DissidentX – Censorship resistance tool by Bram Cohen • Hacker News Board

Re: DissidentX – Censorship resistance tool by Bram Cohen

#91

Post by simbolit » Wed, Dec 04, 2013, 11:22 PM UTC

dinkumthinkum wrote: post #76

simbolit wrote: post #36

Earlier quoted context omitted.

i was actually thinking that the "of" was superfluous. since reading [0] on hn (discussion: [1]) i am more and more seeing the use of "because" without preposition. so i was expecting "Q. Why can't it be given more than two alternates for one position to encode more information? A. Because math. See Explanation.txt for a bit more detail." [0] http://www.theatlantic.com/technology/archive/2013/11/englis... [1] https:/…

Yeah, but it's sort of just a comical thing that is getting tired and played out... Let's be honest, it was a slow news day for the Atlantic.

Yes, it was. But i have a degree in linguistics, so i am probably more interested in this than the general population. :-)

Re: DissidentX – Censorship resistance tool by Bram Cohen

#92

Post by dinkumthinkum » Fri, Dec 06, 2013, 12:41 AM UTC

onetwofiveten wrote: post #83

dinkumthinkum wrote: post #75

Earlier quoted context omitted.

:( Are you one of those people that doesn't like to call things what they are? I have noticed many problems in life are due to people know wanting to call things what they are.

Are you one of those people who thinks he knows an obvious truth that everyone else ignores for some reason?

No.

Re: DissidentX – Censorship resistance tool by Bram Cohen

#93

Post by danbruc » Fri, Dec 06, 2013, 1:55 AM UTC

chongli wrote: post #85

danbruc wrote: post #84

Earlier quoted context omitted.

Not really. Encrypting the message will yield uniformly distributed noise and that is a very rare in nature. So if you attempt to hide an encrypted message in the least significant bits of images, audio recordings or video it is as easy to detect as plain text messages if not even easier.

Then don't use every LSB in the image; use a low percentage. Just a guess, but I bet if you applied your stego detection algorithm to a large sampling of random images on the internet, you'd find a significant false positive rate. Just hide your messages in the false positives.

As already mentioned by others - hiding small amounts of data is easy, the challenge is to hide nontrivial amounts of data. There are algorithms that (try to) compensate statistical changes introduced by hiding data. One approach is to only use half of the available bit for hiding data and modifying the other half in a way to preserve a set of statistical properties.

It is probably not a good idea to hide data in images available on the internet because this enables direct comparison of the same image with and without hidden data.