Viewing Single Post From: Good Books

Viewing Single Post From: Good Books
Donald	Oct 11 2005, 05:58 PM
Elite member Posts: 454 Group: Trusted Member Member #8 Joined: September 2, 2005	"cows" what about the rotating part? Ask rot13! <This wikipidia article> explains how rot-13 works. A real cryptographer can probably read rot-13 right off the page. So hopefully Dan Brown was talking about something more complicated than merely rotating text. The only provably unbreakable cipher is a one time pad. And perhaps thats what he was talking about since you can "rotate text" as part of it. You collect an amount of random data that MUST be EQUAL to the length of your message. You use that to encrypt your message, The method of encryption could be xor, or Vigenere style, it doesn't make much difference, just as long as you NEVER EVER EVER reuse the key. Now here, I'll prove that it's unbreakable for you. assume my message was SENDHELP. and my random data was AQZDRGIW, lets use vigenere since I'm doing this by hand (and since Vigenere is "rotating text"): (there is a cute little vigenere applet at http://www.uncg.edu/mat/security/vigenere/vigenere.html that will demonstrate the basic idea of a Vigenere for you, or you can read about it on this board) Code: `sendhelp <-original text AQZDRGIW <-true random key SULGYKTK <-encrypted text (Using Caesar shifts)` so, you find the SULGYKTK code and think you can break it, right? The problem is that it could be decrypted to ANYTHING, depending on what random key I decrypt with. for example: Code: `SULGYKTK <-encrypted text GQISLKIH <-decryption key medonald <-plain text SULGYKTK <-encrypted text KTUSOGLR <-decryption key ibrokeit <-plain text` Because EVERY 8 letter combination is possible, and there is no way to tell which decryption is correct unless you have the original random key. One time pads are absolutely uncrackable and secure. And also so impractical as to be almost useless. Donald


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