commit 32b0e9314fd72490f21fae6cc0b2366314476fd4
parent d5c58f2419e35f85334ead5d08cbc7bb2c4c9a1c
Author: Matyja Lukas Adam <lukas.matyja@students.bfh.ch>
Date: Tue, 3 Oct 2023 00:11:32 +0200
[doc] change terms
Diffstat:
| M | doc/flows/main.tex | | | 74 | ++++++++++++++++++++++++++++++++++++++------------------------------------ |
1 file changed, 38 insertions(+), 36 deletions(-)
diff --git a/doc/flows/main.tex b/doc/flows/main.tex
@@ -21,20 +21,21 @@
\section{Definitions}
\begin{itemize}
- \item $m :=$ \textbf{receipt} = smallest structure representing a donation confirmation unit, e.g. receipt for CHF1, CHF2. Equivalent in Taler is "coin".
- \item BDR := blinded donation receipt (collection of blinded receipts)
- \item $b :=$ Blinding factor
- \item $H :=$ Cryptographic hash function
- \item $statement_{year} :=$ sum of donations (receipts) for one specific year and specific donor
- \item $m' :=$ Blinded receipt
- \item $s :=$ Signed receipt
- \item $s' :=$ Blind signed receipt
- \item $mi, si, mi'...$ := number receipts/signatures if there are more than one eg. m1,m2...
- \item $m_{kj}$ or $mi_{kj} \Rightarrow kj$ := specific DONAU public key used to attribute a specific value to a receipt, e.g. k1 gives the receipt a value of 1, k2 a value of 2...
+ \item $DU :=$ \textbf{donation unit} = Smallest structure representing a donation confirmation unit, e.g. receipt for CHF1, CHF2. Equivalent in Taler is "coin".
+ \item $BDU :=$ blinded DU
+ \item $DR :=$ \textbf{donation receipt} = collection of DUs for one donation
+ \item $BDR :=$ collection of BDUs
+ \item $DS_{year} :=$ \textbf{donation statement} = sum of DRs for one specific year and specific donor
+ \item $b :=$ blinding factor
+ \item $H :=$ cryptographic hash function
+ \item $S_{sk} :=$ DU signature made with a donation unit secret key (from DONAU)
+ \item $BS_{pk} :=$ BDU signature with a donation unit secret key or public key
+ \item $DUi, Si, DRi...$ := number entities if there are more than one eg. DU1,DU2...
+ \item $BS_{pk/kj}$ or $BS_{sk/kj}$ or $S_{sk/kj} \Rightarrow kj$ := specific DONAU public key used to attribute a specific value to a DU, e.g. k1 gives the DU a value of 1, k2 a value of 2...
\end{itemize}
-\subsection{Receipt}
-The NONCE is used to uniquely distinguish receipts of the same value ("create a fresh receipt"). Otherwise the DONAU would refuse receipts containing donations of equal amount to the same charity, since this would be seen as "double spending". To simplify the thought process, the NONCE can be thought of as a "receipt ID".
+\subsection{Donation Unit (DU)}
+The NONCE is used to uniquely distinguish DU of the same value ("create a fresh DU"). Otherwise the DONAU would refuse DUs containing donations of equal amount to the same charity, since this would be seen as "double spending". To simplify the thought process, the NONCE can be thought of as a "DU ID".
\begin{align}
m := \langle H(TAXID, SALT), NONCE \rangle
@@ -53,68 +54,68 @@ The NONCE is used to uniquely distinguish receipts of the same value ("create a
\subsection{Step 1: Donor donates to charity}
\begin{enumerate}
- \item The donor downloads the donation unit/receipt public keys for the corresponding year from the DONAU.
+ \item The donor downloads the DU public keys for the corresponding year from the DONAU.
- \item To donate 5 Euros the donor has to generate 2 receipts (a 1 Euro and 4 Euro receipt). The donor generates receipts $m1$ and $m2$ which include a salted hash of the tax number (here TAXID) and a NONCE.
+ \item To donate 5 Euros the donor has to generate 2 DUs (a 1 Euro and 4 Euro DU). The donor generates DUs $DU1$ and $DU2$ which include a salted hash of the tax number (here TAXID) and a NONCE.
\begin{align}
- m1 = \langle H(TAXID, SALT), NONCE_1 \rangle \\
- m2 = \langle H(TAXID, SALT), NONCE_2 \rangle
+ DU1 = \langle H(TAXID, SALT), NONCE_1 \rangle \\
+ DU2 = \langle H(TAXID, SALT), NONCE_2 \rangle
\end{align}
- \item The donor blinds the receipts using two different blinding factors $b_1, b_2$.
