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arXiv · 1201.2739

Division algorithms for the fixed weight subset sum problem

Andrew Shallue
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Abstract

Given positive integers $a_1,..., a_n, t$, the fixed weight subset sum problem is to find a subset of the $a_i$ that sum to $t$, where the subset has a prescribed number of elements. It is this problem that underlies the security of modern knapsack cryptosystems, and solving the problem results directly in a message attack. We present new exponential algorithms that do not rely on lattices, and hence will be applicable when lattice basis reduction algorithms fail. These algorithms rely on a generalization of the notion of splitting system given by Stinson. In particular, if the problem has length $n$ and weight $\ell$ then for constant $k$ a power of two less than $n$ we apply a $k$-set birthday algorithm to the splitting system of the problem. This randomized algorithm has time and space complexity that satisfies $T \cdot S^{\log{k}} = O({n \choose \ell})$ (where the constant depends uniformly on $k$). In addition to using space efficiently, the algorithm is highly parallelizable.

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Andrew Shallue. 2012-01-13. Division algorithms for the fixed weight subset sum problem. https://arxiv.org/abs/1201.2739

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