy ass beast.

E4E5B1E4B9B1B1B2E6AFEDEFE3AEEEE9E2E5F4F3E1F0AEF0F4AFAFBAF0F4F4E8

Ian is fucking pro.

Show me a program to show how you found it, and you win. Haha.

[Ian]

Dark, you gotta decode my hex string for the source

[DarkstaR]

Wow, Ian, thats a simpler way of doing it!

Nest time I'll be sure to throw in some garbage values on the alpha pixels! Your codes simpler than mine :o

Ians

Code:

Bitmap changed = new Bitmap(Image.FromFile(@"..\..\unknownmessage.png"));
Stack<char> chars = new Stack<char>();
for (int x = 0; x < changed.Width; x++)
{
    for (int y = 0; y < changed.Height; y++)
    {
        var changedPixel = changed.GetPixel(x, y);

        if (changedPixel.A < 255 && changedPixel.A >= (128 + 32))
        {
            chars.Push(Convert.ToChar(changedPixel.A - 128));
        }
    }
}
Console.WriteLine(new string(chars.ToArray()));

Mine

Code:

Dim B As Bitmap = PictureBox1.Image
        Dim Size As Integer = B.GetPixel(B.Width - 1, B.Height - 1).A
        Dim StepX As Integer = B.GetPixel(1, 0).A
        Dim StepY As Integer = B.GetPixel(0, 1).A

        Dim Message As String = ""
        Dim Textnum As Integer

        For x = 2 To B.Width - 2 Step StepX
            For y = 2 To B.Height - 2 Step StepY
                If Textnum > Size - 1 Then GoTo Done
                Message += ChrW(B.GetPixel(B.Width - x, B.Height - y).A - 128)
                Textnum += 1
            Next
        Next

Done:
        MsgBox("The message is:" & vbNewLine & Message)

Seems like I shoulda messed more with alpha bytes at random, because he didnt even need to get the random step value and stuff which I used when looping o:

[Ian]

I was wondering if those two values in the beginning meant anything . It would have been good to randomly alter more, it would have taken me a lot longer then.

[DarkstaR]

(11-08-2009 03:09 PM)Ian Wrote:  I was wondering if those two values in the beginning meant anything . It would have been good to randomly alter more, it would have taken me a lot longer then.

I was just gonna find the average value written to alpha and make every other pixel have that value to make it virtually unnoticable what was what, but I didnt have the time! haha

[Grob]

Since it has already been solved, and that I'm to lazy to do it on my own, do you care to explain both what you've done with the pictures and how Ian solved it? I just read something briefly about chaning one bit in every bite, but that's about it.

[DarkstaR]

I changed the Alpha byte of certain pixels to represent a ASCII character value, basically.