+ \item The donor blinds the DUs using two different blinding factors $b_1, b_2$.
\begin{align}
- m1' = m1 \cdot b_1^{e_{1EUR}} \mod n_{1EUR} \\
- m2' = m2 \cdot b_2^{e_{4EUR}} \mod n_{4EUR}
+ BDU1 = BDU1 \cdot b_1^{e_{1EUR}} \mod n_{1EUR} \\
+ BDU2 = BDU2 \cdot b_2^{e_{4EUR}} \mod n_{4EUR}
\end{align}
- \item The Donor signs the receipts using the correct DONAU public keys. This gives the receipts their respective value.
+ \item The Donor signs the DUs using the correct DONAU public keys. This gives the DUs their respective value.
\begin{align}
- m1'_{k1} = sign_{k1}(m1') \\
- m2'_{k4} = sign_{k4}(m2')
+ BS1_{pk/k1} = sign_{pk/k1}(BDU1) \\
+ BS2_{pk/k4} = sign_{pk/k4}(BDU2)
\end{align}
- \item The donor sends the blinded receipts (BDR) $m1'$ and $m2'$ as well as the signatures $m1'$ and $m2'$ to the charity in addition to the payment of 3 Euros.
+ \item The donor sends the blinded DUs (BDR) $BDU1$ and $BDU2$ as well as the signatures $BS1_{pk/k1}$ and $BS2_{pk/k4}$ to the charity in addition to the payment of 5 Euros.
\end{enumerate}
-\subsection{Step 2: Charity sends signed receipt to DONAU}
+\subsection{Step 2: Charity sends signed DUs to DONAU}
\begin{enumerate}
\item The charity verifies that the amount requested for signing is lower or equal to the effective amount of the donation.
- \item The charity signs (using EdDSA) a structure containing all unsigned receipts coming from the donor.
+ \item The charity signs (using EdDSA) a structure containing all unsigned DUs coming from the donor.
\item The charity sends this structure and the signature to the DONAU.
\end{enumerate}
-\subsection{Step 3: DONAU sends back blind signed receipt to charity}
+\subsection{Step 3: DONAU sends back blind signed DUs to charity}
\begin{enumerate}
\item The DONAU:
\begin{enumerate}
\item verifies the charity Signature on the structure.
- \item verifies the signature of every receipt with it's private keys.
- \item increments the current year amount of the charity by the total amount of the receipts, if the increment does not exceed the annual limit.
- \item blind signs (using RSA/Schnorr) all the receipts
+ \item verifies the signature of every DU with it's private keys.
+ \item increments the current year amount of the charity by the total amount of the BDR, if the increment does not exceed the annual limit.
+ \item blind signs (using RSA/Schnorr) all the DUs
\begin{align}
s_1' = m_1'^{(d_{E1})} \emph{mod ?} \\
s_2' = m_2'^{(d_{E2})} \emph{mod ?}
\end{align}
- \item sends back the blind signed receipts to the charity
+ \item sends back the blind signed DUs to the charity
\end{enumerate}
- \item The charity transmits the blind signed receipts to the donor.
- \item The donor unblinds the receipts.
+ \item The charity transmits the blind signed DUs to the donor.
+ \item The donor unblinds the signatures.
\begin{align}
s_1 = s_1' \cdot b^{-1} \mod n_1 \\
s_2 = s_2' \cdot b^{-1} \mod n_2
\end{align}
\end{enumerate}
-\subsection{Step 4: Donor sends receipts to DONAU, DONAU sends back statement}
+\subsection{Step 4: Donor sends DR to DONAU, DONAU sends back donation statement (DS)}
\begin{enumerate}
- \item The donor sends the collection of all $(mi, si, kj)$ to the DONAU. The donation receipts are always sent to the DONAU right after the donor has unblinded the receipts. The corresponding year is sent with.
+ \item The donor sends the collection of all $(mi, si, kj)$ to the DONAU. The DR is always sent to the DONAU right after the donor has unblinded the DUs. The corresponding year is sent with.
\item For each $(mi, si, kj)$ The DONAU...
\begin{itemize}
\item verifies that $kj$ is one of the valid public keys corresponding to the year indicated.
\item verifies if $si$ is a correct signature with the corresponding secret key.
- \item verifies that the hash of the TAXID and the salt is the same as in other receipts (how to solve the problem with multiple wallets?)
+ \item verifies that the hash of the TAXID and the salt is the same as in other DUs (how to solve the problem with multiple wallets?)
\item verifies that the nonce is different from each ever used nonce of this donor for the corresponding year.
\item if all of this is the case, it adds the amount corresponding to the public key to the total donation amount for the year.
\end{itemize}
@@ -139,7 +140,8 @@ The NONCE is used to uniquely distinguish receipts of the same value ("create a
\item version of the protocol(one byte)
\end{itemize}
- \item The validator scans the QR code and validates that the signature corresponds to the current DONAU statement signing key.
+ \item The validator scans the QR code and validates that the signature corresponds to the current DONAU DS signing key.
\end{enumerate}
\end{document}
+
