Category Archives: Multi-party Computation

Study on the lifecycle of cryptographic algorithms 2016


This study is a natural continuation of three previous studies conducted in 2011, 2013 and 2015. The fourth version of cryptographic algorithms life cycle study published on June 9, has more than 10 authors and has 163 reference source. The 2016 report is the first one in its sequence to be written in English, because the study is unique on a global scale, and the previous versions has been of great international interest.

The foreword of the report has been written by Anto Veldre:

The Dutch DigiNotar case in 2011 demonstrated the hard choices a country faces if a PKI supporting its government’s IT systems is compromised. [..] Therefore, it was decided in 2011 to assemble a scientific task force to analyse the problems and risks that reliance on cryptography is posing on the sustainable functioning of our society.

Among the usual topics in cryptography, there is quite revealing section “Cryptographic protocols over radio connection”. For example, there the authors find that Estonian public transportation cards are vulnerable to various kinds of Denial of Service and cloning attacks:

The transportation cards in Tallinn are built on MIFARE Classic, whereas in Tartu MIFARE Ultralight C cards are used. However, even though both of the cards support cryptographic authentication, this functionality is not used. In both cases, the protocol running between the card and the reader is essentially the same, consisting of transmitting the card’s unique ID and a signature. [..] While this measure prevents unauthorised parties from issuing new cards, it does not stop the card cloning attack. [..] Cloning a card that carries a monthly ticket causes direct financial loss to the transportation service provider and must hence be urgently addressed.

Even though the ID fields of transportation cards are not writeable, other fields may be. This is for example the case with Tartu bus cards that allow e.g. the signature field to be overwritten by a standard app working on a regular NFC-capable smartphone. As a result, the card will become invalid, giving us a potential Denial of Service attack.

The report analyzes different radio frequency card technologies used for physical access control.  There are many problems – transparency issues, use of weak cryptography or no cryptography at all. The authors have also interviewed Hardmeier and G4S to study deployment issues. Some of the deployment issues revealed are quite disturbing:

Interview with a company installing NFC-based access control systems revealed that it is common practice to use same keys also in several installations, making e.g. door keys of one company work at the door of another company, too.


Cybersecurity related bachelor’s and master’s theses in University of Tartu 2015/2016


Defense committee: Dominique Unruh (chairman), Siim Karus, Vitaly Skachek, Dirk Oliver Theis, Raimundas Matulevicius.

A Cost-Effective Approach to Key Management in Online Voting Scenarios
Abstract: Since smart cards both offer reasonable prices and expose an API for development, this document evaluates different approaches to implement threshold encryption over smart cards to support an electoral process.
Student: Sergio Andrés Figueroa Santos
Curriculum: NordSecMob (MSc)
Supervisor: Sven Heiberg, Helger Lipmaa, Tuomas Aura
Reviewer: Ivo Kubjas
Defense: 02.06.2016, 09:00, Liivi 2-405

Revision of Security Risk-oriented Patterns for Distributed Systems
Abstract: In this thesis, we target the secure system development problem by suggesting application of security risk-oriented patterns. The applicability of these security risk-oriented patterns is validated on business processes from aviation turnaround system.
Student: Silver Samarütel
Curriculum: Software Engineering (MSc)
Supervisor: Raimundas Matulevicius
Reviewer: Alexander Horst Norta
Defense: 02.06.2016, 09:00, Liivi 2-405

Role Based Access Control as SecureUML Model in Web Applications Development with Spring Security
Abstract: In order to support and simplify the model-driven approach for a web application development with Spring platform, realization of a concept plugin for Eclipse IDE is proposed. This plugin supports the recognition of Spring Security notations with capability to visualize the RBAC model on top of them.
Student: Andrey Sergeev
Curriculum: Cyber Security (MSc)
Supervisor: Raimundas Matulevicius
Reviewer: Henri Lakk
Defense: 02.06.2016, 09:00, Liivi 2-405

Secure and Efficient Mix-Nets
Abstract: This thesis studies a zero-knowledge shuffle argument proposed by J. Furukawa in 2005. Firstly, we provide a more detailed and easily readable description of the shuffle and shuffle-decryption zero-knowledge protocols than in the original paper. Secondly, we provide two new characterizations of a permutation matrix and two simple modifications of the shuffle protocol that reduce the computational complexity.
Student: Janno Siim
Curriculum: Computer Science (MSc)
Supervisor: Helger Lipmaa
Reviewer: Sven Laur
Defense: 02.06.2016, 09:00, Liivi 2-405

