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diff --git a/slides/2022-ct-days/src/ctor.tex b/slides/2022-ct-days/src/ctor.tex new file mode 100644 index 0000000..f7ed6c3 --- /dev/null +++ b/slides/2022-ct-days/src/ctor.tex @@ -0,0 +1,222 @@ +\begin{frame} + \mktitle{Tor crash course} + \centering\includegraphics[width=.8\textwidth]{img/tor/overview} + \footnotetext[1]{\tiny{Credit: figure created by Tobias Pulls}} + \footnotetext[2]{\tiny{Design: \burl{https://murdoch.is/papers/tor14design.pdf}}} +\end{frame} + +\begin{frame} + \mktitle{Tor Browser} + \begin{columns} + \begin{column}{0.6\textwidth} + \begin{itemize} + \item Firefox derivative + \item Route all traffic through Tor + \item Prevent user activity on one site from + being linked to activity on another + \item \alert<2->{Do not write any state to disk} + \item ... + \end{itemize} + \end{column} + \begin{column}{0.4\textwidth} + \includegraphics[width=.67\columnwidth]{img/tor/tb} + \end{column} + \end{columns} + \footnotetext[1]{\tiny{Credit: Tom Ritter, see \burl{https://ritter.vg/p/tor-v1.6.pdf}}} + \footnotetext[2]{\tiny{Design: \burl{https://2019.www.torproject.org/projects/torbrowser/design/}}} +\end{frame} + +\begin{frame} + \centering + \includegraphics[width=.75\textwidth]{img/ctor/paper} + \vfill + \includegraphics[width=.75\textwidth]{img/ctor/blog} +\end{frame} + +\begin{frame} + \mktitle{Problem statement} + \begin{columns} + \begin{column}{0.6\textwidth} + \begin{itemize} + \item Tor Browser does not enforce CT + \item Guard against prominent threats + \begin{itemize} + \item DigiNotar style attacks + \item Interception to deanonymize + \end{itemize} + \item Go beyond ``just CT compliance'' + \end{itemize} + \end{column} + \begin{column}{0.4\textwidth} + \centering + \includegraphics[width=.67\columnwidth]{img/tor/tb} + \end{column} + \end{columns} + \vfill\pause + \alert{Attacker in Tor's threat model + controls a CA and two CT logs} +\end{frame} + +\begin{frame} + \mktitle{Incremental deployment} + \begin{enumerate} + \item Catch up with CT compliant browsers + \floatright{\emph{pairs of logs} are trusted blindly} + \item Steps towards decentralized verification + \floatright{\emph{some log} is trusted blindly} + \item Fully decentralized verification + \floatright{\emph{no log} is trusted blindly} + \end{enumerate} +\end{frame} + +\begin{frame} + \mktitle{Full design} + \centering\includegraphics[height=.5\textheight]{img/ctor/full} + \vfill + \pause + \alert{Security? Difficult to interfere without detection in any phase} +\end{frame} + +\begin{frame} + \mktitle{Why not just...?} + \begin{columns} + \begin{column}{.5\textwidth}\centering + \includegraphics[width=.9\columnwidth]{img/ctor/tb-to-log}\\\vspace{.25cm} + Fetch an inclusion proof + \end{column} + \begin{column}{.5\textwidth}\centering + \includegraphics[width=.77\columnwidth]{img/ctor/tb-to-auditor}\\\vspace{.25cm} + Rely on a centralized party + \end{column} + \end{columns} +\end{frame} + +\begin{frame} + \mktitle{Phase 1: Submission} + \centering\includegraphics[width=.75\textwidth]{img/ctor/phase-1} + \vfill + \begin{columns} + \begin{column}{.2\textwidth}\centering + \end{column} + \begin{column}{.3\textwidth}\centering + \alert{1.} Probabilistic submit + \end{column} + \begin{column}{.3\textwidth}\centering + \alert{2.} Random CTR + \end{column} + \begin{column}{.2\textwidth}\centering + \end{column} + \end{columns} + \pause + + \vfill + \alert{Best attack: quickly take control over Tor Browser} +\end{frame} + +\begin{frame} + \mktitle{Phase 2: Buffering} + \begin{columns} + \begin{column}{.5\textwidth} + \begin{enumerate} + \item Buffer until logging is required + \item Add a random delay to leak less + \item Cache audited SFOs to leak less + \end{enumerate} + \end{column} + \begin{column}{.5\textwidth} + \centering + \includegraphics[width=.45\columnwidth]{img/ctor/phase-2} + \end{column} + \end{columns} + \pause + + \vfill\centering + \alert{Best attack: network-wide flush} +\end{frame} + +\begin{frame} + \mktitle{Phase 3: Auditing} + \begin{columns} + \begin{column}{.4\textwidth} + \begin{enumerate} + \item Fetch inclusion proof + \item STH from Tor's consensus + \item Collaborate with a watchdog + \begin{itemize} + \item CTR identification + \item ``Tagging'' + \end{itemize} + \end{enumerate} + \end{column} + \begin{column}{.6\textwidth} + \centering + \includegraphics[width=\columnwidth]{img/ctor/phase-3} + \end{column} + \end{columns} + \pause + + \vfill\centering + \alert{Best attack: quickly take control over CTR} +\end{frame} + +\begin{frame} + \mktitle{Phase 4: Reporting} + \centering\includegraphics[width=.4\textwidth]{img/ctor/phase-4} + \vfill + \alert{1.} Report SFO on timeout + \pause + + \vfill + \alert{Best attack: n/a} +\end{frame} + +\begin{frame} + \vfill + \mktitle{This is quite the leap from ``just CT compliance''} +\end{frame} + +\begin{frame} + \mktitle{Incremental design} + \centering\includegraphics[height=.33\textheight]{img/ctor/incremental} + \vfill + \pause + + \alert{Use the log ecosystem against the attacker}\\ +\end{frame} + +\begin{frame} + \vfill + \begin{columns} + \begin{column}{.41\textwidth} + \mktitle{Conclusion} + \begin{itemize} + \item Tor's setting is quite different + \item Delegated audiding is key here + \item Roadmap from start to finnish + \end{itemize} + \end{column} + \begin{column}{.25\textwidth} + \mktitle{Resources} + \begin{itemize} + \item PETS paper\footnotemark[1] + \item PETS talk\footnotemark[2] + \item Tor blog post\footnotemark[3] + \end{itemize} + \end{column} + \begin{column}{.35\textwidth} + \mktitle{Next steps} + \begin{itemize} + \item Torspec proposal(s) + \item Browser implementation + \item Relay implementation + \end{itemize} + \end{column} + \end{columns} + \footnotetext[1]{\burl{https://petsymposium.org/2021/files/papers/issue2/popets-2021-0024.pdf}} + \footnotetext[2]{\burl{https://www.youtube.com/watch?v=f7yDJOd6g3U}} + \footnotetext[3]{\burl{https://blog.torproject.org/tor-certificate-transparency/}} +\end{frame} + +\begin{frame} + \vfill + \mktitle{Halftime} +\end{frame} |