[Cryptography] Steganography and bringing encryption to a piece of paper

[Sampo Syreeni]

On 2014-07-18, Christian Huitema wrote:

>> Let's imagine that there is a person who is a conlang hobbyist and 
>> has a diary which he keeps in an entirely made-up language.
>
> The made up language works for a personal diary, but it would not have 
> solved the problem for my mother (and mostly my grandfather). They 
> needed to send messages that would not be flagged by the censors. A 
> language that censors did not understand was sure to draw the 
> attention of the Gestapo!

I actually believe Feynman said pretty much the same thing about his 
code(s) with his wife, from his time at Los Alamos. And of course this 
is how it very well works if you happen to do your steganography right, 
*plus* your adversary also happens to know that you might be doing so 
(sorry about the long quote, but it's very much topical):

             So, very delicately amongst all these liberal-minded
             scientific guys, we finally got the censorship set up, with
             many rules. We were allowed to comment on the character of
             the administration if we wanted to, so we could write our
             senator and tell him we don't like the way things are run,
             and things like that. They said they would notify us if
             there were any difficulties.

             So it was all set up, and here comes the first day for
             censorship: Telephone! Briiing!

             Me: "What?"

             "Please come down.

             I come down.

             "What's this?"

             "It's a letter from my father."

             "Well, what is it?"

             There's lined paper, and there's these lines going out with
             dots - four dots under, one dot above, two dots under, one
             dot above,
             dot under dot...

             "What's that?"

             I said, “It's a code."

             They said, “ Yah, it's a code, but what does it say?"

             I said, “I don't know what it says."

             They said, “Well, what's the key to the code? How do you
             decipher it?"

             I said, “Well, I don't know."

             Then they said, “What's this?"

             I said, “It's a letter from my wife - it says TJXYWZ TWIX3."

             "What's that?"

             I said, “Another code."

             "What's the key to it?"

             "I don't know."

             They said, “You're receiving codes, and you don't know the
             key?"

             I said, “Precisely. I have a game. I challenge them to send
             me a code that I can't decipher, see? So they're making up
             codes at the other end, and they're sending them in, and
             they're not going to tell me what the key is."

             Now one of the rules of the censorship was that they aren't
             going to disturb anything that you would ordinarily do, in
             the mail. So they said, “Well, you're going to have to tell
             them please to send the key in with the code."

             I said, “I don't want to see the key!"

             They said, “ Well, all right, we'll take the key out."

             So we had that arrangement. OK? All right. Next day I get a
             letter from my wife that says, “It's very difficult writing
             because I feel that the _____ is looking over my shoulder."
             And where the word was, there is a splotch made with ink
             eradicator.

             So I went down to the bureau, and I said, “You're not
             supposed to touch the incoming mail if you don't like it.
             You can look at it, but you're not supposed to take
             anything out."

             They said, “Don't be ridiculous. Do you think that's the way
             censors work - with ink eradicator? They cut things out with
             scissors."

             I said OK. So I wrote a letter back to my wife and said,
             “Did you use ink eradicator in your letter?" She writes
             back, “No, I  didn't use ink eradicator in my letter, it
             must have been the____ and there's a hole cut out of the
             paper,

             So I went back to the major who was supposed to be in charge
             of all this and complained. You know, this took a little
             time, but I felt I was sort of the representative to get
             the thing straightened out. The major tried to explain to
             me that these people who were the censors had been taught
             how to do it, but they didn't understand this new way that
             we had to be so delicate about.

             So, anyway, he said, “What's the matter, don't you think I
             have good will?"

             I said, “Yes, you have perfectly good will but I don't think
             you have power." Because, you see, he had already been on
             the job three or four days.

             He said, “We'll see about that!" He grabs the telephone, and
             everything is straightened out. No more is the letter cut.

             However, there were a number of other difficulties. For
             example, one day I got a letter from my wife and a note
             from the censor that said, “There was a code enclosed
             without the key, and so we removed it."

             So when I went to see my wife in Albuquerque that day, she
             said, “Well, where's all the stuff?"

             I said, “What stuff?"

             She said, “Litharge, glycerine, hot dogs, laundry.”

             I said, “Wait a minute - that was a list?"

             She said, “Yes."

             "That was a code, “ I said.”They thought it was a code -
             litharge, glycerine, etc." (She wanted litharge and
             glycerine to make a cement to fix an onyx box.)

             All this went on in the first few weeks before we got each
             other straightened out. Anyway, [...]

Most definitely, I've always envied Feynman for his wife. You don't just 
play such steganographic games with any wife, you see.
-- 
Sampo Syreeni, aka decoy - decoy at iki.fi, http://decoy.iki.fi/front
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