Stupid Guest Tricks

kurtisnelson wrote:If they can see it they can steal it. Watermarks really are the best option.

It part of a course I teach, we talk about Stego and other programs available to imbed a digital signature that enables you (the originator) to prove it is yours!

A lot of companies are resorting to this on just about any type of digital document and/or file.

GRUMPY PIRATE wrote:It part of a course I teach, we talk about Stego and other programs available to imbed a digital signature that enables you (the originator) to prove it is yours!

A lot of companies are resorting to this on just about any type of digital document and/or file.

Steganography is really cool isn't it?

Lasolimu wrote:Steganography is really cool isn't it?

Hmmm, I suppose it depends on your point of view!!

hehehehe

Stego. Gonna look that up when I get home.

Big Wallaby wrote:Stego. Gonna look that up when I get home.

Steganography. "Hidden writing"

It orginated from hiding messages in plain sight, and then later encompassed methods used by intellgence services. (pre-digital age)

When the digital age hit, it took off.

as an example, there are programs available (fairly cheep) that will insert data in the slack space of a file, such as a digital image, which can then be sent as a file attachment to someone via e-mail. the only way you can "retrieve" the data is to have the same software (and sometimes a password) it can be inserted so as to not change the attributes of the carrier object . (be it a picture, or word file)

That is just one aspect of it. Others are inserting a trademark or copywrite mark on protected material (a lot of companies are starting to do this.) you can actually bookmark individual files (and if they end up in the wrong place, trace back to who had that file!)

Sorry, it is one of my more favorite subjects (albet a small one) of the information that I teach and use.

RUM?

In one of my classes I had to present a paper about using Steganography to create a covert file system. It ended up being very inefficient.

Lasolimu wrote:In one of my classes I had to present a paper about using Steganography to create a covert file system. It ended up being very inefficient.

Well, actually there are several programs already available to do that. The methods can vary. some use file slack space method and some use the "least significant bit" replacement method.

the fact that your method was not efficent is not the true reason for using stego, it is the concealment of the data.

But then again, I only touch on it very lightly. I started out in somewhat related field (cryptography) back in the 70's and over the years branched out!

I now find it amusing that some of the popular books (and movies) and using variations of it as a theme and/or plot point.

The inefficiency in this file system wasn't that it was slow(you are right about not wanting it for speed), but that in the number of pictures you needed for it to work. They designed the file system so that one image was one block so you ended up needing a lot of files that were large enough to hold the block. It was about to the point where if you wanted to use it and not look suspicious you needed to be a professional photographer just so you have a reason to have a lot of large pictures. Also you need more pictures so that you could access it multiple times without accessing the same images all the time. It was just overall inefficient so that if you want a covert file system there are better ways.

Hmm, one of the tricks that some of the programs use, is to lower the resolution of the graphic, without changing the outward appearence, freeing up slack space and file slack that the program can use.

Another one is the LSB replacement on a much larger file, like a really high res graphic file. even if you enlarge it with a viewer, it just looks like distortion.

it a lot of fun to play with the stuff, but a bear of a problem when trying to find the stuff!!!

Okay, I am finding this conversation extremely interesting. In a slack space stego, how much information can you usually put into the file?

I know many photos have stegonography in the form of EXIF data... info from the camera (especially in RAW photos) that don't show up in the image, but if I see the EXIF I can see how you shot the photo (aperature, shutter speed, ISO, white balance, where you had your lens set, date and time, etc.) and a lot of other info. Do different file types have different amounts of information you can add?

So many questions, but I don't even know where to start beyond that. Care to give a class?