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NSA Trying To Build Quantum Computer
New submitter sumoinsanity writes "The Washington Post has disclosed that the NSA is trying to build a quantum computer for use in cracking modern encryption. Their work is part of a research project into tackling the toughest equipment, which received $79.7 million in total funding. Another article makes the case that the NSA's quantum computing efforts are both disturbing and reassuring. The reassuring part is that public key infrastructure is still OK when done properly, since the NSA is still working so hard to defeat it. It's also highly unlikely that the NSA has achieved significant progress without outside awareness or help. More disturbing is that it may simply be a matter of time before it fails, and our private messages are out there for all to see."
In *theory* they can match the values of an N bit code in one go where N is the number of quantum bits. In practice it might be another matter but even if not - that simply means you use more bits in your key. Once a quantum computer has used up all its bits it has to revert to working like a standard computer and doing everything serially. So if the quantum computer is N bits and we have a key with N + 32 bits the machine will still have to try 2^32 matches. So as quantum computer registers get larger so will encryption keys. Someone builds a 256 bit quantum computer? Great! So just use a 512 bit key and it'll have to do 2^256 comparisons. ie - it'll be damn slow.
Worse than that - they are wasting that money on a possible task that will actually have little overall impact on security whatsoever.
Post-quantum cryptography has existed for the last 30 years, at least. And to get to the point where it's an issue, what you need is an entity to push towards quantum decryption that you DON'T want to have it (i.e. the NSA, for example).
Then all that happens is we adopt those other schemes faster, spot the holes faster, compensate for them faster, and by the time the NSA can buy a quantum machine of size enough to defeat today's encryption in a reasonable time, we'll have an established standard far beyond it's capabilities and tested for (potentially) decades.
All the NSA has done is forced the entire world to up its game. Compare and contrast to, say, GCHQ who formulated public-key-encryption several years before anyone else had done it, and KEPT IT QUIET (like spy-based agencies are supposed to). They enjoyed years of secure comms, and years of advantage decrypting other secure comms when someone else eventually discovered the exact same mathematics and got famous on it (Diffie and Helman).
Sadly, the modern GCHQ is but a shadow of its former self.