diff options
author | Florian Dold <florian.dold@gmail.com> | 2017-11-10 03:05:04 +0100 |
---|---|---|
committer | Florian Dold <florian.dold@gmail.com> | 2017-11-10 03:05:04 +0100 |
commit | 3076f1f17b1ace9d14ab42bd127d669056e66496 (patch) | |
tree | 25c47ef31246395613c1fbc64e7ac22f9b8c9f54 /games | |
parent | 629d44aa0e8bb90954f6ec086d590239fff67006 (diff) | |
download | papers-3076f1f17b1ace9d14ab42bd127d669056e66496.tar.gz papers-3076f1f17b1ace9d14ab42bd127d669056e66496.tar.bz2 papers-3076f1f17b1ace9d14ab42bd127d669056e66496.zip |
fixes
Diffstat (limited to 'games')
-rw-r--r-- | games/games.tex | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/games/games.tex b/games/games.tex index 22dd209..b57722b 100644 --- a/games/games.tex +++ b/games/games.tex @@ -242,7 +242,7 @@ given in literature. \section{Proofs} \subsection{Anonymity} -\paragraph{``Proof sketch''.} Proof by looking at withdraw/deposit/refresh transcripts. Do game hopping, replace +\paragraph{``Proof sketch''.} Proof by looking at withdraw/deposit/refresh transcripts seen by the adversary. Do game hopping, replace everything that's not random by something random (with computationally indistinguishable distribution) until everything that the adversary could see in a game has the same probability, and he must win with probability $1/2$. @@ -255,7 +255,8 @@ could see in a game has the same probability, and he must win with probability $ \end{itemize} \subsection{Income Transparency} -To win the game, the adversary must produce coins that are not in the wallet of any non-corrupted user. +To win the game, the adversary must produce enough coins that are not in the wallet of any non-corrupted user, but withdraw little +coins via corrupted users. \begin{lemma} The signatures on $C_1, \dots, C_\ell$ must have been obtained by using either \ora{Withdraw}, \ora{RefreshReveal} or \ora{Link}. @@ -267,15 +268,18 @@ To win the game, the adversary must produce coins that are not in the wallet of \begin{lemma} To win the Income Transparency game, the adversary must call $\ora{RefreshReveal}$ at least $(\kappa V_r - V_w) > 0$ times - in a way that causes the linking step to fail. + in a way that causes the linking step to fail. (This implies unforgeability.) +\end{lemma} + +\begin{lemma} + The probability to use \ora{RefreshCommit} and \ora{RefreshReveal} in a way that causes \algo{Link} to return $\bot$ at most $1/\kappa$. \end{lemma} \begin{theorem} - The adversary wins the Income Transparency game with with probability ... + The adversary wins the Income Transparency game with with probability at most $1 / \kappa$. \end{theorem} -Conclusion: Even the best adversary needs to waste $\kappa$ coins to obtain one untaxable coin. - +FIXME: We should also include what the expected ``untaxed'' money for the adversary is for each won game, vs. the money wasted. \section{Standard Definitions} \begin{definition}[One-more forgery] |