A Comprehensive Protocol Suite for Secure Two-Party Computation
Abstract: In some scenarios, a two-party model is a better fit when no natural third party is involved in the application. In this work, we design and implement a full protocol suite for two-party computations on Sharemind, providing an alternative and viable solution in such cases.
Student: Sander Siim
Curriculum: Computer Science (MSc)
Supervisor: Dan Bogdanov, Pille Pullonen
Reviewer: Dominique Unruh
Defense: 06.06.2016, 09:00, Liivi 2-405

An improved type system for a privacy-aware programming language and its practical applications
Abstract: he goal of this thesis is to make it easier to add protection domain kinds to the SecreC language by allowing the programmer to define the protection domain kind data types, arithmetic operations and type conversions in the SecreC language without changing the compiler.
Student: Ville Sokk
Curriculum: Computer Science (MSc)
Supervisor: Dan Bogdanov, Jaak Randmets
Reviewer: Vesal Vojdani
Defense: 06.06.2016, 09:00, Liivi 2-405

Energy Harvesting in Cooperative Communications
Abstract: Energy harvesting (EH) is a crucial technology for a variety of wireless systems that have limited access to a reliable electricity supply or recharging sources. In this thesis, the design of a multiple access relay system (MARS) using EH is considered.
Student: Akashkumar Rajaram
Curriculum: Cyber Security (MSc)
Supervisor: Nalin Jayakody, Vitaly Skachek
Reviewer: Bin Chen
Defense: 06.06.2016, 09:00, Liivi 2-405

Security of Eduroam Passwords
Abstract: The University of Tartu has decided that the university’s eduroam accounts will share the same user credentials as the rest of the university’s services. This could potentially be abused by exploiting weaknesses in wireless security in order to gain access to a user’s university account. The aim of this research was to uncover any such weaknesses.
Student: Raul-Martin Rebane
Curriculum: Computer Science (BSc)
Supervisor: Dominique Unruh
Reviewer: Meelis Roos
Defense: 06.06.2016, 09:00, Liivi 2-405

Applying a Security Testing Methodology: a Case Study
Abstract: This thesis aims to describe and apply a process necessary to verify the security of a web application. A checklist of security requirements was gathered combining OWASP ASVS web application security standard and OWASP Top Ten project.
Student: Karin Klooster
Curriculum: Computer Science (BSc)
Supervisor: Meelis Roos, Margus Freudenthal
Reviewer: Kritjan Krips
Defense: 08.06.2016

Word frequency based log analysis
Abstract: The purpose of this bachelor thesis is to explore if you can use word frequency based analysis for log files and find interesting events without knowing the log structure.
Student: Karl Lääts
Curriculum: Computer Science (BSc)
Supervisor: Meelis Roos
Reviewer: Artjom Lind
Defense: 08.06.2016

Randomly Distributed PIN Code Input Layout
Abstract: This thesis examines the possibility of reducing the visual security breach of PIN code input by randomising the input field.
Student: Rain Tõugjas
Curriculum: Computer Science (BSc)
Supervisor: Tauno Palts, Kristjan Krips
Defense: 08.2016

Smart Home Hacking
Abstract: This work investigates the security and privacy issues found at an emerging smart home technology such as the CoSSMic platform.
Student: Suela Kodra
Curriculum: NordSecMob (MSc)
Supervisor: Danilo Gligoroski, Marie Moe, Dominique Unruh
Reviewer: Raimundas Matulevičius
Defense: 18.08.2016, 09:30, Liivi 2-403

Cache-Timing Techniques: Exploiting the DSA Algorithm
Abstract: This work explains some of the cache-timing techniques commonly used to exploit vulnerable software. Using a particular combination of techniques and exploiting a vulnerability found in the implementation of the DSA signature scheme in the OpenSSL shared library, a cache-timing attack is performed against the DSA’s sliding window exponentiation algorithm.
Student: Cesar Pereida Garcia
Curriculum: NordSecMob (MSc)
Supervisor: Billy Bob Brumley, Dominique Unruh, N. Asokan
Reviewer: Arnis Paršovs
Defense: 26.08.2016, 11:00, Liivi 2-403


PhD thesis: “Applying Secure Multi-party Computation in Practice”

Riivo Talviste PhD thesis: “Applying Secure Multi-party Computation in Practice”
Defense date: 14.03.2016 – 16:15 (J. Liivi 2-405, Tartu, Estonia)

