The only long-term way to hide data is not to use public networks for communication. Eventually, quantum computers should be able to eat though any of today's crypto. It will be interesting to see what happens when everyone running for public office has their entire life on display.
I reached out to the cryptographic community for any insight into Molly’s question about why the NSA insists that TOP SECRET material be encrypted using 256-bit keys. The answer came from Steven Bellovin of Columbia University:
@jpgoldberg @marshray Just heard that during the AES competition, NSA said in the open meetings it was for defense against quantum computing
Quantum computers, if they are every made practical, will be able to do amazing things. They will certainly change how we design cryptographic systems. It’s not that quantum computers will be faster or more powerful. Indeed, in some very important respects they will be less powerful than current computers. But there are some things that they will be able to do in less “time”. I put “time” in scare quotes because it has a different meaning in this context from the ordinary use of the word. Oh, what a big difference it is. In this context it means the number of distinct steps an algorithm must take in performing some computation.
Searching through 2128 keys (on a classical, non-quantum, computer) takes a number of steps that is proportional to 2128. But for a quantum computer it takes a number of steps proportional to the square root of that number, 264. If a quantum computer is ever built capable of performing that task, we don’t know how the actual speed of each individual step will compare to those of current computers, but the NSA is taking no chances. Something with the effective strength of a 64-bit key isn’t strong enough. A 256-bit key against a quantum brute force attack would have the effective strength of a 128 bit key against a classical brute force attack.
I very much doubt that we will see a quantum computer actually capable of handing such things within the next thirty years. But if the past is any guide, my predictions about the future should be taken with a large grain of salt.
Thanks, that's a good read. I'm interested to see how effective it will be. I'm certainly not saying we'll be able to break non-deterministic crypto, but there's a lot we should be able to do that's out of our reach right now.
We're so early in development that we don't know how quickly we'll be able to scale them, but if we solve a few physical problems, we're looking the ability to scale up resources for linear costs for exponential rewards. With on-demand cloud pricing models for computing becoming the norm, normal people could do some pretty amazing things. It's hard to predict how quickly this will come, but it will definitely come eventually.
> Eventually, quantum computers should be able to eat though any of today's crypto.
Not really; see https://en.wikipedia.org/wiki/Post-quantum_cryptography A decent chunk of today's crypto is either immune or only weakened a little bit (for example, Bitcoin is mostly immune although the SHA hashes are a little weakened and so hypothetically miners might some day move to quantum computers using Shor's algorithm to mine for matches).
Oh absolutely, but I don't know of any one-time-pad schemes that normal people use to encrypt their online activities. That means moving information outside the public network before sending messages over it.
If we can get entangled particles between parties ahead of time to exchange keys, we can do all sorts of fun things.
