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Cryptography [PART I]

Name: Cryptography 2012-10-16 22:36

Cryptography

Name: Anonymous 2012-10-20 3:55

>>38

But there is a problem. When you encode your information into the bible, you will modify it slightly and the differences encode your message. However, an ease dropper will recognize the writing as the bible. All they have to do is correctly guess the exact copy you used and do a diff to get an encoding of your message. The message may still be encrypted, but if this is in the right context, this is enough to provoke suspicion.

If you are going to transmit a large amount of data using stenography this way, you should use a large original data set that is not publicly available so that the ease dropper cannot get a copy of the original to compare it to.

Name: Anonymous 2012-10-20 3:58

>>41
You dont encode, you just pick matching page.

Name: Anonymous 2012-10-20 4:01

>>42

that too is an encoding. The page number is the encoded value and this value can be determined by indexing the pages of the bible and performing a look up.

As before, it isn't a big deal if the encoded values are encrypted. But if the encoding is noticeable then the stenography didn't work.

Name: Anonymous 2012-10-20 4:06

>>43
not a page number, but the content of the page (i.e. number of comas/whitespaces)

Name: Anonymous 2012-10-20 8:32

ease dropper
What.

Name: Anonymous 2012-10-20 8:43

>>45
Here's a nice Javascript quiz for you to try.
http://a4esl.org/q/j/ck/ed-punct01.html

Name: Anonymous 2012-10-20 16:27

>>34
But encrypted data within steganography takes more analysis to detect.
Well, it would be pretty silly to use steganography not in conjunction with an encryption scheme.  Now I think it should be possible to steganographically hide a public key encrypted message as long as there are no visible unencrypted headers (and that the public key structures have uniform distribution in all their bits, which I don't think holds for all ciphers although it might be possible to adapt for some).  But yeah, for decryption, one would have to try every steg encoding scheme against every private key in storage.

Name: Anonymous 2012-10-21 1:10

>>41
ease dropper
I laughed so much I almost fell off my pedal stool.

Name: Anonymous 2012-10-21 6:36

"Haruhi-chan, have you read about public key cryptography?"
"Cryptography? Uh..."
Wait a minute. What does cryptography have to deal with Nagato? I thought you were her therapist and this would be more psychobabble. Just what is going on here?
"Secret messages? Encryption, internet security, does that give you a hint?"
"I uh eh..."

Asahina-san made a hand gesture calling Haruhi's attention. "Earth to Haruhi, Earth to Haruhi, do you read me, Haruhi?"
"Eh? Oh, sorry! It's just that this government business caught me off guard..."
Asahina-sensei chuckled. "It's understandable. Kyon-kun almost threw up the first time I met him and told him about me. So, Haruhi-chan, have you thought about the answer?"
"Uh, what was the question?"
"Public key cryptography."
"Hmmm let me see... I remember. It was about prime numbers."
"That's right. If you have two prime numbers, N1, and N2, by multiplying them you obtain a bigger number. If someone, let's say, Alice, wants to send a message to Bob, the only thing Bob needs to give Alice is the multiplied number N1*N2 = M, to encrypt her message. Bob can decrypt the message because he knows what N1 and N2 are."

Wait a minute... prime numbers, multiplying, what? I'm not very good at math, someone explain this to me.
"You seem confused, Kyon-kun. But I'll let Haruhi explain to you later. Or... you could look it up in Google."
Haruhi stared at me with an annoyed look. What? I'm still studying in High school, how was I supposed to know that?
"Anyway, if Alice wanted to obtain N1 and N2 from M to decrypt a message sent to Bob, she would need to run a supercomputer for years trying to guess what N1 and N2 are. So that's the basis for public key cryptography."
Haruhi nodded quickly, while I was just following her. Asahina-sensei continued with her speech.
"Do you know what would happen if somehow, this powerful encryption could be broken with a super-incredible computer?"
"Yes..." said Haruhi, holding her chin. "It would mean... that, all the internet would..."
Asahina-sensei finished explaining. "Nothing would be secure anymore. Private conversations, financial transactions, intelligence secrets, confidential documents, nothing would be safe. Nothing. Now, you must be wondering what this has to do with Nagato-san, right?"

Name: Anonymous 2012-10-21 11:42

Haruhi-``chan''? Who the fuck would call her like that?

Name: Anonymous 2012-10-21 11:54

>>50
You've never watched 涼宮ハルヒちゃんの憂鬱?

Name: Anonymous 2012-10-21 12:28

>>51
I did, but I don't remember anyone calling her like that.

Name: Anonymous 2012-10-21 15:56

>>48
pedal stool
Have you been shitting on your bicycle again?

Name: Anonymous 2012-10-21 17:25

>>53
Everybody sing along now...
The S&M man,
The S&M man,
The S&M man because he mixes it with love,
And makes the hurtin’ feel good.
The hurtin’ feel good.

Name: Anonymous 2012-10-21 19:50

New /prog/ challenge: write a secure and undetectable public key steganography system in less than 1000 lines in your favourite language.  You are allowed to use OpenSSL.

Name: Anonymous 2012-10-21 20:06

>>55
Nice dubs NSA-kun.

Name: Anonymous 2012-10-21 20:10

>>55
I'm too dumb for that.

Name: Anonymous 2012-10-21 20:14

>>55
Forget it, it's NP-complete.

Name: Anonymous 2012-10-21 20:51

>>56
Why the hell would the NSA encourage or even suggest the creation of such software?

Name: Anonymous 2012-10-21 20:56

>>59
To see how the enemy thinks.

Name: Anonymous 2012-10-22 1:15

>>61GET!

Name: Anonymous 2012-10-22 1:55

>>60
I don't think public development of public key crypto+steganography is really in their insane mass surveillance interests.

Name: Anonymous 2012-10-22 14:11

one-time pad master race reporting in

Name: Anonymous 2012-10-22 15:48

>>63
doesn't work for public key, fagstorm

Name: Anonymous 2012-10-22 16:09

Is it true that if you extend the Enigma machine with two more rotors, it remains secure even today?

Name: Anonymous 2012-10-22 16:15

I steganographically store messages on /prog/ by selectively claiming certain strategic post numbers.

Name: Anonymous 2012-10-22 16:20

I steganographically store messages on /prog/ by inserting zero-width spaces.

Name: Anonymous 2012-10-22 19:09

I steganographically store messages on /prog/ by exploiting Unicode homoglyphs.

Name: Anonymous 2012-10-22 21:18

>>55
Does it have to be inside an image, or can it be audio or video?

Name: Anonymous 2012-10-22 21:59

I steganographically store messages on /prog/ by plunging  homosexuals.

Name: Anonymous 2012-10-22 22:26

I steganographically store messages on /prog/ by posting sequences of mutated sentences.

Name: Anonymous 2012-10-22 23:37

>>65-67,71
Does this explain the Jew spammer?

Name: Anonymous 2012-10-22 23:45

>>72
Considering the excruciatingly low signal-to-raise ratio, I'd say yes.

Name: Anonymous 2012-10-23 13:09

So, any cool free steganalysis tools or algorithm descriptions?

Name: Anonymous 2012-10-23 13:18

>>66
I get it now! Dubs are the alphabet of an encrypted message that takes months to emit.

Name: Anonymous 2012-10-23 13:28

>>74
Here's an idea: correlate (some of) the higher 7 bits against the lower one in unaltered signal, and notice the patterns that occur.

Name: VIPPER 2012-10-23 13:50

Fuck dubs. Eat shit dubs spammer.

Name: Anonymous 2012-10-23 14:06

>>75
Yes, and the message he is sending out is check my delicious doubles.

Name: Anonymous 2012-10-24 0:00

Name: Anonymous 2012-10-24 4:25

>>79
2012-10-24 00:00
Whoa, binary decuples for the date and decimal quadruples for the time.

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