Thesis supervisor: Senior Research Fellow Sven Laur, Project manager Dan Bogdanov

Professor Stefan Katzenbeisser, Technische Universität Darmstadt (Germany)
Associate Professor Kurt Rohloff, New Jersey Institute of Technology (Newark, USA)

In this work, we present solutions for technical difficulties in deploying secure multi-party computation in real-world applications. We will first give a brief overview of the current state of the art, bring out several shortcomings and address them.
The main contribution of this work is an end-to-end process description of deploying secure multi-party computation for the first large-scale registry-based statistical study on linked databases. Involving large stakeholders like government institutions introduces also some non-technical requirements like signing contracts and negotiating with the Data Protection Agency.


Data Protection Inspectorate allows to process personal data in privacy-preserving manner


In Estonia, the Ministry of Education and Science keeps track of students and the Tax and Customs Board keeps track of working (by tracking income tax payments). If data scientists could access these databases, they could find the correlation between working during studies and not graduating in time. However, this data cannot be shared because of the Personal Data Protection Act and the Taxation Act (not to mention the relevant EU regulation). This prevents such studies from being performed.

Personal Data Protection Act actually permits processing of personal data for research purposes (see § 16), although data mining in privacy-preserving manner might have some advantages.

We used the Sharemind Application Server with its analytics package Rmind to perform the study in a privacy-preserving way. The privacy-preserving solution was checked by the Estonian Data Protection Inspectorate. Their response was that our solution does not process Personally Identifiable Information (PII) in the meaning of the law.

For actual privacy of the study the institutions are required to audit the code which is being run on the Sharemind server. In this case Tax and Customs Board had a person having skills and willingness to audit the code:

Furthermore, the Tax and Customs Board reviewed Sharemind’s source code to ensure that everything is performed according to the study plan.

The  findings of the study:

Our study showed relations between higher education and higher income, but we found no relation between working during studies and not graduating on time. Instead, it turned out that Estonian students of all fields work an equal amount. Also, our data showed clearly the reduction of employment during the financial crisis in 2008.


Cybersecurity related bachelor’s and master’s theses in University of Tartu 2014/2015


An Empirical Comparison of Approaches for Security Requirements Elicitation
Abstract: Security Quality Requirements Engineering (SQUARE) and Security Requirements Elicitation from Business Processes (SREBP). This thesis compares the two methods based on an empirical case study of the Estonian Football Association. The elicited security requirements are categorized and the completeness of their coverage is compared.
Student: Karl Kolk
Curriculum: Cyber Security (MSc)
Supervisor: Raimundas Matulevicius
Reviewer: Fredrik Payman Milani
Defense: 26.02.2015

The Analysis and Design of a Privacy-Preserving Survey System
Abstract: This master’s thesis describes the design and business processes of the prototype of a secure survey system using secure multi-party computation. The design of the system is also described in this paper and is illustrated with a deployment model.
Student: Meril Vaht
Curriculum: Cyber Security (MSc)
Supervisor: Dan Bogdanov
Reviewer: Raimundas Matulevicius
Defense: 04.06.2015, 09:00, Liivi 2-405

Pattern Based Security Requirement Derivation with Security Risk-aware Secure Tropos
Abstract: In this master thesis we investigate the integration of a pattern based security requirement elicitation process in the goal-oriented IS development. By performing this integration we aim at providing a process that enables the elicitation of security requirements from Security Risk-aware Secure Tropos (RAST) models. The contribution of this thesis are five Security Risk-aware Patterns expressed using RAST.
Student: Atilio Rrenja
Curriculum: Software Engineering (MSc)
Supervisor: Raimundas Matulevicius
Reviewer: Peep Küngas
Defense: 04.06.2015, 09:00, Liivi 2-405.

Comparing Security Risk-oriented Modelling Languages to Manage Social Engineering Risks
Abstract: The paper applies structured approach in identification of one security risk management standard that can be applied with different modelling languages. For a more in-depth analysis in this paper considered several modelling languages as BPMN, Secure Tropos and Misuse case.
Student: Sarbar Tursunova
Curriculum: Cyber Security (MSc)
Supervisor: Raimundas Matulevicius
Defense: 04.06.2015, 09:00, Liivi 2-405.
Reviewer: Olga Altuhhova

Analysis and Mitigation of Recent Attacks on Mobile Communication Backend
Abstract: This thesis presents a broad and thorough overview and analysis of the known attacks against mobile network signaling protocols and the possible mitigation strategies. The attacks are presented in a uniform way, in relation to the mobile network protocol standards and signaling scenarios. Moreover, this thesis also presents a new attack that enables a malicious party with access to the signaling network to remove lost or stolen phones from the blacklist that is intended to prevent their use.
Student: Siddharth Prakash Rao
Curriculum: NordSecMob (MSc)
Supervisor: Tuomas Aura
Supervisor: Dominique Unruh
Supervisor: Silke Holtmanns
Supervisor: Ian Oliver
Reviewer: Arnis Paršovs
Defense: 09.06.2015, 09:00, Liivi 2-405.

