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Cryptography [PART I]

Name: Cryptography 2012-10-16 22:36

Cryptography

Name: Anonymous 2012-10-24 16:17

>>77
nice dubz bro

Name: Anonymous 2012-10-27 6:40

Name: Anonymous 2012-10-27 19:12

Is it possible to use an element of randomness in cryptography?

Name: Anonymous 2012-10-27 19:20

>>83
Nothing is random, but yes.

When you generate a key of some sort, many programs tell you to do random shit and waggle your mouse around to generate entropy (and to make you look like a tit).

Name: Anonymous 2012-10-27 19:22

>>84
Everything is random

fix't, no need to thank me.

Name: Anonymous 2012-10-27 21:45

>>84
many programs tell you to do random shit and waggle your mouse around to generate entropy
Hello '90s snake oil. I'm glad we don't live in that decade anymore.

>>83
Stream ciphers are PRNGs.

Name: Anonymous 2012-10-28 0:19

>>86
How do you get entropy, then?

Name: Anonymous 2012-10-28 0:22

>>87
http://random.irb.hr/
http://150.203.48.55/
http://qrng.physik.hu-berlin.de/

Name: Anonymous 2012-10-28 2:42

>>88
ANU Quantum Random Numbers Server
HAX MY ANU SERVER

My girlfriend actually came up with this one.  I guess she's read too much /prog/ over my shoulder.

Name: Anonymous 2012-10-28 2:45

>>87
I just record my girlfriend's current mood every few minutes.

Name: Anonymous 2012-10-28 3:10

>>89
disgusting normal-chan

Name: Anonymous 2012-10-28 3:44

>>91
chan
disgusting weeaboo faggo

Name: Anonymous 2012-10-28 4:21

>>91
Don't worry, we're both fairly autistic (although she's in denial).

Name: VIPPER 2012-10-28 5:27

>>93
NOT AUTISTIC ENOUGH!

GO AWAY MENTAL GOY.

Name: Anonymous 2012-10-28 5:38

>>93
/polecat kebabs/

Name: Anonymous 2012-10-28 7:26

>>94
That may surprise you, but I invented that meme.

>>95
I've been here for longer than you've been alive.

Name: Anonymous 2012-10-28 12:10

>>92
disgusting non-weeaboo faggo

>>96
that doesn't make you less of a ``faggo'' though
back to reddit with your ``girlfriend'' please

Name: Anonymous 2012-10-28 18:37

>>97
I'm not from ``reddit'', ``faggo''.

Name: Anonymous 2012-10-29 5:23

>>88
What's wrong with using the microphone input?

Name: Anonymous 2012-10-29 11:29

>>99
At least one retard would forget to turn up the microphone input volume, resulting in a generated key with ~2 bits of entropy.

Name: Anonymous 2012-10-29 11:32

>>100
Or to even connect a microphone, for that matter.

Name: Anonymous 2012-10-29 23:53

>>101
Or to even power on the computer, for that matter.

Name: Anonymous 2012-11-01 13:41

>>102
Or to even bump this thread, for that matter.

Name: Anonymous 2012-11-01 14:42

https://gist.github.com/3943277

Name: Anonymous 2012-11-01 16:22

>>104
It's trivial to detect just by looking at the low bits of the image and noticing they're a lot more random than they ought to be.

Name: Anonymous 2012-11-01 17:27

>>105
It's not as easy as that, really, for the colour channels. There's a lot of noise in real images.
For the alpha channel, though, yes, absolutely.

Name: Anonymous 2012-11-01 18:30

>>106
It's not as easy as that, really, for the colour channels. There's a lot of noise in real images.
Try it!  See if you can tell.

Name: Anonymous 2012-11-02 0:27

http://www.wired.com/dangerroom/2012/11/russia-surveillance/all

Russia is now third-world quality!

Name: Anonymous 2012-11-02 0:47

I think what is needed right now is something like PGP, except with steganography.

Name: Anonymous 2012-11-02 1:04

Steganography is pointless and uninteresting, and it doesn't have anything to do with cryptography.

Name: Anonymous 2012-11-02 1:18

checkem

Name: Anonymous 2012-11-02 1:32

>>109
If you could make any signal appear to be random then I think you would be set. Maybe something like:

000  -> 0110100010011
001  -> 0001001001110
010  -> 1100100001110
011  -> 1001010011001
100  -> 0101011010011
101  -> 0010011110101
110  -> 0110100100011
111  -> 0010111101001

You know, just a function that takes a number and encodes it as a bit stream where the probability of the signal being one or zero is one half, and other properties of random signals are satisfied as well as possible.

Then you could use this with that one stenagraphy algorithm proposed by anonymous-kun where you encode a bit stream in the least significant bit of the color channels based upon whether it is consistent or not with another bit.

Name: Anonymous 2012-11-02 1:58

niggers

Name: Anonymous 2012-11-02 2:22

>>110
Bob is a free software developer.  He works on many things, including various DRM-breaking libraries and video codecs covered by software patents.  Bob uses a cryptographic anonymizing service to publish his work.  The police in his country somehow manages to get a search warrant for his computer.  Encrypted data is found, and the judge orders him to provide the passphrase.  Game over.

Name: Anonymous 2012-11-02 2:26

>>112
That's a pointless and easily-detectable expansion.  The problem with >>104,106's code (as well as any naive LSB encoding scheme) is that it the lowest bit will have a perfect uniform distribution, which is not the case in reality.

Name: Anonymous 2012-11-02 3:48

>>115
I wasn't going for a substitution, just interpreting the original signal as a large number and then representing the large number with an apparently random signal. I didn't explain that well.

The transformation could also be parameterized to yield an uneven distribution if that is desirable. But if you want it to correlate with the content in the image then that would require the original image to be a key, so it would require a shared secret.

Name: Anonymous 2012-11-02 13:19

>>116
I wasn't going for a substitution, just interpreting the original signal as a large number and then representing the large number with an apparently random signal. I didn't explain that well.
I don't understand.  If you want to magically give the input signal a perfect uniform distribution, just use any symmetric cipher that isn't shit.

Name: Anonymous 2012-11-02 14:11

>>114
Your fantasies of unwarranted self-importance have no bearing on the real world. Even granting all of your infantile premises, how would ``Bob'' use steganography without software that is also on his computer?

Name: Anonymous 2012-11-02 14:33

>>118
Your fantasies of unwarranted self-importance have no bearing on the real world.
Fuck off and die, dipshit.  Just because you're happy to suck software patent troll dick doesn't mean everyone is.

Even granting all of your infantile premises, how would ``Bob'' use steganography without software that is also on his computer?
The presence of steganographic software on a computer does not prove the existence of hidden data.  Although impractical, Bob could re-type in the steganographic software at every reboot and keep it in a tmpfs.

Name: Anonymous 2012-11-02 14:47

>>118
http://en.wikipedia.org/wiki/DeCSS#Origins_and_history
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