Talk:Steganography

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Contents

1 Stegonography Easter Egg?

2 Steganography name

3 Factchecking

4 Typo in image filenames

5 Python script for the sample images

6 Steganography / watermarking

7 Terrorism

8 Trees to cat

9 Stego/terrorism report

10 Tree to Cat Example in Delphi

Stegonography Easter Egg?

A Wikipedia easter egg: see Pikes Peak and find the hidden message.

Well, whatever it was, from the timestamps it's got to be one of the following article revisions:

It's in Image:Ppeak-s.jpg (http://en.wikipedia.org/wiki/Image:Ppeak-s.jpg). That was a few years ago, and I've forgotten exactly how I did it. But I know it was some package I found via Google. I did not encrypt the message. Discovery of the package (and the hidden message) is left as an exercise for the reader. <>< tbc 05:48, 10 Mar 2005 (UTC)

Steganography name

The name comes from Johannes Trithemius's Steganographia: a treatise on black magic disguised as a book on cryptography, and is Greek for "hidden writing."

I was under the impression that this claim - orginally made by the Catholic Church - had been refuted. It really is about cryptography - or more generally, 15th century information security, since it branches into peripheral areas such as training couriers to memorise messages. In particular, the so-called spells in Book III were shown by Jim Reed to be cryptograms. In fact many sites today invert the sense of the quote above, and say that it is ostensibly about magic but really about crypto. However I don't know all the details, so does anyone know if there are any parts of the book that are definitively about black magic? Securiger 11:28, 4 Feb 2004 (UTC)

Factchecking

Two more problems(?) with factual claims here.

1) Bacon certainly suggested the use of different type faces to carry information. Was there also discussion of hand written stego? Have removed the handwritten part pending clarification.

2) I have heard several claims about the frequency of stego'd images on the Internet. None has been credible on second look. I have changed the claim, to an expression of indeterminacy. Can someone provide something credible on this point?

ww 16:30, 20 Apr 2004 (UTC)

Typo in image filenames

The images are named Stenography- instead of Steganography-. Arvindn 17:11, 20 Apr 2004 (UTC)

Arvindn, Sorry. I missed that entirely. Is this in response to 2 above, or something else? ww 17:39, 20 Apr 2004 (UTC)

Nothing related to the above. I mean the images in the article -- the tree and the cat. Typo in the filenames. Arvindn 17:43, 20 Apr 2004 (UTC)

I created the images and wrote a short one line stenography article to go with them. Then after someone claimed that stenography was to do with handwriting, I found out that it was called steganography. "Steganography" is a good example of steganography, since the "ga" is well hidden in there and hard to see... Κσυπ Cyp 08:33, 21 Apr 2004 (UTC)

Python script for the sample images

Try it yourself!

I converted png to bmp and tried

$ python -c 'import sys; a=sys.stdin.read(); sys.stdout.write(a[:54] + "".join(map(lambda(x): chr((ord(x)&3)*85), a[54:])))' < StenographyOriginal.bmp > StenographyRecovered.bmp

It worked :-) (54 is the bmp header length) Arvindn 17:43, 20 Apr 2004 (UTC)

I can't get this to work. :-/ Quizically, I constructed my own C-hack to do this for me and got the same result as I got with your script -- a distorted picture of the trees. Somehow, this implies I've understood the process and done the right thing, but something else must be wrong... What size is the original bmp you are working with? Mine is 120,054 bytes. Also, byte order might make a difference, but I though ANDing with 128+64 instead of 1+2 would solve that, but nope.. ✏ Sverdrup 14:33, 13 Oct 2004 (UTC)

It works for me. I obtained the BMP using the "convert" utility from ImageMagick; I also get the length of the original bmp to be 120,054 (md5sum: 7e4ce7288ab0bcf6231c2ce653fbf9b9 StenographyOriginal.bmp). I can't think of why it doesn't work for you, though...— Matt 14:50, 13 Oct 2004 (UTC)

Well, I feel stupid; naturally it was the PNG->BMP conversion (which I could find no fault in in the first inspection) Apple's Preview application _of course_ dithers the image, even though I just asked for a format conversion with the same colour depth! :-/ convert solved the thing for me; thanks a lot. ✏ Sverdrup 15:09, 13 Oct 2004 (UTC)

Ah, cool. Any ideas on the "Easter Egg" thing above, by the way?

If there's something, it's hard to find. It seems though that it's the picture [1] (http://www.geocities.com/tbchambers/images/ppeak-s.jpg) that contains something; regardless of how you AND the other picture (http://www.geocities.com/tbchambers/images/PPeak010407a.jpg), a rough outline resembling the original can be seen. The first image, however, shows no resemblance to the original (to me) when ANDing with 1 or 2 or 3. ✏ Sverdrup 16:06, 13 Oct 2004 (UTC)

Steganography / watermarking

It is very unclear what the following paragraph:

"Steganography can be used for digital watermarking, where a message (being simply an identifier) is hidden in an image so that its source can be tracked or verified. In fact, in Japan "... the Content ID Forum and the Digital Content Association of Japan started tests with a system of digital watermarks 'to prevent piracy' (The Japan Times Online 26-08-2001)."

is doing in this article. First I don't know of any steganographic technique actually used for watermarking. The two have different golas. Second 'tracking' and 'verification' are not usually the main uses for watermarking. It's mainly been copyright protection. Third, many groups and people have tested watermarking algorithms to prevent piracy several years before the Content ID Forum or the Digital Content Association of Japan wake up!

