concept.tex (10609B)
1 The Donau environment includes three stakeholders. 2 Donors, charities and the tax authority (See figure \ref{fig:stakeholders}). 3 The Donau itself is operated by the tax authority while maintaining a list of 4 verified charities. Each charity maintains a backend solution that allows it 5 to communicate with the Donau and the donors. 6 7 \begin{figure}[ht] 8 \begin{center} 9 \begin{tikzpicture} 10 \node (image) at (0,0) {\includegraphics[width=0.1\textwidth]{stickman}}; 11 \node at (0,-1.8) {Donor}; 12 %arrow 13 \draw (1,0) -- (7,0); 14 %charity 15 \node (image) at (8.5,0) {\includegraphics[width=0.15\textwidth]{charity}}; 16 \node at (8.5,-1.1) {Charity}; 17 %arrow 18 \draw (7,-1) -- (5,-2.5); 19 %server 20 \node (image) at (4,-3) { 21 \includegraphics[width=0.12\textwidth]{tax-authority}}; 22 \node at (4,-4.1) {Tax Authority}; 23 %arrow 24 \draw (1,-1) -- (3,-2.5); 25 \end{tikzpicture} 26 \end{center} 27 \caption{Stakeholders present in the Donau system.} \label{fig:stakeholders} 28 \end{figure} 29 30 \section{Issuing Donation Receipts} \label{issuing_donation_receipts} 31 When donating to a charity the donor sends the payment together with a receipt 32 request to the charity. 33 In order to link the donation to the donor so that the donation receipt cannot 34 be used by someone else, the donor's unique tax identification number is part 35 of the receipt request. 36 This tax ID does not cause a problem for anonymity as the whole receipt 37 including the tax ID is blinded (See section \ref{blind_signatures}). 38 39 In figure \ref{fig:issue receipt request} the blinded receipt is illustrated as 40 an envelope. The charity must verify if the payment was successful and if the 41 amount written in the receipt request is lower or equal the amount donated. 42 43 Next, if the charity approves the receipt request, it signs the unmodified 44 request and forwards the request to the Donau. 45 The Donau accepts only issued requests from recognized charities. For a charity 46 to be recognized, it must first be registered in the relevant Donau. 47 When the Donau receives an issue receipt request from a charity, it checks the 48 validity of the charity signature before the Donau issues the actual donation 49 receipt by signing the request. 50 51 This is different from current systems where the charity usually issues the 52 receipt. By shifting this task to the Donau, the receipts can easily be 53 verified and unlink the donor from the charity. 54 Because the Donau does only know the amount and the charity it is signing for, 55 this first step of issuing receipts anonymizes the data and provides privacy 56 for the donor. If the payment process also provides anonymity (as is the case 57 with GNU Taler) the donations are fully anonymous. 58 59 \begin{figure}[ht] 60 \begin{center} 61 \begin{tikzpicture} 62 \node (image) at (0,0) {\includegraphics[width=0.1\textwidth]{stickman}}; 63 \draw [-latex] (1,0) -- (4,0); 64 \node (image) at (2,0.5) {\includegraphics[width=0.08\textwidth]{letter}}; 65 \node at (2,0.5) {\Large{5}}; 66 \node (image) at (3.2,0.4) {\includegraphics[width=0.05\textwidth]{coins}}; 67 \node (image) at (5.3,0) {\includegraphics[width=0.15\textwidth]{charity}}; 68 \draw [-latex] (6.5,0) -- (9.5,0); 69 \node (image) at (8,0.5) {\includegraphics[width=0.08\textwidth]{letter}}; 70 \node (image) at (8,0.5) {\includegraphics[width=0.05\textwidth]{blue_wax}}; 71 \node at (8,0.5) {\Large{5}}; 72 \node (image) at (11,0) { 73 \includegraphics[width=0.12\textwidth]{servers}}; 74 \node at (11,-1.2) {Donau}; 75 \end{tikzpicture} \vspace{0.4cm} 76 \end{center} 77 \caption{Donor donates to a charity, sending a issue receipt request to the Donau} \label{fig:issue receipt request} 78 \end{figure} 79 80 Upon receiving the signed issue request from the charity, the Donau must verify 81 the charity signature and check that the yearly donation limit of the charity 82 is not exceeded. 