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DissidentX – Censorship resistance tool by Bram Cohen

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Re: DissidentX – Censorship resistance tool by Bram Cohen

#31

Post by chongli »

DanBC wrote: post #27
chongli wrote: post #25

Earlier quoted context omitted.

Why use cover text? Why not just put ciphertext in a jpeg? Wouldn't that just show up as noise?

Sorry, by cover text I mean anything that is used to hide the hidden text. Thus, the jpeg would be the cover text. Thanks for pointing that out. To answer the question: It shows up as a specific type of noise that's easy to detect. Some of the crypto / math people will be able to explain it much better than I can.

To answer the question: It shows up as a specific type of noise that's easy to detect. Some of the crypto / math people will be able to explain it much better than I can.

Ahhh. What if you were to use a video instead of a still image and only use a handful of pixels (or macroblocks) in each frame, chosen randomly (the random seed exchanged out-of-band)? Seems like that would give you a very high cover:hidden text ratio.

Re: DissidentX – Censorship resistance tool by Bram Cohen

#32

Post by margaretlmarin »

sillysaurus2 wrote: post #21

Judging by the claims and the code, this is a tool created by someone who hasn't read any prior research about steganography. If you trust this, don't be surprised when law enforcement detects that you're using it. I'm surprised to see someone of Bram Cohen's caliber releasing something like this. No one has any business coding security tools unless they've taken time to read forensics whitepapers to look for reasons…

my classmate's sister-in-law makes $79/hr on the laptop. She has been laid off for 5 months but last month her pay was $18942 just working on the laptop for a few hours. look here....... http://www.jobs25.com

Re: DissidentX – Censorship resistance tool by Bram Cohen

#33

Post by im3w1l »

DanBC wrote: post #16
tsaoutourpants wrote: post #5

Stenography is one of the NSA's worst nightmares. Encrypted strings sent over the Internet they know are encrypted, and often know what algorithm and key length. But the fact that any image can contain an encrypted message, and there's know way to know whether or not something exists within, scares the shit out of them. So, good work.

Most steganography is trivially easy to detect. Steganography that is implemented correctly then requires reasonable amounts of cover text, and small amounts of hidden text. NSA fucking loves steganography because most of it is a toy implementation where someone hides text in the LSB of the bytes of a gif or jpeg. The ratio of cover:hidden text is terrible. And the implementer forgot to mention that it's just a toy a…

No most of steg is actually even worse then that: append text/rar to end of other file (many formats are tolerant to extra data at end).

Re: DissidentX – Censorship resistance tool by Bram Cohen

#34

Post by jcarpio »

chongli wrote: post #31
DanBC wrote: post #27

Earlier quoted context omitted.

Sorry, by cover text I mean anything that is used to hide the hidden text. Thus, the jpeg would be the cover text. Thanks for pointing that out. To answer the question: It shows up as a specific type of noise that's easy to detect. Some of the crypto / math people will be able to explain it much better than I can.

To answer the question: It shows up as a specific type of noise that's easy to detect. Some of the crypto / math people will be able to explain it much better than I can. Ahhh. What if you were to use a video instead of a still image and only use a handful of pixels (or macroblocks) in each frame, chosen randomly (the random seed exchanged out-of-band)? Seems like that would give you a very high cover:hidden text rat…

I'd like to know if there's been an implementation of that. I remember reading about such a thing in William Gibson's Pattern Recognition.

Re: DissidentX – Censorship resistance tool by Bram Cohen

#35

Post by rosser »

chongli wrote: post #31
DanBC wrote: post #27

Earlier quoted context omitted.

Sorry, by cover text I mean anything that is used to hide the hidden text. Thus, the jpeg would be the cover text. Thanks for pointing that out. To answer the question: It shows up as a specific type of noise that's easy to detect. Some of the crypto / math people will be able to explain it much better than I can.

To answer the question: It shows up as a specific type of noise that's easy to detect. Some of the crypto / math people will be able to explain it much better than I can. Ahhh. What if you were to use a video instead of a still image and only use a handful of pixels (or macroblocks) in each frame, chosen randomly (the random seed exchanged out-of-band)? Seems like that would give you a very high cover:hidden text rat…

Seems like that would give you a very high cover:hidden text ratio.