Terrorism

This section is based on a set of rumours. Does the definition for "airplane" include a section about the usage in terrorism?

The section mainly debunks a currently widespread rumour, which happens to be the motive for most current public interest in this topic, including nearly all press coverage. If ninety percent of the population had no interest in aircraft other than their usage in terrorism, then that article should indeed include such a section; but unlike steganography, that is not the case. Additionally, this section notes that AQ's own training manuals claim that they do use invisible ink, which is closely related and rather interesting. Securiger 03:51, 13 Aug 2004 (UTC)

I agree with Securiger; the terrorism rumours are relevant here. Also, although the section discusses a set of rumours, they are carefully attributed. — Matt 13:31, 13 Aug 2004 (UTC)

And I will chime (not chyme) in as well. Securiger is correct in my view. ww 17:02, 13 Aug 2004 (UTC)

Trees to cat

OK, I give up. I am trying to reveal the cat image by manipulating the tree image. I downloaded the tree image, and opened it with GraphicConverter on my Macintosh. Any hints on what the next step is? How do I perform the "logical and" step?

Yea, n00b. :)

There doesn't seem to be a way to do this in GC; I have version 4.x though, and if you have version 5, there _might_ be a way to do it in GC.

Logical and is essensially this:

The image is a 32-bit image, which means each of the colour channels (Red, Green, Blue) has one byte of information per pixel. Each of these bytes is a sequence of eight bits. When we Do a logical and with 3 (1 + 2 = 3), we keep the two lowest bits:

byte AND 3 => result

01001101 & 00000011 => 00000001

The higher bits have higher significance, and hence contribute more to the hue/brightness of each pixel; we can use the least significant bits for extra information that is hidden in the picture. ✏ Sverdrup 15:32, 13 Oct 2004 (UTC)

I agree. Including terrorism here only support fear-based politics and obscuring computing social image.

Stego/terrorism report

A recent news story:

"...An internal report obtained by The Canadian Press gives credence to the long-rumoured possibility Osama bin Laden's terrorist network and other extremist groups are using a technique known as steganography to hide the existence of sensitive communications...

...A heavily edited copy of the January 2004 report, Computer-assisted and Digital Steganography: Use by Al-Qaeda and Affiliated Terrorist Organizations, was recently obtained from the Mounties under the Access to Information Act. Among the material stripped from the document is information on how best to detect, extract and view surreptitious messages... — [2] (http://www.theglobeandmail.com/servlet/story/RTGAM.20041208.whidden1208/BNStory/National/)

Because of this, we may soon have to update the "No corroborating evidence has been produced by any other source." note in this article 's "Rumoured usage in terrorism" section. I'd like to find out a little more about this report first, though! — Matt Crypto 15:15, 10 Dec 2004 (UTC)

Tree to Cat Example in Delphi

I was facinated by this article and decided to produce a quick application that would convert the tree, per the instructions, into a cat. The final result lacks a lot of color definition, so I would imagine there is still a key part of the algorytm missing from the instructions.

I'll post up the source code if someone can tell me where to put it. In the mean time here's a few bitmaps of the results.

1. Original Image Missing image
JohnC_Steganography_1.jpg
Image:JohnC_Steganography_1.jpg

2. Image AND 3 (boolean operation) Missing image
JohnC_Steganography_2_1.jpg
Image:JohnC_Steganography_2_1.jpg

3. Image Multiplyed by 85 Missing image
JohnC_Steganography_2_2.jpg
Image:JohnC_Steganography_2_2.jpg

John C. Lieurance -- March 2005

That's really cool. Who came up with the original images? And has anyone managed to work out the Pikes Peak Easter Egg yet? (This is way beyond my meagre technical skills). Lisiate 02:20, 4 Apr 2005 (UTC)

Try to put your program in wikisource.org or sourceforge.net Edggar

Well I tried to upload the application and source as a Zip file to the Wikisource and the server wouldn't have it. Its restricted to image / sound files. Sorry but I don't want to go through the trouble of creating a project in sourceforge.net either. I will email anyone the program that wants it, just follow my author link and you'll find my last known email address.

I've been giving more thought to the end result, a red image, and suspect that the final result needs a 256 color palette. Its possible to build such a palette from the original image and re-apply it to the red image using the variance of the red scale, 0 to 255, as a color index. If I get some free time I'll add such a modification to my application to test the theory. John C. Lieurance -- April 24, 2005

Update on the palette. The original tree image contains 13,323 colors. The original cat image contains 40 and my Delphi driven image contains 4 colors. There's no easy way to move the color palette over from the 13,323 color image, but I did move the original cat image (40 colors) over to my Delphi driven image. The results were quite interesting. It's closer to what it needs to be but its still a long ways off...

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Johnc_tree_palette_applied.png
Image:Johnc_tree_palette_applied.png

Here's the image from the top right after its been over exposed.

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Johnc_Cat_Over_Exposed.png
Image:Johnc_Cat_Over_Exposed.png

John C. Lieurance -- April 24, 2005

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