83 After successful verification the Donau blind signs the donation receipt which 84 is then sent via the charity back to the Donor (See figure \ref{fig:issue 85 receipt response}). 86 The donor now unblinds the signature from the Donau to make it valid for the 87 unblinded receipt (for more information on blind signatures see section \ref{blind_signatures}). 88 The unblinded receipt gets saved locally on the donors device for later. 89 This process repeats for every donation. At the end of the year the donor may 90 have accumulated any number of these donation receipts. 91 92 \begin{figure}[ht] 93 \begin{center} 94 \begin{tikzpicture} 95 \node (image) at (0,0) {\includegraphics[width=0.1\textwidth]{stickman}}; 96 \draw [-latex] (4,0) -- (1,0); 97 \node (image) at (2.5,-0.5) {\includegraphics[width=0.08\textwidth]{letter}}; 98 \node (image) at (2.5,-0.5) {\includegraphics[width=0.05\textwidth]{red_wax}}; 99 \node at (2.5,-0.5) {\large{5}}; 100 \node (image) at (5.3,0) {\includegraphics[width=0.15\textwidth]{charity}}; 101 \draw [-latex] (9.5,0) -- (6.5,0); 102 \node (image) at (8,-0.5) {\includegraphics[width=0.08\textwidth]{letter}}; 103 \node (image) at (8,-0.5) {\includegraphics[width=0.05\textwidth]{red_wax}}; 104 \node at (8,-0.5) {\large{5}}; 105 \node (image) at (11,0) { 106 \includegraphics[width=0.12\textwidth]{servers}}; 107 \node at (11,-1.2) {Donau}; 108 \end{tikzpicture} \vspace{0.4cm} 109 \end{center} 110 \caption{Donor receives the signed receipts from the Donau} \label{fig:issue receipt response} 111 \end{figure} 112 113 \section{Summarize the Receipts}\label{summarize_the_receipts} 114 When it is time for the tax declaration (usually at the beginning of the next 115 year) the donor has to request a final donation statement signature from the 116 Donau, summarizing all the donation receipts of a year (see figure 117 \ref{fig:summarize receipts}). 118 This step combines the amounts of the donation receipts in a single total 119 amount. 120 This further protects the privacy of the donor as the individual donations 121 could be enough information to link up the specific donations to their 122 corresponding charity and donor. 123 Merging donation receipts also reduces the time and effort for the manual 124 verification of the tax authority as the donor generates a single QR-Code 125 containing the donation statement. This statement contains the total amount 126 donated, year, tax ID and the signature over all of these values. 127 This signature is used to verify the donation statement by the tax authority. 128 The donation statement can be requested multiple times during the year for save 129 keeping. The latest donation statement will always contain all the receipts of 130 a year - the old receipts (from previous statements of the year) and the new 131 donation receipts. 132 133 \begin{figure}[ht] 134 \begin{center} 135 \begin{tikzpicture} 136 \node (image) at (0,0) {\includegraphics[width=0.1\textwidth]{stickman}}; 137 %receipt 138 \node[rectangle, text width=1.65cm, align=center,font=\tiny, draw=black!80, thick, inner sep=2pt, fill=white] at (3,0.9) {AHVN13: 7560001010000}; 139 \node (image) at (3,0.9) {\includegraphics[width=0.04\textwidth]{red_wax}}; 140 \node at (3,0.9) {\small{9}}; 141 %receipt 142 \node[rectangle, text width=1.65cm, align=center,font=\tiny, draw=black!80, thick, inner 143 sep=2pt, fill=white] at (4,0.8) {AHVN13: 7560001010000}; 144 \node (image) at (4,0.8) {\includegraphics[width=0.04\textwidth]{red_wax}}; 145 \node at (4,0.8) {\small{1}}; 146 %receipt 147 \node[rectangle, text width=1.65cm, align=center,font=\tiny, draw=black!80, thick, inner 148 sep=2pt, fill=white] at (5,0.7) {AHVN13: 7560001010000}; 149 \node (image) at (5,0.7) {\includegraphics[width=0.04\textwidth]{red_wax}}; 150 \node at (5,0.7) {\small{5}}; 151 %arrows 152 \draw [-latex] (1,0.2) -- (7,0.2); 153 \draw [-latex] (7,-0.2) -- (1,-0.2); 154 %server 155 \node (image) at (8.5,0) { 156 \includegraphics[width=0.12\textwidth]{servers}}; 157 \node at (8.5,-1.2) {Donau}; 158 %donation statement 159 \node (image) at (4,-1) {\includegraphics[width=0.1\textwidth]{gold_wax}}; 160 \node at (4,-1) {\large{15}}; 161 \end{tikzpicture}\vspace{0.4cm} 162 \end{center} 163 \caption{The Donau summarizes the donation receipts and sends the statement back} \label{fig:summarize receipts} 164 \end{figure} 165 166 \section{Validation}\label{validation} 167 Once the donor has received the donation statement signature, he can summarize 168 them in a QR code. The donor must submit the QR-Code with his tax documents, 169 in order to claim the tax reduction (see figure \ref{fig:validation}). 170 The final check is made by the tax authority, by checking the donation 171 statement signature. If the signature is valid, this is the proof that the 172 specified donor indeed has donated the claimed amount in the indicated year. 173 174 \begin{figure}[ht] 175 \begin{center} 176 \begin{tikzpicture} 177 \node (image) at (0,0) {\includegraphics[width=0.1\textwidth]{stickman}}; 178 \node at (0,-1.8) {Donor}; 179 %arrow 180 \draw [-latex] (1,-0.5) -- (7,-0.5); 181 %QR-Code 182 \draw (2.7,2.5) -- (3.4,0.9); 183 \draw (4.9,2.5) -- (4.2,0.9); 184 \node (image) at (3.8,2) {\includegraphics[width=0.05\textwidth]{gold_wax}}; 185 \node at (3.8,2) {\small{15}}; 186 \node at (3.8,2.5) {\tiny{7560001010000}}; 187 \node at (3.8,1.3) {\small{2024}}; 188 \node (image) at (3.8,0.2) {\includegraphics[width=0.1\textwidth]{qr-donau}}; 189 %server 190 \node (image) at (8.5,0) { 191 \includegraphics[width=0.12\textwidth]{tax-authority}}; 192 \node at (8.5,-1.8) {Tax Authority}; 193 \end{tikzpicture}\vspace{0.4cm} 194 \end{center} 195 \caption{The tax authority verifies the statement previously created by the Donau} \label{fig:validation} 196 \end{figure} 197 198 The tax authority will not have any information to which charity the donor 199 has donated money. The tax authority only knows the total donated amount and 200 that every donation was made to one of the recognized charities in the 201 specified year. 202 This way the donor could make an anonymous donation and still have enough proof 203 to deduct the amount from taxes. 204 The Donau will keep track of the total amount of the donation receipts issued 205 for each charity, to enforce donation limits according to local law and 206 to prevent donation fraud. 207 208 \section{Incorporating the Donau}\label{incorporating_the_donau} 209 Every donor is delegated to only one specific Donau of his location where he is 210 able to issue and submit donation receipts for deducting taxes. 211 If a charity wants to be accepted in multiple tax areas, it has to be 212 registered by all the corresponding donation authorities. 213 To do so, the charities has to apply to the tax authorities. 214 The region for which a Donau is responsible depends on the tax area of the tax 215 authority and their reglementation of what is charitable. 216 One Donau could be responsible for a geographical area like a canton, a country 217 or even a confederation of states. 218 219