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RE: Consequences for encryption
By rvd2008 on 6/29/2009 5:55:51 PM , Rating: 3
Quantum computers, when ready, will bring us quantum encryption. If I remember correctly from quantum mechanics, you can not observe a particular state without disturbing the state itself. Quantum encryption is unbreakable AFAIK.

RE: Consequences for encryption
By MrPoletski on 6/30/2009 4:09:50 AM , Rating: 3
Quantum encryption is unbreakable AFAIK.

Then how does the message recipient read the message?

No encryption is unbreakable.

By foolsgambit11 on 6/30/2009 5:47:50 AM , Rating: 5
One-time pads are unbreakable, when created truly randomly, used correctly - i.e., one time - and when the pad is kept secure.

We have to make the distinction between breaking an encryption only by receiving the encoded message, by intercepting the cypher key, by gaining access to the message before it is encoded or after it is decoded, or any other method. Although all of these methods may allow a third party access to the data, I'd only call the first truly 'breaking' the encryption. (Is it really breaking the encryption if you know the key before you start?) The rest are breaking other portions of the security protocol.

Quantum cryptography, as currently envisioned, isn't encryption so much as it is a very secure method of agreeing on and transmitting a one-time pad key for use in encryption. It can theoretically ensure that a suitable one-time pad is delivered without being intercepted to any degree of certainty short of unity desired - true, that isn't completely unbreakable, but it's close enough to certain to keep people from trying. Unfortunately, in practice, since you can't perfectly transmit quantum states without some degradation, photon emitters sometimes emit more than one photon at a time, &c, there are some potential avenues for approach in the error-checking process. Plus, you could always be subjected to a denial-of-service style attack, with somebody constantly snooping just to ensure you can never agree on a key, or just cutting the lines. But none of that is really breaking the encryption.

So, I guess what I'm saying is that there is such a thing as unbreakable encryption, but there isn't such a thing as perfectly safe encryption. You just have to try means other than cracking the encryption. Maybe that's splitting hairs, though.

By foolsgambit11 on 6/30/2009 5:17:07 AM , Rating: 2
As far as you and anybody else knows. The laws of physics as we understand them at the moment make it possible to create an 'unbreakable' cypher by creating a one-time pad style cypher key as long as the message. Unlike traditional one-time pads which require a secure method of delivering the cypher key to the recipient, quantum mechanics allows a key to be agreed on securely by both sender and receiver, while also ensuring nobody can eavesdrop. And this has already been demonstrated at distances of nearly 100 miles over fiber optic line.

'Unbreakable' is in quotes, because there is some information that is possible to be gleaned from the data exchange using current methodology. It is almost certainly not enough to crack most cyphers, but you never know.

Check out the Wikipedia article:

