breaking a code, how is it done and are all codes breakable given that you have the most powerful comp?

[$pade]

Just saw Windtalkers and it got me thinking about codes used for encrypting messages. I am just wondering why is it so hard to come up with a code that is unbreakable. Are there any restrictions that a code has to follow, because else there is an infinite number of ways that you can encode a message and then even the most powerful computer won't be able to break it.

 

[singh]

Originally posted by: $pade
Just saw Windtalkers and it got me thinking about codes used for encrypting messages. I am just wondering why is it so hard to come up with a code that is unbreakable. Are there any restrictions that a code has to follow, because else there is an infinite number of ways that you can encode a message and then even the most powerful computer won't be able to break it.

The main problem is to come up with a scheme such that the enemy gains no advantage even if the message is intercepted in its totality. The crypto systems today rely on two keys for this purpose - the public and the private keys. The public key is visible to all, and the message can be encoded with this key. However, only the person that has the private key can successfully decode the message.

 

[notfred]

Yes, all codes are breakable. Not neccesarily easily, but breakable.

 

[coder1]

All except for the one time stap. That code is mathematically perfect.

 

[jaydee]

RC5 has been pretty succesful in not being cracked.

The best code algorithms are based on factorisation of very large numbers... Like 1000's of digits per number. It's easy to encode it (multipliying large numbers), but extremely difficult (aka impossible) to decode without the key (find all prime factorisation of a 2000 digit number). No way it's happening without a non-deterministic computer (quantum computing).

 

[$pade]

hmm, but still how can you tell that you have cracked the code? I suppose they assume that once they arrive at a message containing words from the dictionary then the code is cracked, but what if the encoded message consists of random words from the english dictionary (or any other obscure language to make it even harder) and each word actually represents a single character. To make it even harder you could have multiple words decode into the same character and then apply multiple other scrambling algorithms. Without knowing the idea behind this code, how can you even program your computer to crack this kind of code?

 

[jaydee]

Simply put, the best codes can't be cracked now if every computer in the world worked on it for 10,000 years. Mabey they do use this method, I'm not sure, but assuming they don't, why make it more complicated when today's methods work great?

 

[jaydee]

As for knowing when the code is cracked... well you just gotta know. If you found a possibility you apply it to the rest of the code and see if it makes sense and gives you the information you need. What would be interesting though is to design a code so that an interceptor could (relatively) easily decode a false message (one that still makes sense), while the real message is more complex and thus secure. You mnow what I mean? This is all rather moot though, because the fact that their ARE unbreakable codes.

 

[Cyberian]

This is quite an enigma.

 

[SloppyB]

My wife bought me The Code Book and it was really good. From the basics to the high end stuff. Also, he put a challenge at the end that has now been broken. The guys that broke it even put out a paper on how they did it...it was almost as good as the book.

/Sloppy

 

[Stojakapimp]

Have you read the book Cryptonomikon (sp?). I think it has something to do with this topic...not sure, but thought I'd give my 2 cents

 

[Kelvrick]

Originally posted by: Stojakapimp
Have you read the book Cryptonomikon (sp?). I think it has something to do with this topic...not sure, but thought I'd give my 2 cents

Isn't that book about... Oh wait, I got that book mixed up with Snow Crash by the same author.

 

[jaydee]

I've read neither of the books, but I think I'll pick up The Code Book, it looks extremely interesting.