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Factoring appendix
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henrycg committed Nov 2, 2023
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2 changes: 1 addition & 1 deletion lecture-notes.tex
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Expand Up @@ -81,7 +81,7 @@ \part{Conclusions}

\appendix
\part{Appendices}
\include{lectures/app-factor}
\include{lectures/lec06-app}

\backmatter

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3 changes: 2 additions & 1 deletion lectures/app-factor.tex → lectures/lec06-app.tex
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@@ -1,5 +1,5 @@
\chapter{Factoring integers}
\label{sec:fact:bg}
\label{sec:fact}

The problem of integer factorization was central to 20th-century cryptography.
Breaking the one-wayness of the RSA trapdoor one-way function (\cref{chap:rsa}), for example,
Expand All @@ -11,6 +11,7 @@ \chapter{Factoring integers}
Throughout, let $n = \lceil \log_2 N \rceil$ be the bitlength of the number to factor.

\section{Background}
\label{sec:fact:bg}

\paragraph{Trial division.}
We can factor $N$ by trying to divide $N$ by each of the primes of size $\leq \sqrt N$
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3 changes: 3 additions & 0 deletions lectures/lec06.tex
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Expand Up @@ -282,6 +282,9 @@ \subsection{Why should the RSA function be hard to invert?}
(We will say more on this in a moment.)
Since the best algorithms for factoring run in time roughly $2^{\sqrt[3]{\log N}} = 2^{\sqrt[3]{\lambda}}$,
this approach is infeasible at present without knowing the factorization of $N$.
\marginnote{In \cref{sec:fact} we present a factoring algorithm that runs
in sub-exponential time $2^{\sqrt{\log N \log \log N}}$.
}

\item \textbf{Find a root over the integers} and reduce it modulo $N$.\marginnote{Actually,
it suffices to find a root over the rational numbers, but the distinction isn't important here.}
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