In 2021, Chen, Liu, and Zhandry presented an efficient quantum algorithm for the average-case $\ell_\infty$-Short Integer Solution ($\mathrm{SIS}^\infty$) problem, in a parameter range outside the normal range of cryptographic interest, but still with no known efficient classical algorithm. This was particularly exciting since $\mathrm{SIS}^\infty$ is a simple problem without structure, and their algorithmic techniques were different from those used in prior exponential quantum speedups. We present efficient classical algorithms for all of the $\mathrm{SIS}^\infty$ and (more general) Constrained Integer Solution problems studied in their paper, showing there is no exponential quantum speedup anymore.

翻译：2021年，Chen、Liu与Zhandry针对平均情况下的ℓ∞-短整数解（SIS∞）问题提出了一种高效量子算法，该算法在密码学常规关注范围之外的参数区间内有效，且目前尚无已知的经典高效算法。这一成果尤为引人注目，因为SIS∞是一个无结构的简单问题，其算法技术与此前实现指数级量子加速的方法截然不同。我们在本文中针对该论文研究的所有SIS∞问题及（更广义的）约束整数解问题提出了高效的经典算法，证明这些问题的指数级量子加速优势已不复存在。