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StegFS: A Security File System With Plausible Deniability.

By techt in News
Tue Apr 04, 2000 at 12:36:46 AM EST
Tags: Technology (all tags)

Andrew D. McDonald and Markus G. Kuhn (of Season7 fame) have released a paper in PDF entitled StegFS: A Steganographic File System for Linux which describes a novel file system with effective data hiding abilities. McDonald has written an implementation as a Linux 2.2 kernel patch which can be found on the StegFS WWW Site along with other information.

Even if you aren't interested in a data hiding file system, both Kuhn's and McDonald's pages have a wealth of information between them which many may fine enlightening or of value. For this reason alone, one should check out their pages.


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Related Links
o Andrew D. McDonald
o Markus G. Kuhn
o Season7
o StegFS: A Steganographic File System for Linux
o StegFS WWW Site
o Also by techt

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StegFS: A Security File System With Plausible Deniability. | 13 comments (13 topical, editorial, 0 hidden)
It's about Linux.... (1.00 / 1) (#2)
by teach1 on Mon Apr 03, 2000 at 10:18:40 PM EST

teach1 voted 1 on this story.

It's about Linux.

It's sytems like these that will ev... (3.00 / 1) (#1)
by rusty on Mon Apr 03, 2000 at 10:19:02 PM EST

rusty voted 1 on this story.

It's sytems like these that will eventually force legislators to realize that you simply cannot legislate encryption out of existence, without becoming a totalitarian "guilty until proven innocent" state. Ok, that's my freedom rant-let for the day. :-)

Not the real rusty

Hooray for steganography. Really c... (1.00 / 1) (#4)
by fluffy grue on Mon Apr 03, 2000 at 10:22:23 PM EST

fluffy grue voted 1 on this story.

Hooray for steganography. Really cool stuff. :)
"Is not a quine" is not a quine.
I have a master's degree in science!

[ Hug Your Trikuare ]

Anything used to subvert a knowledg... (2.00 / 1) (#5)
by nascent on Mon Apr 03, 2000 at 10:33:42 PM EST

nascent voted 1 on this story.

Anything used to subvert a knowledge lockdown or employ a stealth info-transfer-method, gets my vote in spades.

ganked from their README: ... (4.00 / 1) (#6)
by confidential on Mon Apr 03, 2000 at 11:50:45 PM EST

confidential voted 1 on this story.

ganked from their README:

To give a brief overview:
When a hidden level is 'closed' we cannot see the files stored there - the kernel cannot see the files there, no-one can. If we write files to a lower level then we might overwrite these hidden files. To reduce the risk of losing files we, therefore, write several copies of each inode and data block. If we overwrite some of the copies, we hopefully have others left to use instead. However, if all copies are overwritten then that data is lost. This is one of the prices to pay for the steganography.

Because we write multiple copies of blocks you should also remember that this takes up more space.

sounds... interesting to say the least, but it also sounds like you'd need a huge disk for it. if it copies everything you do 3 or 4 times (maybe more) you would need 20 gigs of space to just get 5 gigs of data. When you absolutly must have security, its a nice idea though. *shrug* oh well... anyone have any opinions?

So you need a huge disk (none / 0) (#13)
by marlowe on Thu Apr 06, 2000 at 06:15:45 PM EST

Isn't enormous overhead implicit in any successful steganography scheme?

--- I will insist on my right to question ---

-- The Americans are the Jews of the 21st century. Only we won't go as quietly to the gas chambers. --
[ Parent ]
This is old news, but I'm voting fo... (3.00 / 1) (#3)
by Nyarlathotep on Tue Apr 04, 2000 at 12:33:37 AM EST

Nyarlathotep voted 1 on this story.

This is old news, but I'm voting for this because it's very importetn that people know about StegFS. The papers really are very good. People with any interest in cryptography should read them. I would really like to see portable devices like hand helds and cell phones implement this. Example: you memory cost would go up by a factor of 16 but you would have stynography layers which the cops could not prove existed. Note: You would not need a system like this in a smart card since no smart cards are really secure. Really secure requires your public key and stuff never ever leaving the smartcard under any sircumstance, i.e. must have a built keyboard to type your passwrod on and a built in CPU for decryption, none of this "I'll type my pib into the merchents card scanner" bullshit.
Campus Crusade for Cthulhu -- it found me!

Re: This is old news, but I'm voting fo... (none / 0) (#7)
by End on Tue Apr 04, 2000 at 10:15:04 AM EST

You mean private key, right? The public key is useless if it is never distributed. Of course you are then right, the private key should never be accessed by a host machine. -JD

[ Parent ]

cryptoanalys (3.00 / 1) (#8)
by henrik on Tue Apr 04, 2000 at 03:06:31 PM EST

Suppose the NSA (or any other organization of the same kind) wanted your secret cookie recepies stored in your stenographic FS. You think they'll be content with you saying that there isn't anything more in there? You can be pretty sure the NSA prefers breaking fingers to breaking codes. Even if you give them some of the levels i'm sure they're good enough to spot the lie and keep the thumbscrews out in plain view until they're sure nothing else is there. (there's something about "There's nothing else in there, i swear" that just sounds inprobable).

Acctually, How many of us have stuff the NSA would be interested in? :)
I've discovered that i don't really care about privacy issues - if doubleclick can find out what i'm interested in, and keep putting swiss chocklate banners on every page i visit, why not?

BTW - i've written an essay about the evolution of cryptography and it's use in war times, a gentle introduction into the depths of cryptography, and what uses it has in the real world. The field of cryptogaphy wasn't born with 128 bit IDEA and RSA. Would anyone like to see it here? It's not really computer related, but it's tech and it's from the trenches :)


Akademiska Intresseklubben antecknar!

Crypto Essay (none / 0) (#9)
by rusty on Tue Apr 04, 2000 at 03:43:17 PM EST

Absolutely we'd like to see it here! :-)

Not the real rusty
[ Parent ]
crypto essay (none / 0) (#10)
by Anonymous Hero on Tue Apr 04, 2000 at 05:04:21 PM EST

ok, so long as you don't go on about caesar ciphers or how the romans used to shave slave's heads, write a message on it, wait for the hair to grow back, and then send the message, tho truly that is more steganography

[ Parent ]
Re: crypto essay (none / 0) (#12)
by rusty on Tue Apr 04, 2000 at 07:07:59 PM EST

Wouldn't it only be stganography if they, for example, colored certain hairs different colors, and encoded the message that way. I.e. hiding the meaningful hairs within a mass of non-meaningful hairs, in such a way that you'd need a key or pattern to decode.

Not the real rusty
[ Parent ]
The Arthur Norman Connection (1.00 / 1) (#11)
by Anonymous Hero on Tue Apr 04, 2000 at 05:29:23 PM EST

Hmm, it isn't a coincidence but Andrew McDonald (StegFS guy above), Simon Tatham (author of PuTTY) and Nicko van Someren (founder of nCipher) are all members of the Arthur Norman Fan Club. Arthur Norman should be an inspiration to us all! :-)

Visit the ACN Fan Club for light compsci humour.

StegFS: A Security File System With Plausible Deniability. | 13 comments (13 topical, 0 editorial, 0 hidden)
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