Tangled_mind
stranger
Reged: 12/10/04
Posts: 2
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In a post in this sections it says a rotating clear text could not be used in reality as it would make recover of the message impossible to the recipient even with the correct key.
Is it not possible to have a public key for the clear text aswell to undo the rotation process? For instance if the clear text moved on a basic shift 1 basis every hour then when the legitimate recipient would recieve the message, decrypt it with the public key and then back track the process either as it was decrypting or maually if it was a short message ?
obviously this would only slow down a human decrypter if a simple encryption like shift1 was used but obviously in practise a more complicated algorithm would be used, although even a simple one would keep a computer going round in circles 
can anyone see any pitfalls or problems with the above? only an idea i had while in the pub so it does have some beer inspiration 
Also can anyone point me in the direction of some books along the same lines as dan browns?
cheers
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Dave_Howe
stranger
Reged: 12/13/04
Posts: 4
Loc: Manchester England
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It either violates the premise in the book (that only a standard-sized key was used) by introducing additional key bits, or requires reuse of the key. TBH though, no cryptosystem is safe against a brute force attack if the machine can exhaust the keyspace and knows in advance what the plaintext will be. the latter part is important. relying on "guessing" that you have found the plaintext on the fact that it sorta looks like english words doesn't work if the file isn't english words - a zipfile for example.
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Dachande
stranger
Reged: 02/05/05
Posts: 2
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Rotating Cleartext is the wrong name really for what is described. What is really happening is multi-layered encryption. The text is encrypted and then encrypted again. This way if the brute force assault does break the first code there is no way it could know it has as the second layer of encrpytion would look like random text.
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8549176320abc
enthusiast
Reged: 05/02/05
Posts: 219
Loc: UK
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So you encrypt once with a standard algorithm the cypher text from say a simple ceaser box or vigenere cypher. The brute force atack has to go through two stages doubling the complexity and rendering the atempt useless.
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Governments offer us safety for our freedom. It is by seeing this safety as false that we are freed.
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Kevin
stranger
Reged: 08/01/05
Posts: 2
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If the rotating clear text function uses a "time-variant" as Dan Brown mentioned, isn't it possible to prevent the cleartext from shifting by disabling the computer clock? Just a thought...
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Michelangelo
journeyman
Reged: 08/22/05
Posts: 66
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Maybe. I am not sure.
You use to be able to do that with the W32.Blaster Worm virus.
You set you computer clock back and year or so and it would stop 
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XZantoth
stranger
Reged: 09/04/05
Posts: 2
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Hey all.... this is my first post (haven't finished Digital fortress yet) but this rotating clear text has me confused...
There can't be a function that shifts the clear text because there would have to be a function that executes after the message is decrypted. You're taking a text file and creating another text file.... it's not an executable. As for a double encryption, I can see that... it would increase the complexity exponentially.
Let me know what you think.
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Michelangelo
journeyman
Reged: 08/22/05
Posts: 66
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I suppose but files can change formats from what they seem to be. Like you can rename a txt file to a dll file and when u try open it it wont then you rename it to a txt file and open it so it could be the same with the text files and exes ?
Just thinking
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Arras
enthusiast
Reged: 05/24/04
Posts: 263
Loc: B.C., Canada
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This issue was discussed ad nauseum in an earlier thread in this forum. You may wish to read what others have already said, if you wish to add to the discussion, otherwise we'll just be repeating ourselves endlessly. See Rotating Cleartext and other Plotholes.
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walid97
stranger
Reged: 12/31/05
Posts: 7
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That's right..
I don't think it is possible !
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Nasim1
stranger
Reged: 08/21/07
Posts: 1
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Well I think DF is breakable in the first place! The only thing to be done is to run the TRANSLTR again on every decrypted text it gets for each passkey (run the machine once with the “guessed” passkey and then run the deciphering code again on the resultant text that comes out of the first run), …to see if it will break to something meaningful.
So instead of running the code once, you have to run the deciphering code once to get a gibberish text, and then run the code AGAIN on the gibberish text to see if it results to something meaningful.
It will take a lot longer of course, but if a machine with a million processors can break a 64 digit coded text in an hour, I’m sure a machine with a billion processors can break DF in less than a day.
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