donau-paper.tex (5140B)
1 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 2 % TODO : 3 % - Reduce the size to 13 pages for the main text (excluding 4 % bibliography) 5 % - Add some bibliographical references (for the motivation). 6 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 7 %\documentclass{taler} % full lenth boiler plate 8 %\documentclass{taler-short} % for short deliverables with less boiler plate 9 \documentclass[letterpaper,twocolumn,10pt]{article} 10 \usepackage{usenix-2020-09} 11 12 \newif\ifanonymous 13 \anonymoustrue 14 15 \usepackage{xcolor} 16 \usepackage{amsmath} 17 \usepackage{amsthm} 18 \theoremstyle{definition} 19 \newtheorem{definition}{Definition} 20 %\definecolor{linkcolor}{rgb}{0.65,0,0} 21 %\definecolor{citecolor}{rgb}{0,0.4,0} 22 %\definecolor{urlcolor}{rgb}{0,0,0.65} 23 %\usepackage[colorlinks=true, linkcolor=linkcolor, urlcolor=urlcolor, citecolor=citecolor]{hyperref} 24 25 \usepackage{tikz} 26 \usepackage{listings} 27 \usepackage{graphicx} 28 \date{} 29 \title{Design of a privacy friendly tax deduction system for donations} 30 31 % \author{Emmanuel Benoist, Johannes Casaba, Bob Goudriaan, 32 % Christian Grothoff, Tanja Lange, Michiel Leenaars, 33 % Jonathan Levin, Lukas Matyja} 34 35 \author{\ } 36 37 % \author{ 38 % {\rm Bob Goudriaan}\\ 39 % NLnet Foundation 40 % \and 41 % {\rm Christian Grothoff}\\ 42 % Bern University of Applied Sciences 43 % \and 44 % {\rm Tanja Lange}\\ 45 % Technical University of Eindhoven 46 % \and 47 % {\rm Michiel Leenaars}\\ 48 % NLnet Foundation 49 % \and 50 % {\rm Jonathan Levin}\\ 51 % XXXXX 52 % } % end author 53 54 \begin{document} 55 \maketitle 56 57 \begin{abstract} 58 Donations have complex requirements that also 59 vary by country. Building on privacy-friendly digital cash protocols 60 (which enable customers to pay anonymously using blind signatures) 61 we created the {\em Donau} system to handle key use-cases for 62 privacy-preserving donations. 63 This paper explains how our Free Software implementation addresses the 64 most common requirements, and also elaborates how others could be 65 instantiated with significant changes or additions to the design. 66 67 The Donau system achieves privacy for donors while providing 68 them with a proof that they donated to some registered charity. 69 The charity does not learn the identity of the donor and the tax 70 authority does not learn which charities received donations from 71 a particular donor. However, authorities do learn the total amount 72 donated to a charity by all donors. 73 74 Our design introduces a new entity, the {\em Donation Authority} 75 which operates the {\em Donau} service. The {\em Donau} would typically 76 be operated by or on behalf of the tax authority and ensures that 77 only recognized charities can register and provide proofs to their 78 donors. Also this entity does not learn who donated to which charity. 79 80 Society would benefit from the Donau system as it simplifies 81 filing taxes, contributes to fair taxation, and eliminates 82 privacy-concerns from charitable giving. 83 84 \ifodd0 85 %\begin{abstract} 86 GNU Taler is a privacy-friendly payment protocol that offers full anonymity to 87 the customer, making their purchases anonymous and unlinkable not only to 88 third parties but even to merchants and banks involved. While this payment 89 mechanism obviously can be used to make donations, the anonymity guarantees 90 seem at odds with the desire of donors to receive tax benefits for their 91 charitable donations. 92 93 The main contribution of this paper is the technical design and implementation 94 of a system that achieves privacy for the donor while providing them with a 95 proof that they donated to a charity. The charity does not learn the identity 96 of the donor and the tax authority does not learn which charities received the 97 donations. Our design introduces a new entity, the Donation Authority, which we 98 call Donau. This entity may be operated by the tax authority, and even then 99 they do not learn the identities of the charities and only get a summary 100 statement of all donations made by the tax payer in a certain timeframe. 101 102 The paper is based on our analysis of functional requirements for 103 privacy-preserving donations and of further desirable properties which 104 amount to requirements for some countries. We show how to realize some 105 of them within our design while showing how others could be 106 instantiated with significant changes or additions to the design. 107 \fi 108 \end{abstract} 109 110 %\reportkeywords{GNU Taler, Tax-deductible Donations. Donau, Donation Authority, 111 %Privacy-Preserving Payments} 112 113 114 115 \input{intro} 116 \input{requirements} % Michiel's part can go in this file 117 \input{technicaldesign} 118 \input{implementation2} 119 \input{discussion} 120 %\input{conclusion} 121 122 123 \ifodd0 124 125 \section*{Acknowledgments} 126 127 This work was funded by ANONYMIZED. 128 %in part by the European Commision through the 129 %Horizon Europe program under project number 101135475 (TALER). It also 130 %has received funding from the Swiss State Secretariat for Education, 131 %Research and Innovation (SERI). 132 % 133 We thank the tax authority of ANONYMIZED for an extensive and 134 constructive discussion on the subject. 135 136 \fi 137 138 \clearpage 139 \input{ethic} 140 \clearpage 141 142 143 144 145 \bibliographystyle{plainurl} 146 \bibliography{donau-paper,bibliography,tanja} 147 148 % Maybe for camera-ready? 149 \appendix 150 \input{appendix} 151 152 \input{app-impl} 153 %\input{implementation} 154 155 \end{document}