Posted on 05/10/2009 5:43:05 PM PDT by A Navy Vet
Odds are, the person with whom you will need to share coded info with is someone you already communicate with on a regular basis. In order to disguise your important messages, you could send unimportant messages or even gibberish on a routine basis. If they have 1,000 messages to sort through in order to find the one, you will gain some time.
That’s not a real solution to your issue, but there is some safety in obscurity.
An encrypted keyword is still encrypted. It still requires the expenditure of computer time to decode and render into a searchable keyword. This has loads of interesting stuff...
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...but until it's decrypted, it's useless gibberish. Furthermore, it's gibberish encrypted with a 2048-bit key. (And in this case, with open source software; where one cannot hide backdoors in the source code!) Unless some old-fashioned detective work is done first, there's no way to know if it's worth decrypting.
Fort Huachuca probably tries but I think they key in on certain word/names only.
But you probably are more conversant about such things than I am.
Just to be on the safe side don’t say anything about that black van in front of your house, they’re trying to blend in.
Actually, if the key is truly random and one-time, it can’t be broken. Think through the scenario. Assume the ciphertext is 1000 characters long, enciphered from 1000 characters of plaintext with a 1000 byte, non repeating key. How will the guys trying to crack the cipher know when they’ve succeeded? By getting a viable plaintext message. But for any 1000 characters of plaintext, there is some 1000 byte key that will produce the ciphertext. If the key is totally random, how are they to know which plaintext solution is the right one?
“Actually, if the key is truly random and one-time, it can’t be broken.”
depends on how long the key is, how long the message is, and how random it is. Also depends on what encryption method is used.
“If the key is totally random, how are they to know which plaintext solution is the right one?”
That is where judgement comes into play. The randomness of the key is only one small factor.
What I’m saying is that if the key is truly random and full length, it will produce random ciphertext. This ciphertext is equally likely (cipherwise) to have come from any clear text passage of the same length, of which there are infinitely many. So there are an infinite number of solutions, and if the key is random, there’s no clue which are more likely than others. You could make an educated guess based on subject matter and what you know about the sender, but remember, ANY 1000 character clear text can produce the cipher text, so it’s pretty much like knowing nothing at all. Now, one could reason in reverse and calculate what the key would have had to have been for any conceivable clear text, and if you think the sender is cryptographically sophisticated, you could throw out the candidates that would need crappy keys to generate the ciphertext, but I don’t see what else you can do.
“What I’m saying is that if the key is truly random and full length, it will produce random ciphertext”
Whats full length? Keys come in increments of 8 with the normal key length being 256. Some software tools will use keys of over 2000.
There is not an infinite number of solutions. It is definately a finite although very high number. With todays computers it is not nearly as difficult as it once was to break a key.
“but I don’t see what else you can do.”
There is a science used to break these codes.
No, no, I’m not talking the type encryption generally done on a PC with 40-bit, or 56-bit, or 128-, or 256-, 1024-, etc, but “one-time pad”, though that can certainly be done on a PC. In that context, “full length” means if you want to encode 1000 characters of clear text, you will need 1000 truly random bytes of keytext. And — you can only use any given bit of keytext once, or you introduce a vulnerability that’s susceptible to statistical analysis, at least if the cryptanalyst knows or suspects that you may have reused keytext. And, yes, I realize I said “infinite” when I shouldn’t have.
A straight character for character substitution is not that secure.
Supposedly a “one time pad” as I’ve described is unbreakable. Now if you’re talking about something that translates one character to a different one according to a rule like “replace each character with the one three letters farther along in the alphabet” or a fixed cipher where each character is replaced by the same other character throughout the message, you’re correct.
“Supposedly a “one time pad” as I’ve described is unbreakable.”
I probably wasn’t clear in my ‘character for character’ description. The weak point is that language has rules. There are only so many words and only so many letters.
Given the desire and enough computer time every cipher is essentially breakable.
I think we’re talking past one another. Check out the term “one time pad” and think through the mathemagical implications of that type cipher and the resulting randomness of the ciphertext.
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