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Working the multivariate Coppersmith algorithm

cn flag

I recently studied the multivariate Coppersmith algorithm. Let $f(x)$ be $n$-variate polynomial over $\mathbb{Z}_p$ for some prime $p$. Informally, the multivariate Coppersmith's theorem stated that if the assumption ($*$) holds, then one can solve the multivariate Coppersmith's algorithm in polynomial time in some parameter.

($*$): There exist $n$ algebraic independent polynomials obtained from the LLL algorithm on the matrix $M$, where each row of $M$ is a coefficient vector of a multiple of $f$ or $p$.

Here, for the ease presentations, I assumed that the Coppersmith's criterion always holds.

My questions are: if $n$ is large, (e.g., n = 50 or 100), then, can we find $n$ algebraically independent polynomials from $M$? I think it is always impossible since $n$ is too large, but I could not find any paper that deals with such a large $n$.

** I know that the complexity of finding multivariate polynomials takes a huge cost, but in this thread, I only focus on the existence of $n$ algebraically independent polynomials.

Is there any example for using the multivariate Coppersmith's algorithm for $n>5$? I only found the applications of the multivariate Coppersmith's algorithm on polynomials in $n = 2$ or $3$. Thus, I'm somewhat confused that the Coppersmith's algorithm can actually work if $n>5$. Indeed, I do not know how to obtain $n$ algebraically independent polynomials from a single polynomial $f$.

Moreover, how to guarantee the assumption ($*$) for some $n = 10,20,30$? I think that it is hard to implement such cases in personal computers. In this case, how to convince that the algorithm succeed?

Turbo avatar
ru flag
where did you find for $n=3$?
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