Bizarre-ass idea
Okay, so as many of you know I’ve got this, well, *thing* about encryption. Not a thing to the point where I sit around and argue about cryptographically random noise, but I like to ponder. So I had this idea that I’m sure has occured to just about everyone at some point:
Use a DVD as a one-time pad.
OKay, so it’s got weaknesses. But, any given CD/DVD probably has just about every bit string you could ask for. You just send your data as a series of offsets and lengths (probably encrypted using some other method just to make things further obfuscated). The person you’re sending the data to knows which movie or CD the offsets and lengths refer to.
Okay, so it’s not so much useful as silly.
S.
June 30th, 2006 at 5:18 pm
That’s not silly at all. A traditional code was bookcode, where you sent a message containing nothing but groups of numbers, and the other person, knowing what book you were working with, would go look in the appropriate page/paragraph/word number and work out your message. Without knowing what book you’d used, it was unbreakable. A number of historic bookcodes still exist, unbroken, because the people chose obscure books.
I wrote a little bit of steganography that opened a .tiff into a structure that segregated out R, G, & B, and alternately added or subtracted the bitstream of a message from the RGB numbers. Include the picture of your family outing in email to someone, and that person knows that the original is on your webpage, so can diff them and derive the bitstream. A visual inspection of the photograph won’t notice anything.
June 30th, 2006 at 9:23 pm
…they can probably intercept your communications to the other party as to what DVD or CD to use, too.
June 30th, 2006 at 9:27 pm
Not neccesarily. For example, you might think that your digital communications were being monitored but that you were safe when meeting face to face. Or you might think that your communications were not monitored in the past i.e. you could say ‘That movie we went to see in the early 90s, you know the one, we went to Dennys afterwords…’. I can think of lots of scenereos.