It would, but that doesn't change the principles used to detect the steganographically encoded cyphertext. The bits would still be twiddled in the same way, and could be found in the same way.

Re: DissidentX – Censorship resistance tool by Bram Cohen

#36

Post by simbolit »

blueblob wrote: post #26

I love the question in the FAQ: Q. Why can't it be given more than two alternates for one position to encode more information? A. Because of math. See Explanation.txt for a bit more detail. Because of math hilarious

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://news.ycombinator.com/item?id=6765099

Re: DissidentX – Censorship resistance tool by Bram Cohen

#37

Post by simbolit »

dmix wrote: post #13
mcphilip wrote: post #11

Earlier quoted context omitted.

Interestingly enough, stenography was already being decried pre 9/11 as a tool used by terrorists [1]: >"Uncrackable encryption is allowing terrorists — Hamas, Hezbollah, al-Qaida and others — to communicate about their criminal intentions without fear of outside intrusion," FBI Director Louis Freeh said last March during closed-door testimony on terrorism before a Senate panel. "They're thwarting the efforts of law…

The consensus in the infosec community seems to be that most (real) Islamic terrorists haven't been using email or cellphones since ~2003. So any mass-surveillance/SIGINT sales pitch about catching terrorists is mostly bullshit. If they do catch anyone, they are likely not the type of people who could have accomplished anything. It seems to be much more useful for catching other nation-state intelligence spies at wor…

i am also interested in what they use?

Re: DissidentX – Censorship resistance tool by Bram Cohen

#38

Post by phil_2-0 »

mcphilip wrote: post #11
tsaoutourpants wrote: post #5

Stenography is one of the NSA's worst nightmares. Encrypted strings sent over the Internet they know are encrypted, and often know what algorithm and key length. But the fact that any image can contain an encrypted message, and there's know way to know whether or not something exists within, scares the shit out of them. So, good work.

Interestingly enough, stenography was already being decried pre 9/11 as a tool used by terrorists [1]: >"Uncrackable encryption is allowing terrorists — Hamas, Hezbollah, al-Qaida and others — to communicate about their criminal intentions without fear of outside intrusion," FBI Director Louis Freeh said last March during closed-door testimony on terrorism before a Senate panel. "They're thwarting the efforts of law…

> "Uncrackable encryption is allowing terrorists — Hamas, Hezbollah, al-Qaida and others — to communicate about their criminal intentions without fear of outside intrusion,

You succeeded to put 3 different ethnic groups - I should say 2, the last one being an US product - in the same bag and doing then, a misleading association, fucking idiot!

Re: DissidentX – Censorship resistance tool by Bram Cohen

#39

Post by dmix »

nodata wrote: post #24
dmix wrote: post #13

Earlier quoted context omitted.

The consensus in the infosec community seems to be that most (real) Islamic terrorists haven't been using email or cellphones since ~2003. So any mass-surveillance/SIGINT sales pitch about catching terrorists is mostly bullshit. If they do catch anyone, they are likely not the type of people who could have accomplished anything. It seems to be much more useful for catching other nation-state intelligence spies at wor…

What do they use? Trusted couriers?

"Terrorists use web forums and couriers."

From same source as previous comment: https://twitter.com/thegrugq/status/407662098093580288

Re: DissidentX – Censorship resistance tool by Bram Cohen

#40

Post by bramcohen »

sillysaurus2 wrote: post #21

Judging by the claims and the code, this is a tool created by someone who hasn't read any prior research about steganography. If you trust this, don't be surprised when law enforcement detects that you're using it. I'm surprised to see someone of Bram Cohen's caliber releasing something like this. No one has any business coding security tools unless they've taken time to read forensics whitepapers to look for reasons…

This is a framework for steganographic schemes, not a specific steganographic scheme. The specific ones thrown in are just for demonstration purposes. The versatility of this approach is a major step forward in defeating statistical detection schemes. You of course don't know this, because you haven't read through the page and figured out what the code does.
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