Analyzing digital photos and video images for alterations

[jee]

Neal Krawetz, a researcher and computer security consultant, gave an interesting presentation at the BlackHat security conference in Las Vegas about analyzing digital photographs and video images for alterations and enhancements.

Using a program he wrote (and provided on the conference CD-ROM) Krawetz could print out the quantization tables in a JPEG file (that indicate how the image was compressed) and determine the last tool that created the image -- that is, the make and model of the camera if the image is original or the version of Photoshop that was used to alter and re-save the image.

Comparing that data to the metadata embedded in the image he could determine if the photo was original or had been re-saved or altered. Then, using error level analysis of an image he could determine what were the last parts of an image that were added or modified.

http://blog.wired.com/27bstroke6/2007/0 ... s-ana.html

I suppose the most interesting part of dear olde Neal, is the fact that he reversed his stance on the doctored Al-Qaeda tapes. Probably scared of IntelCenter, a private intelligence group made up of Pentagon affiliated ex-spooks.

[Tribble]

Wouldn't you be? On some sites when I upload jpg files taken from my camera, it lists the make, model, time the pic was taken, --> here is an example

Make: OLYMPUS IMAGING CORP.
Model: SP510UZ
Shutter Speed: 10/5000 second
F Number: F/3.3
Focal Length: 14 mm
ISO Speed: 400
Date Picture Taken: Aug 24, 2007, 3:59:55 PM

So I am sure they can read other data from the files. But you will find someone who can edit that data and make it seem like the file was not edited. People are clever these days.

[jee]

From what I can understand Krawetz's programme can actually pick up the editing. There is a link to his code for those interested and who will understand it, also a pdf file with his presentation on the site i quoted.

[OnlyOneKenobi]

From what I can understand Krawetz's programme can actually pick up the editing. There is a link to his code for those interested and who will understand it, also a pdf file with his presentation on the site i quoted.

It's not exactly foolproof, a pic could be printed out and then simply rescanned, making it an "original" all over again.