ISIS solver

This is an implementation of the following algorithm which solves the subset-sum problem in the group $\mathbb{Z}_q^n$ for $q=2^l$ and $m=(2n+1)^l$ in time $O(n^2m)=2^{O(\log n\log q)}$, with aborting probability $\mathrm{negl}(n)$ if $A$ and $y$ are randomly chosen. This algorithm uses $m-nl$ random bits, and is randomness recoverable.

The procedure $P1$ is a deterministic procedure that extends a full row-rank matrix $A\in\mathbb{Z}_2^{r\times m}$ to another full row-rank matrix $\tilde{A}\in\mathbb{Z}_2^{n\times m}$ by adding $n-r$ rows of unit vectors to $A$.

The algorithm is revised from the paper [CH25].