[taler-donau] branch master updated: multiple upload of donation receipts during a year, remove text fields from image, other adjustments

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lukas-matyja pushed a commit to branch master
in repository donau.

The following commit(s) were added to refs/heads/master by this push:
     new b829609  multiple upload of donation receipts during a year, remove 
text fields from image, other adjustments
b829609 is described below

commit b829609bca943864c665839b627a51c2aeee994f
Author: Matyja Lukas Adam <lukas.matyja@students.bfh.ch>
AuthorDate: Sat Sep 30 19:35:50 2023 +0200

    multiple upload of donation receipts during a year, remove text fields from 
image, other adjustments
---
 doc/flows/images/overview.png | Bin 61618 -> 326029 bytes
 doc/flows/main.tex            |  25 ++++++++++++++-----------
 2 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/doc/flows/images/overview.png b/doc/flows/images/overview.png
index 5e1d966..b3ae7f6 100644
Binary files a/doc/flows/images/overview.png and 
b/doc/flows/images/overview.png differ
diff --git a/doc/flows/main.tex b/doc/flows/main.tex
index c28046c..bf8aae3 100644
--- a/doc/flows/main.tex
+++ b/doc/flows/main.tex
@@ -22,6 +22,7 @@
 \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
@@ -47,7 +48,7 @@ The NONCE is used to uniquely distinguish receipts of the 
same value ("create a
 \subsection{Step 0: Initial setup}
 \begin{enumerate}
   \item The charity generates their own key pair.
-  \item The DONAU administrator registers the public key of the charity and 
sets the yearly donation limit.
+  \item The DONAU administrator registers the public key of the charity and 
sets the yearly donation limit for the charities.
 \end{enumerate}
 
 \subsection{Step 1: Donor donates to charity}
@@ -61,8 +62,7 @@ The NONCE is used to uniquely distinguish receipts of the 
same value ("create a
     m2 = \langle H(TAXID, SALT), NONCE_2 \rangle
   \end{align}
 
-  \item The donor blinds the receipts using two different blinding factors 
$b_1, b_2$ and sends them as $m1'$ and $m2'$ to the charity in addition to the 
payment of 3 Euros.
-
+  \item The donor blinds the receipts 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}
@@ -73,13 +73,15 @@ The NONCE is used to uniquely distinguish receipts of the 
same value ("create a
     m1'_{k1} = sign_{k1}(m1') \\
     m2'_{k4} = sign_{k4}(m2')
   \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.
 \end{enumerate}
 
 \subsection{Step 2: Charity sends signed receipt 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(EdDSA, more efficient than RSA-based signatures) a 
structure containing all unsigned receipts coming from the donor.
-  \item The charity sends this structure to the DONAU.
+  \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}
@@ -88,7 +90,7 @@ The NONCE is used to uniquely distinguish receipts of the 
same value ("create a
     \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.
+      \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 (RSA/Schnorr) all the receipts
     \end{enumerate}
   \begin{align}
@@ -106,18 +108,18 @@ The NONCE is used to uniquely distinguish receipts of the 
same value ("create a
 
 \subsection{Step 4: Donor sends receipts to DONAU, DONAU sends back statement}
 \begin{enumerate}
-  \item The donor sends the collection of all $(mi, si, kj)$ of the year to 
the DONAU.
+  \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 For each $(mi, si, kj)$ The DONAU...
 
   \begin{itemize}
-    \item verifies that $kj$ is one of it's currently valid public keys
+    \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
-    \item verifies that the nonce is different from the ones in other receipts
+    \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 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}
 
-  \item The DONAU then signs over the amount, year and hashed TAXID+salt and 
sends signature back to the donor
+  \item The DONAU then signs over the amount, year and hashed TAXID+salt and 
sends signature and the total amount so far back to the donor.
 
   \begin{align}
     sign(total amount, year, hash(TAXID, salt))
@@ -134,9 +136,10 @@ The NONCE is used to uniquely distinguish receipts of the 
same value ("create a
     \item signature received from the DONAU
     \item year
     \item amount for the year
+    \item version of the protocol(one byte)
   \end{itemize}
 
-  \item The validator scans the QR code. The app 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 statement signing key.
 \end{enumerate}
 
 \end{document}

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