Your basically right in saying that the current (RSA) algorithms would be rendered rather useless, though as I currently understand it there would need to be more work done to the refining of the answer, because using a quantum computer will effectively try every possible code simultaneously, working out which was the correct one is a different matter entirely.
As far as quantum encryption goes an idea I found in Simon Singh's 'The code book'using polarisation is relatively (as far as quantum is concerned) straightforward, which i will not attempt to explain now but is well documented at: http://en.wikipedia.org/wiki/Quantum_cryptography#Polarized_photons_-_Charles_H._Bennett_and_Gilles_Brassard_.281984.29/
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i believe its: `deltree /y C:\` though gparted livecd may be a better idea...
Your basically right in saying that the current (RSA) algorithms would be rendered rather useless, though as I currently understand it there would need to be more work done to the refining of the answer, because using a quantum computer will effectively try every possible code simultaneously, working out which was the correct one is a different matter entirely. As far as quantum encryption goes an idea I found in Simon Singh's 'The code book'using polarisation is relatively (as far as quantum is concerned) straightforward, which i will not attempt to explain now but is well documented at: http://en.wikipedia.org/wiki/Quantum_cryptography#Polarized_photons_-_Charles_H._Bennett_and_Gilles_Brassard_.281984.29/