Neal's code is neat and pretty, but chapter and verse is no substitute for open code and side by side checks. A LOT of his output bears a strong resemblence to edge detection (really, look for high frequency signal, it'll show up in every test).
I want to be clear, I have no doubt whatsoever that he's using the techniques as described. I also dont doubt the fundamental thesis that some manipulation can be detected (especially in a trivial case like 'was this image downsized' or 'was this saved by Photoshop instead of a Canon camera', which is obvious from quantization tables if not from the raw EXIF). But some of these techniques feel a little interpret-y. More samples would be great. On Dec 28, 2009, at 3:21 AM, "Rob, grandpa of Ryan, Trevor, Devon & Hannah" <rmsl...@shaw.ca> wrote: > An interesting analysis of a graphic recently used by Victoria's > Secret in their > advertising. This gives chapter and verse of the techniques used, > and results > obtained, demonstrating the ability to determine if an image has > been altered, and > even which parts of an image have been modified, and how. > > http://www.hackerfactor.com/blog/index.php?/archives/322-Body-By-Victoria.html > > I find this particularly interesting because of the apparently > widely held belief that > steganography is "undetectable" without comparision to the original > image. Most > of the "Photoshop disasters" are glaringly obvious to the naked > eye. As this > demonstrates, analysis and detection of modification is easily > accomplished, even > when the differences are not apparent to the human eye. (Well, > except for the > straps. That was pretty stupid ...) > > ====================== (quote inserted randomly by Pegasus Mailer) > rsl...@vcn.bc.ca sl...@victoria.tc.ca rsl...@computercrime.org > I live in my own little world, but it's OK, they know me here. > victoria.tc.ca/techrev/rms.htm blog.isc2.org/isc2_blog/slade/ > index.html > http://blogs.securiteam.com/index.php/archives/author/p1/ > http://twitter.com/NoticeBored http://twitter.com/rslade > _______________________________________________ > Fun and Misc security discussion for OT posts. > https://linuxbox.org/cgi-bin/mailman/listinfo/funsec > Note: funsec is a public and open mailing list. _______________________________________________ Fun and Misc security discussion for OT posts. https://linuxbox.org/cgi-bin/mailman/listinfo/funsec Note: funsec is a public and open mailing list.
