arXiv:1611.06999quant-ph
An Efficient Quantum Algorithm for a Variant of the Closest Lattice-Vector Problem
Abstract
The Systematic Normal Form (SysNF) is a canonical form of lattices introduced in [Eldar,Shor '16], in which the basis entries satisfy a certain co-primality condition. Using a "smooth" analysis of lattices by SysNF lattices we design a quantum algorithm that can efficiently solve the following variant of the bounded-distance-decoding problem: given a lattice L, a vector v, and numbers b = λ_1(L)/n^{17}, a = λ_1(L)/n^{13} decide if v's distance from L is in the range [a/2, a] or at most b, where λ_1(L) is the length of L's shortest non-zero vector. Improving these parameters to a = b = λ_1(L)/\sqrt{n} would invalidate one of the security assumptions of the Learning-with-Errors (LWE) cryptosystem against quantum attacks.
Thats a good paper. I thought about it awhile and would retract my remarks of it being expensive and replace it with being expensive or risky. Also there's the problem of "what is the definition of post quantum" where a lot of people call 1995 or so after Shor "PQ", and maybe…
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