donau

commit 3368b0cd5db37549a4637d5a9f342f8119f11edb
parent 0addb20f4af5d12633df53fa9719100328f1ef9a
Author: Casaburi Johannes <johannes.casaburi@students.bfh.ch>
Date:   Tue, 17 Oct 2023 13:21:11 +0200

[doc] some adjustments

Diffstat:
M
doc/flows/main.tex
 | 
37
+++++++++++++++++++------------------

1 file changed, 19 insertions(+), 18 deletions(-)
diff --git a/doc/flows/main.tex b/doc/flows/main.tex
@@ -21,21 +21,23 @@
 
 \section{Definitions}
 \begin{itemize}
-  \item \textbf{Cryptographic Hash Function} $H$
+  \item \textbf{Cryptographic Hash Function} $H(m)$ where $m$ is a message.
 
-  \item \textbf{Signing Function} $Sign$
+  \item \textbf{Signing Function} $Sign(m,k)$ where $m$ is a message and $k$ is the key used to sign the message.
 
-  \item \textbf{Signature} $S$
+  \item \textbf{Blinding Function} $Blind(m,b)$ where $m$ is a message and $b$ is the blinding factor used to blind the message.
+
+  \item \textbf{Unblinding Function} $Unlind(s,b)$ where $s$ is a blind signature and $b$ is the blinding factor.
 
-  \item \textbf{Blind Signature} $BS$
+  \item \textbf{Signature} $S$
 
-  \item \textbf{Blinding Factor} $b$
+  \item \textbf{Blind Signature} $S^b$
 
   \item \textbf{Donation Unit} $DU = (K_{pub}, K_{priv})$: Smallest structure representing a donation confirmation unit. Consists of a Public key $K_{pub}$ and Private key $K_{priv}$. Equivalent in Taler is "denomination".
 
   \item \textbf{Unique Donor Identifier} $UDI = \langle H(TAXID, SALT), NONCE \rangle$
 
-  \item \textbf{Blinded Unique Donor Identifier} $BUDI = \langle B_{UDI}, H(K_{pub}) \rangle$, blinded to protect the privacy of the donor
+  \item \textbf{Blinded Unique Donor Identifier} $BUDI = \langle S^b_{UDI}, H(K_{pub}) \rangle$, blinded to protect the privacy of the donor
 
   \item \textbf{Donation Receipt} $DR = \langle UDI, S_{UDI}, H(K_{pub}) \rangle$
 
@@ -67,8 +69,7 @@
   \item The donor blinds the $UDI$'s using a \textbf{different} blinding factor $b$ for every $UDI$.
 
   \begin{align}
-      B_{UDI} &= blind(b,UDI, K_{pub}) \\
-      BUDI &= \langle B_{UDI}, H(K_{priv}) \rangle
+      BUDI &= \langle Blind(\langle UDI, K_{pub} \rangle, b), H(K_{pub}) \rangle
   \end{align}
 
 \item The donor sends the $BUDI$'s as well as the corresponding payment to the charity.
@@ -81,27 +82,27 @@
   \item The charity signs (using EdDSA) a structure containing all unsigned $BUDI$'s coming from the donor.
 
   \begin{align}
-      S_C = Sign(\langle BUDI_1, BDUI_2, .. \rangle, C_{priv})
+      S_{C} = Sign(\langle BUDI_1, BDUI_2, .. \rangle, C_{priv})
   \end{align}
 
-  \item The charity sends this structure and the signature $S_C$ to the Donau.
+  \item The charity sends this structure $\langle BUDI_1, BDUI_2, .. \rangle$ and the signature $S_{C}$ to the Donau.
 \end{enumerate}
 
 \subsubsection{Donau sends back the blind signed $UDI$'s to charity}
 \begin{enumerate}
   \item The Donau:
     \begin{enumerate}
-      \item verifies the signature $S_C$ on the structure.
+        \item verifies the signature $S_{C}$ on the structure.
 
       \item increments the current amount of donations received per year of the charity. This value is increased by the total amount of the $BUDI$'s, if the increment does not exceed the annual limit.
 
-      \item blind signs all the $BUDI$'s using the $DU$ private keys $K_{priv}$ matching the public keys used in $H(K_{pub})$.
+      \item signs all the $BUDI$'s using the $DU$ private keys $K_{priv}$ matching the public keys $H(K_{pub})$ used in the $BUDI$.
 
         \begin{align}
-            BS_D = Sign(BUDI, K_{priv})
+            S^b_{K} = Sign(BUDI, K_{priv})
         \end{align}
 
-    \item sends back the blind signatures ($S_D$'s) to the charity.
+    \item sends back the blind signatures ($S^b_{K}$'s) to the charity.
     \end{enumerate}
 
   \item The charity transmits the blind signatures to the donor.
@@ -109,7 +110,7 @@
   \item The donor unblinds the $BUDI$'s to get the signed $UDI$'s. This results in the \textbf{Donation Receipt} $DR$ consisting of the $UDI$, the signature $S_{UDI}$ and the Hash of the $DU$ public key $H(K_{pub})$.
 
   \begin{align}
-      S_{UDI} &= unblind(BS_D, b) \\
+      S_{UDI} &= Unblind(S^b_{K}, b) \\
       DR &= \langle UDI, S_{UDI}, H(K_{pub}) \rangle
   \end{align}
 \end{enumerate}
@@ -129,10 +130,10 @@
   \end{itemize}
 
   \item The Donau signs over the total amount,
-      year and $H(TAXID, SALT)$ and sends the signature and the total amount so far back to the donor. This results in the \textbf{Donation Statement} $DS$.
+      year and $H(TAXID, SALT)$ and sends the signature and the total amount so far back to the donor. This results in a final signature called the \textbf{Donation Statement} $DS$.
 
     \begin{align}
-        DS = Sign(\langle AMOUNT_{Total}, YEAR, H(TAXID, SALT) \rangle)
+        DS = Sign(\langle AMOUNT_{Total}, YEAR, H(TAXID, SALT) \rangle, D_{priv})
     \end{align}
 \end{enumerate}
 
@@ -140,7 +141,7 @@
 \begin{enumerate}
   \item The donor generates a QR code:
     \begin{align}
-      QR = \langle TAXID, SALT, DS, YEAR, AMOUNT \rangle
+      QR = \langle TAXID, SALT, DS, YEAR, AMOUNT \rangle %version?
     \end{align}
 
   \item The validator scans the QR code and verifies the signature in the $DS$.