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-rw-r--r-- | comparison/comparison.tex | 87 |
1 files changed, 69 insertions, 18 deletions
diff --git a/comparison/comparison.tex b/comparison/comparison.tex index 45a6f64..ab7f6d6 100644 --- a/comparison/comparison.tex +++ b/comparison/comparison.tex @@ -32,7 +32,7 @@ \newcommand\Y{\ding{51}} % {\checkmark} \newcommand\N{\ding{55}} -\begin{tabular}{r|ccccccccccccc} +\begin{tabular}{r|cccccccccccccc} & \rot{Instant enforcement} & \rot{Robust anonymity} & @@ -42,8 +42,10 @@ \rot{Transferability} & \rot{Taxability} & % -\rot{Withdrawal cost} & -\rot{Deposit cost} & +% \rot{Withdrawal cost} & \rot{Deposit cost} & +\rot{Trustless anonymity} & +\rot{Realistic Exchange Storage} & +\rot{Cryptographic Batching} & \rot{Change} & % \rot{Robust anonymity} & @@ -54,27 +56,66 @@ Taler & \Y & \Y & \Y & \N & S & \Y -& $\log n$ & $\log n$ & ON +% & $\log n$ & $\log n$ +& \Y & \Y & \N & ON & \Y & \Y & \Y & Anon \\ % TODO: Just omit this straw-man online Chaum in favor on HINDE Chaum Online & \Y & ? & \Y? & \N & S & \N -& $\log n$ & $\log n$ & ON +% & $\log n$ & $\log n$ +& \Y & \Y & \N & ?? & \Y? & \N & \N & ? \\ HINDE & \Y? & \Y & \Y? & \N & S & \N -& $\log n$ & $\log n$ & ON +% & $\log n$ & $\log n$ +& \Y & \Y? & \N & ?? & \Y? & \N? & \N? & ? \\ Chaum Offline & \N & ? & \Y? & \N & S & \N? -& $\log n$ & $\log n$ & ON +% & $\log n$ & $\log n$ +& \Y & \N? & \N? & OFF & \Y? & \N? & \N? & ? +\\ +Compact ECash \cite{?compact?} +& \N & ? & \Y? +& \N & S & \N? +% & $\log n$ & $\log n$ +& \Y? & \N & W & OFF +& \N & \N? & \N? & \N? +\\ +Martens \cite{Martens2015} +& \N & ? & \Y? +& \N & S & \N? +% & $\log n$ & $\log n$ +& \Y? & \N & W & OFF +& \N & \N? & \N? & \N? +\\ +Divisible ECash \cite{CPST-DivisibleMadePractical,CPST-CutDownTheTree} +& \N & ? & \Y? +& \N & S & \N? +% & $\log n$ & $\log n$ +& \N & \N & W & OFF +& \N & \N? & \N? & \N? +\\ +Compact Taler +& \Y & \Y & \Y +& \N & S & \Y +% & $\log n$ & $\log n$ +& \Y & \Y & W & ON +& \Y & \Y & \Y & Anon +\\ +Divisible Taler +& \Y & \Y & \Y +& \N & S & \Y +% & $\log n$ & $\log n$ +& \N & \Y & WD & ON +& \Y & \Y & \Y & Anon \\ \hline \end{tabular} @@ -132,18 +173,28 @@ Chaum Offline \item \textbf{Endorsed.} Separation of the coin and permission to spend it, see \cite{camenisch2007endorsed}. Allows fair exchange (?). \item \textbf{Refunds.} Anonymous/Deanonymizing/Payment/None/Unspecified - \item \textbf{Anonymity Without Trusted Setup / ``Trustless anonymity``.} A trusted stup is be problematic; - while the exchange is fixed, the customers/merchant are not, so - distributed key generation isn't always an option. It makes it hard to instantiate the scheme - and hard to trust the deployed scheme. + + \item \textbf{Trustless anonymity} + At present, divisible ecash schemes entrust anonymity properties + to a trusted setup phase. Users cannot easily participate in this + trusted setup, so they must entrust some party with their anonymity, + and instantiating such schemes becomes difficult. + By comparison, blind sugnatures normally provide information theoretic security. \item \textbf{Realistic Exchange Storage Requirements.} - In schemes that have divisibility, the exchange still needs to - store the smallest denomination. Unless the scheme also has multiple denominations, - this storage requirements are unrealistic. - \item \textbf{Cryptographic Batching.} Some schemes allow - withdrawing a wallet with $2^\ell$ coins in $O(1)$ with - $O(1)$ storage and $O(1)$ batch spending. - \item \textbf{Information theoretical blinding/anonymity}. + Both compact and divisible ecash schemes require the exchange store + coins only as the smallest denomination to prevent double spending. + In practice, these schemes should be adjusted to store larger + denominations or else the exchange's storage requirments would + become unrealistic, but doing so + \item \textbf{Cryptographic Batching.} + Compact ECash schemes provide withdrawal operations that extract + many coins with one single withdrawal, reducing overall bandwidth + for fixed denomination values, but not computation. %% VERIFY + Divisible ECash schemes batch both withdrawal and deposit operations, + providing greater bandwith reduction, and possibly computaiton + reduction. These savings are limited however by the exchange's + storage requirments, and divisible schemes depend upon trusted setup + for their anonymity properties. \end{itemize} |