diff options
Diffstat (limited to 'comparison')
-rw-r--r-- | comparison/comparison.tex | 102 |
1 files changed, 51 insertions, 51 deletions
diff --git a/comparison/comparison.tex b/comparison/comparison.tex index 88db20d..556354d 100644 --- a/comparison/comparison.tex +++ b/comparison/comparison.tex @@ -21,6 +21,8 @@ } \newcommand*\rot{\multicolumn{1}{R{45}{1em}}}% no optional argument here, please! +\newcolumntype{H}{>{\setbox0=\hbox\bgroup}c<{\egroup}@{}} + \title{E-Cash Comparison} \date{\today} @@ -32,88 +34,86 @@ \newcommand\Y{\ding{51}} % {\checkmark} \newcommand\N{\ding{55}} -\begin{tabular}{r|ccccccccccccc} +\begin{tabular}{r|cccHHcccccc} & \rot{Instant enforcement} & \rot{Robust anonymity} & \rot{Key expiration} & % -\rot{Traceability} & -\rot{Transferability} & +&% \rot{Traceability} & +&% \rot{Transferability} & \rot{Taxability} & % % \rot{Withdrawal cost} & \rot{Deposit cost} & \rot{Trustless anonymity} & -\rot{Realistic Exchange Storage} & -\rot{Cryptographic Batching} & -\rot{Change} & +\rot{Realistic exchange storage} & +\rot{Cryptographic batching} & % -\rot{Receipts} & -\rot{Endorsed} & -\rot{Refunds} +\rot{Change} & +\rot{Receipts \& Refunds} \\ \hline Taler & \Y & \Y & \Y & \N & S & \Y % & $\log n$ & $\log n$ -& \Y & \Y & \N & ON -& \Y & \Y & Anon +& \Y & \Y & \N +& ON & \Y \\ Digicash \cite{chaum1983,schoenmakers1997security} & \Y & \Y & \Y & \N & S & \N % & $\log n$ & $\log n$ -& \Y & \Y & \N & \N -& \N & \N & ? +& \Y & \Y & \N +& \N & \N \\ Tracz \cite{tracz2001} % HINDE & \Y & \Y & %? & \N & S & \N % & $\log n$ & $\log n$ -& \Y & \Y & \N & ON -& \N? & \N? & ? +& \Y & \Y & \N +& ON & \N \\ Offline Chaum \cite{chaum1990} & \N & \N & %? & \N & S & \N % & $\log n$ & $\log n$ -& \Y & \N & OFF -& \N? & \N? & ? +& \Y & \N & \N +& OFF & \N \\ Compact ECash \cite{camenisch2005} & \N & \N & %? & \N & S & \N % & $\log n$ & $\log n$ -& \Y & \N & W & OFF % We're guessing trustless anonymity because not trusted setup -& \N? & \N? & \N? +& \Y & \N & W % We're guessing trustless anonymity because not trusted setup +& OFF & \N \\ Martens \cite{maertens2015} & \N & \N & %? & \N & S & \N % & $\log n$ & $\log n$ -& \Y & \N & W & OFF % We're guessing trustless anonymity because not trusted setup -& \N? & \N? & \N? +& \Y & \N & W % We're guessing trustless anonymity because not trusted setup +& OFF & \N \\ Divisible ECash \cite{canard2015scalable} & \N & \N & %? & \N & S & \N % & $\log n$ & $\log n$ -& \N & \N & W & OFF -& \N? & \N? & \N? +& \N & \N & W +& OFF & \N \\ Compact Taler & \Y & \Y & \Y & \N & S & \Y % & $\log n$ & $\log n$ -& \Y & \Y & W & ON -& \Y & \Y & Anon +& \Y & \Y & W +& ON & \Y \\ Divisible Taler & \Y & \Y & \Y & \N & S & \Y % & $\log n$ & $\log n$ -& \N & \Y & WD & ON -& \Y & \Y & Anon +& \N & \Y & WD +& ON & \Y \\ \hline \end{tabular} @@ -149,46 +149,35 @@ Divisible Taler transaction. % TODO: Expand definition and cite the successor papers to Zerocash/BOLT % that handle regulation? - \item \textbf{Withdrawal cost.} - Asymptotic time and storage costs for the wallet during and after withdrawal. - Also frequently bandwidth costs for the withdrawal operation. %TODO: Details? - FIXME: Do we have a rigorous definition for this? Literature - only uses big-O for batched withdrawal/deposit. - \item \textbf{Deposit costs.} - Asymptotic time and storage costs for the exchange's double spending - protections required during deposit. - Frequently ignored, especially in ``constant time'' schemes. - FIXME: Do we have a rigorous definition for this? Literature - only uses big-O for batched withdrawal/deposit. \item \textbf{Change/Divisibility.} Which mechanism is used for divisibility? (None/OFFline/ONline). - \item \textbf{Receipts for spending.} + \item \textbf{Receipts \& Refunds.} The customer either can prove that they payed for - a contract, or they can get their (unlinkable) money back. - \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{Trustless anonymity} + a contract, or they can get their (unlinkable) money back, + which provides a form of fair exchange ala \cite{camenisch2007endorsed}. + Also merchants can issue refunds for completed transactions. + These operations must not introduce linkability or otherwise + compromise the customer's anonymity. + \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.} + By comparison, blind signatures normally provide information theoretic security. + \item \textbf{Realistic exchange storage requirements.} 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 + denominations or else the exchange's storage requirements would become unrealistic, but doing so - \item \textbf{Cryptographic Batching.} + \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 + providing greater bandwith reduction, and possibly computation reduction. These savings are limited however by the exchange's - storage requirments, and divisible schemes depend upon trusted setup + storage requirements, and divisible schemes depend upon trusted setup for their anonymity properties. \end{itemize} @@ -196,6 +185,17 @@ Divisible Taler These are discussion items that do not necessarily need to appear in the table. \begin{itemize} + \item \textbf{Withdrawal cost.} + Asymptotic time and storage costs for the wallet during and after withdrawal. + Also frequently bandwidth costs for the withdrawal operation. %TODO: Details? + FIXME: Do we have a rigorous definition for this? Literature + only uses big-O for batched withdrawal/deposit. + \item \textbf{Deposit costs.} + Asymptotic time and storage costs for the exchange's double spending + protections required during deposit. + Frequently ignored, especially in ``constant time'' schemes. + FIXME: Do we have a rigorous definition for this? Literature + only uses big-O for batched withdrawal/deposit. \item \textbf{Robustness under network failures.} Protocol aborts, including network failures, cannot compromise any party's financial security or the customer's anonymity. |