Screenshot watermarking to reveal identity

[TheWindBringeth]

I came across an interesting WoW thread (removed... saw something I don't like the looks of) by way of Slashdot (http://games.slashdot.org/story/12/0...warcraft-users) which discusses the use of "watermarked" screenshots that contain account and other information embedded within them. I can't confirm that is going on in this particular case, but based on a quick walkthrough it appears that this *may* be true and verified through appropriate technical analysis.

In any case, I think it a legitimate and important privacy topic and one which is not inherently limited to pictures. This type of thing is of course done by printers and some scanners and probably other types of tools/devices which create visual and/or audio output. So there are various scenarios in which someone may assume they are sharing non-revealing content via an anonymous or pseudo-anonymous account but in reality they are sharing watermarked content that can be used to break the anonymity of that account and what is in it.

Be aware. Try to look for this where you can.

[caspian]

I use Gadwin Printscreen. I wonder if it embeds personal info??

[TheWindBringeth]

You could study the program carefully to look for related options. You could examine the files it creates for easily observable metadata stuff. You could even ask just to see what they say. When it comes to steganography though, I think there are some primitive approaches and commonly used approaches that a determined person and/or an imaging professional might be able to find but it quickly become the realm of experts. The reverse process is called steganalysis. Worth reading about even if one doesn't want to try their hands at it. I wouldn't assume that all programs do it.