Entropy Based Robust Watermarking Algorithm
Abstract: In this work, multiple robust watermarking algorithms are introduced. They embed watermark image into singular values of host image’s blocks with low entropy values. The quantitative and qualitative experimental results are indicating that the proposed algorithms are imperceptible and robust against many signal processing attacks.
Student: Lauri Laur
Curriculum: Software Engineering (MSc)
Supervisor: Gholamreza Anbarjafari
Supervisor: Mary Agoyi
Reviewer: Kaveh Khoshkhah
Defense: 09.06.2015, 09:00, Liivi 2-405.

NFC Security Solution for Web Applications
Abstract: This thesis compares existing and possible security solutions for web applications, analyses NFC compatibility for security solutions and proposes a new NFC authentication and signing solution using Google Cloud Messaging service and NFC Java Card. This new proposed solution enables authentication and signing via NFC enabled mobile phone and NFC Java Card without any additional readers or efforts to be made.
Student: Jonas Kiiver
Curriculum: Software Engineering (MSc)
Supervisor: Eero Vainikko
Reviewer: Meelis Roos
Defense: 09.06.2015, 09:00, Liivi 2-404.

Applying Estonian Internet Voting Individual Verification System to Other Electoral Systems
The current paper gives an overview of the Estonian internet voting individual verification system and introduces different ballot styles. It proposes and describes modifications to the Estonian system, so it could be used for individual verification with the introduced ballot styles and multiple elections.
Student: Joonas Lõmps
Curriculum: Informatics (BSc)
Supervisor: Sven Heiberg
Reviewer: Arnis Paršovs
Defense: 12.06.2015, 09:00, Liivi 2-404

Secure Bitcoin Wallet
This report outlines various methods and solutions targeting security concerns and aims to understand their effectiveness. It also describes Secure Bitcoin Wallet, standard Bitcoin transactions client, enhanced with various security features and services.
Student: Sevil Guler
Curriculum: NordSecMob (MSc)
Supervisor: Sead Muftic, Vitaly Skachek
Reviewer: Arnis Paršovs
Defense: 27.08.2015


PhD thesis: “Privacy-preserving statistical analysis using secure multi-party computation”


Linna Kamm PhD thesis: “Privacy-preserving statistical analysis using secure multi-party computation”
Defense date: 09.03.2015 – 16:15 to 17:45 (J. Liivi 2-404, Tartu, Estonia)

Thesis supervisor: Senior Research Fellow Sven Laur

PhD Rebecca N. Wright Rutgers University (USA)
PhD George Danezis University College London

This work focuses on how to perform statistical analyses in a way that preserves the privacy of the individual. To achieve this goal, we use secure multi-party computation. This cryptographic technique allows data to be analysed without seeing the individual values. Even though using secure multi-party computation is a time-consuming process, we show that it is feasible even for large-scale databases.


Secure multi-party computation considered for fighting VAT fraud in Estonia


In 2013 parliament mandated an invoice data annex to the VAT return whereby all firms must report all transactions with other firms exceeding 1000 Euros, with a view to checking that the buying and selling companies were declaring the same amount. Following lobbying by businesses about the accounting overhead and business secrets, the president vetoed the bill.

Sander and colleagues approached the tax and customs board with a proposal to use secure multiparty computation, and built a research prototype using Sharemind. The idea is to break VAT declarations into three shares, on servers run by the tax board, the business association, and another party, and run distributed computations to get risk scores for companies. His tests show that it’s feasible; the Estonian economy’s monthly tax returns could be processed in ten days. The remaining problem is that the tax board currently keeps its algorithms proprietary, and would prefer not to reveal them in case they get gamed; at present we don’t know how to run obscure queries in practical amounts of time. Revised legislation has now been accepted and secure MPC is on the tax board’s roadmap for the next few years. In conclusion, MPC can solve some real problems, although business processes may have to be changed.