[taler-anastasis] branch master updated: worked on related work - thesis

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dennis-neufeld pushed a commit to branch master
in repository anastasis.

The following commit(s) were added to refs/heads/master by this push:
     new f9bd724  worked on related work - thesis
f9bd724 is described below

commit f9bd724a92eb0f29034a4e7e4ac85c3bc4e2015e
Author: Dennis Neufeld <address@hidden>
AuthorDate: Wed Feb 26 16:25:01 2020 +0000

    worked on related work - thesis
---
 doc/thesis/Journal.tex        |  2 +-
 doc/thesis/business_model.tex |  1 -
 doc/thesis/related_work.tex   | 26 ++++++++++++++++++++++++++
 doc/thesis/thesis.tex         |  5 ++++-
 4 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/doc/thesis/Journal.tex b/doc/thesis/Journal.tex
index b48645d..91a7a95 100644
--- a/doc/thesis/Journal.tex
+++ b/doc/thesis/Journal.tex
@@ -20,7 +20,7 @@
 \begin{document}
 \maketitle
 \section{Meeting 20.02.2020}
-Present at the Meeting where:"Dominik Meister, Dennis Neufeld and Christian 
Grothoff".
+Present at the Meeting were:"Dominik Meister, Dennis Neufeld and Christian 
Grothoff".
 \subsection{Reflection}
 It was the first meeting of the Bachelor's thesis. The main focus lied on the 
planing of the project and discussing the next steps. 
 The conclusion was there is alot of work to do and we need to focus from the 
beginning.
diff --git a/doc/thesis/business_model.tex b/doc/thesis/business_model.tex
index b32bc81..635fea2 100644
--- a/doc/thesis/business_model.tex
+++ b/doc/thesis/business_model.tex
@@ -1,7 +1,6 @@
 \section{Business model}
 
 \subsection{Executive Summary}
-\label{sec:bm_exsum}
 Project Anastasis was inspired by a discussion the GNU Taler team had with the 
European Central Bank, which informed them about a requirement for electronic 
wallets denominated in Euros to support password-less recovery. GNU Taler is a 
privacy-preserving microtransaction and electronic payment system based on free 
software. In consultation with Taler Systems SA we, Dominik Meister and Dennis 
Neufeld, decided to develop such a password-less recovery system within our 
bachelor thesis. We n [...]
 Having an agreement with Taler Systems SA our first customers will be the 
users of GNU Taler and Taler Systems SA themselves. Later on we also want to 
integrate Anastasis within other services like for example pEp which is also 
interested in our service. There are many other use cases Anastasis can be used 
for: Password Manager (like KeePass), electronic wallets for cryptocurrencies 
etc.
 There are some solutions out there for password recovery. But none of them is 
respecting privacy and enabling the users to remain in control of their data.
diff --git a/doc/thesis/related_work.tex b/doc/thesis/related_work.tex
new file mode 100644
index 0000000..5f11169
--- /dev/null
+++ b/doc/thesis/related_work.tex
@@ -0,0 +1,26 @@
+\section{Related work}
+
+\subsection{Secret sharing}
+As Anastasis uses some kind of secret sharing/secret splitting we want to give 
an overview of some of those algorithms.
+However, the scenario for Anastasis is slightly different from the usual 
secret sharing scenario. When it comes to secret sharing, there are usually 
several people who collectively want to restore a secret. For example, n people 
could work on a top secret project that is protected by a password. This 
password is now divided into several parts, which are distributed to the n 
people. Only when a certain number of the n persons combine their key parts in 
a certain way, the original password [...]
+With Anastasis, in contrast to the scenario just described, we have the case 
that only one person, namely the person who owns the password, may be able to 
recover the secret.
+
+\subsubsection{Trivial secret sharing}
+In the following we sign with t (threshold) the number of persons necessary to 
reconstruct a secret and with n the total number of persons a key share is 
given to.\\
+\\
+For the case t=1, it quickly becomes clear that only the unchanged secret is 
passed on to a number n of persons. It is obvious that such a case is 
undesirable and totally insecure in most cases.\\
+\\
+Then there is the trivial case with t=n, which in principle is also used in 
Anastasis. Here all n key/secret shares are needed to reconstruct the secret. 
In Anastasis we basically use the following procedure to split or reassemble a 
secret:
+
+\begin{itemize}
+       \item The secret must be encoded as an binary number s.
+       \item Generate n random numbers p\textsubscript{i} and give one of them 
to each player.
+       \item Store the result r of (s XOR p\textsubscript{1} XOR 
p\textsubscript{2} XOR ... XOR p\textsubscript{n})
+                       \\(XOR is bitwise exclusive or). For this r could be 
given to all players or just to a player n+1.
+       \item To recover the secret s, the n players have to add their numbers 
p\textsubscript{i} bitwise to r.\\
+\end{itemize}
+
+There is also the case 1<k<n. Here only a subset with k persons is necessary 
to reveal the secret. However, there are quickly problems with efficiency: Each 
person must know all possible combinations of his secret share with the others 
for a successful disclosure of the secret. In total there are \(\binom{n}{k}\) 
possibilities, of which every player must know \(\binom{n-1}{k-1}\).
In the worst case, the number of combinations can even grow exponentially.
+
+\subsubsection{Shamir's Secret Sharing}
+Adi Shamir is an Israeli cryptographer and a co-inventor of the RSA-Algorithm 
(Rivest-Shamir-Adleman).
diff --git a/doc/thesis/thesis.tex b/doc/thesis/thesis.tex
index 37bd0c2..1132ff9 100644
--- a/doc/thesis/thesis.tex
+++ b/doc/thesis/thesis.tex
@@ -38,6 +38,9 @@
 
 \section{Task schedule}
 \lipsum[1-5]
+
+\include{related_work}
+
 \section{Design}
 \lipsum[1-5]
 \section{Cryptography}
@@ -53,6 +56,6 @@
 \lipsum[1-5]
 
 %% Print the bibibliography and add the section to th table of content
-%%\printbibliography[heading=bibintoc]
+\printbibliography[heading=bibintoc]
 
 \end{document}

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