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Christian Grothoff 2016-07-03 12:13:18 +02:00
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doc/paper/taler.tex
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@ -132,7 +132,7 @@ instantly that a transaction is valid.
\begin{figure}[h] \begin{figure}[h]
\centering \centering
\begin{tikzpicture} \begin{tikzpicture}
\tikzstyle{def} = [node distance= 5em and 7em, inner sep=1em, outer sep=.3em]; \tikzstyle{def} = [node distance= 1em and 11em, inner sep=1em, outer sep=.3em];
\node (origin) at (0,0) {}; \node (origin) at (0,0) {};
\node (exchange) [def,above=of origin,draw]{Exchange}; \node (exchange) [def,above=of origin,draw]{Exchange};
\node (customer) [def, draw, below left=of origin] {Customer}; \node (customer) [def, draw, below left=of origin] {Customer};
@ -194,11 +194,8 @@ Yet, there are several major irredeemable problems inherent in their designs:
\item Bitcoin transactions have pseduononymous recipients, making taxation \item Bitcoin transactions have pseduononymous recipients, making taxation
hard to systematically enforce. hard to systematically enforce.
The Zerocoin extension makes this worse. The Zerocoin extension makes this worse.
% FIXME: need refs for following claim: \item Bitcoin introduces a new currency, creating additional
\item Bitcoin seemingly requires speculation to offset the mining cost, financial risks from currency fluctuation.
creating fluctuations in value, and making it hard to bind to national
currencies. These fluctuations may be desirable in a high-risk investment
instrument, but they make Bitcoin unsuitable as a medium of exchange.
\item Anyone can start an alternative Bitcoin transaction chain, \item Anyone can start an alternative Bitcoin transaction chain,
called an AltCoin, and, if successful, reap the benefits of the low called an AltCoin, and, if successful, reap the benefits of the low
cost to initially create coins cheaply as the proof-of-work cost to initially create coins cheaply as the proof-of-work
@ -211,15 +208,13 @@ Yet, there are several major irredeemable problems inherent in their designs:
% currency exchange and exacerbates the problems with currency fluctuations. % currency exchange and exacerbates the problems with currency fluctuations.
\end{itemize} \end{itemize}
GreenCoinX\footnote{\url{https://www.greencoinx.com/}} is a more %GreenCoinX\footnote{\url{https://www.greencoinx.com/}} is a more
recent AltCoin where the company promises to identify the owner of %recent AltCoin where the company promises to identify the owner of
each coin via e-mail addresses and phone numbers. While it is unclear %each coin via e-mail addresses and phone numbers. While it is unclear
from their technical description how this identification would be %from their technical description how this identification would be
enforced against a determined adversary, the resulting payment system %enforced against a determined adversary, the resulting payment system
would also merely impose a totalitarian financial panopticon on a %would also merely impose a financial panopticon on a BitCoin-style
BitCoin-style money supply and transaction model, thus largely %money supply and transaction model.
combining what we would consider to be the drawbacks of existing
credit card systems.
\subsection{Chaum-style electronic cash} \subsection{Chaum-style electronic cash}
@ -238,10 +233,10 @@ include:
recover funds from delinquent customers via the legal system. recover funds from delinquent customers via the legal system.
Any system that fails to be self-enforcing creates a major Any system that fails to be self-enforcing creates a major
business risk for the exchange and merchants. business risk for the exchange and merchants.
In 1983, there were merchants without network connectivity, making that % In 1983, there were merchants without network connectivity, making that
feature relevant, but today network connectivity is feasible for most % feature relevant, but today network connectivity is feasible for most
merchants, and saves both the exchange and merchants the business risks % merchants, and saves both the exchange and merchants the business risks
associated with deferred fraud detection. % associated with deferred fraud detection.
\item % In addition to the risk of legal disputes with fraudulent \item % In addition to the risk of legal disputes with fraudulent
% merchants and customers, % merchants and customers,
Chaum's published design does not clearly Chaum's published design does not clearly
@ -293,21 +288,21 @@ to what degree the implementation is even complete. Only a partial
description of the Opencoin protocol is available to date. description of the Opencoin protocol is available to date.
\subsection{Peppercoin} %\subsection{Peppercoin}
Peppercoin~\cite{rivest2004peppercoin} is a microdonation protocol. %Peppercoin~\cite{rivest2004peppercoin} is a microdonation protocol.
The main idea of the protocol is to reduce transaction costs by %The main idea of the protocol is to reduce transaction costs by
minimizing the number of transactions that are processed directly by %minimizing the number of transactions that are processed directly by
the exchange. Instead of always paying, the customer ``gambles'' with the %the exchange. Instead of always paying, the customer ``gambles'' with the
merchant for each microdonation. Only if the merchant wins, the %merchant for each microdonation. Only if the merchant wins, the
microdonation is upgraded to a macropayment to be deposited at the %microdonation is upgraded to a macropayment to be deposited at the
exchange. Peppercoin does not provide customer-anonymity. The proposed %exchange. Peppercoin does not provide customer-anonymity. The proposed
statistical method by which exchanges detect fraudulent cooperation between %statistical method by which exchanges detect fraudulent cooperation between
customers and merchants at the expense of the exchange not only creates %customers and merchants at the expense of the exchange not only creates
legal risks for the exchange, but would also require that the exchange learns %legal risks for the exchange, but would also require that the exchange learns
about microdonations where the merchant did not get upgraded to a %about microdonations where the merchant did not get upgraded to a
macropayment. It is therefore unclear how Peppercoin would actually %macropayment. It is therefore unclear how Peppercoin would actually
reduce the computational burden on the exchange. %reduce the computational burden on the exchange.
\section{Design} \section{Design}
@ -518,7 +513,7 @@ shared with others, they become co-owners of the coin. Knowledge of
the private key of the coin enables the owner to spent the coin. the private key of the coin enables the owner to spent the coin.
\subsection{Coin spending} % \subsection{Coin spending}
A customer spends a coin at a merchant by cryptographically signing a A customer spends a coin at a merchant by cryptographically signing a
{\em deposit authorization} with the coin's private key. A deposit {\em deposit authorization} with the coin's private key. A deposit
@ -1156,6 +1151,12 @@ the participants have to disclose their core secrets.
\bibliographystyle{alpha} \bibliographystyle{alpha}
\bibliography{taler,rfc} \bibliography{taler,rfc}
\vfill
\begin{center}
\Large Demonstration available at \url{https://demo.taler.net/}
\end{center}
\vfill
\newpage \newpage
\appendix \appendix