From 81b31fcc87d76d314f790196c88233227370fe96 Mon Sep 17 00:00:00 2001 From: Manos Date: Tue, 12 Oct 2021 00:26:35 +0200 Subject: [PATCH] problem: Reviewed lmdk-sel-prob --- text/problem/theotherthing/problem.tex | 26 ++++---------------------- 1 file changed, 4 insertions(+), 22 deletions(-) diff --git a/text/problem/theotherthing/problem.tex b/text/problem/theotherthing/problem.tex index d0cb0dd..cb41446 100644 --- a/text/problem/theotherthing/problem.tex +++ b/text/problem/theotherthing/problem.tex @@ -2,26 +2,8 @@ \label{subsec:lmdk-sel-prob} The problem setting is similar to the one that we described in detail in Section~\ref{subsec:lmdk-set}. -The main difference in this case lies in our threat model where we consider, in addition to the values of the regular and {\thething} events, the {\thething} timestamps $L$ privacy-sensitive as well. +The main difference in this case lies in our threat model where we consider, in addition to the values of the regular and {\thething} events, the {\thething} timestamps $L$ as privacy-sensitive as well. -Given a set of {\thethings} at respective timestamps $\{l_k\}$ in a series of events at $\{t_n\}$, such that $\{l_k\} \subseteq \{t_n\}$, a data publisher might release this information by: - -\begin{enumerate} - \item Selecting a set of options (Section~\ref{subsec:lmdk-set-opts}) consisting of different possible versions of $\{l_k\}$. - - \mk{`option' or `candidate'?} - - This could be: - - \begin{itemize} - \item either a random set of $k$ other timestamps similar to the actual {\thething} timestamps (Section~\ref{subsec:lmdk-rnd}), - \item or a set including $\{l_k\}$ and $x \in [1, n - k]$ additional dummy timestamps (Section~\ref{subsec:lmdk-dum-gen}). - \end{itemize} - - \item Releasing a privacy-preserving version of the {\thething} timestamps (Section~\ref{subsec:priv-opt-sel}). - We utilize the exponential mechanism with a utility function that calculates an indicator for each of the options in the set that we selected in the previous step. - The utility depends on the positioning of the {\thething} timestamps of an option in the series, e.g.,~the distance from the previous/next {\thething}, the distance from the start/end of the series, etc. -\end{enumerate} - -Following this process allows the release, and thereafter processing, of {\thething} timestamps. -Thus, we provide an extra layer of privacy protection when we separate {\thethings} from regular events. +One approach would be to utilize the randomized response (described in detail in Section~\ref{subsec:prv-mech}) and randomize the answer to the question \emph{`Is the current event a {\thething}?'} for every timestamp in $T \supseteq L$ of the time series $S_T$. +However, this could result in a new {\thething} set $L'$ that does not include all (or even any) of the timestamps in $L$. +This contradicts the main idea of {\thething} privacy, i.e.,~take into account all {\thethings} at every timestamp.