Remote control for virtualized desktops <\/p>\n
While the application of quantum computers to cracking cryptography is still, for now, a futuristic scenario, crypto researchers are already taking that future seriously. <\/p>\n
It came as a surprise to Vulture South to find that in October of this year, researchers at GCHQ's information security arm the CESG abandoned work on a security primitive because they discovered a quantum attack against it. <\/p>\n
Presented to the ETSI here, with the full paper here, the documents outline the birth and death of a primitive the CESG called Soliloquy. <\/p>\n
Primitives are building blocks in the dizzyingly-complex business of assembling a cryptosystem: individual modules that are expected to be very well-characterised before they're accepted into security standards (and, in the case of crypto like RC4, dropped when they're no longer safe). <\/p>\n
Given that improving computer power is one of the ways a primitive can be broken, there's a constant background research effort into both creating the primitives of the future, and testing them before they're adopted and that's where Soliloquy comes in. <\/p>\n
As the CESG paper states, Soliloquy was first proposed in 2007 as a cyclic-lattice key exchange primitive supporting between 3,000 and 10,000 bits for the public key. Between 2010 and 2013 presumably as part of their effort to case-harden the primitive before releasing it into the wild the boffins (Peter Campbell, Michael Groves and Dan Shepherd) developed what they call a reasonably efficient quantum attack on the primitive, and as a result, they cancelled the project. <\/p>\n
The quantum algorithm they describe would work by creating a quantum fingerprint of the lattice Soliloquy creates; discreteise and bound the control space needed; and run a quantum Fourier transform over that control space, iteratively to get lots of samples approximating the lattice. <\/p>\n
That's where the quantum attack is complete: after that, the samples would get fed into a classical lattice-based algorithm to recover the values you want in other words, the key. <\/p>\n
The main challenge, the authors write, is to define to define a suitable quantum fingerprinter that could handle the control space. <\/p>\n
<\/p>\n