Blokzincir tabanlı elektronik seçim sistemi modellemesi
Blockchain based e-voting system modelling
Yazar: DOĞA BARIŞ ÇAKMAK
Danışman: PROF. DR. ERTUĞRUL KARAÇUHA
İstanbul Teknik Üniversitesi / Bilişim Enstitüsü / Bilişim Uygulamaları Ana Bilim Dalı / Bilişim Uygulamaları Bilim Dalı
Derece: Yüksek Lisans, 2019
Konu: Bilgisayar Mühendisliği Bilimleri-Bilgisayar ve Kontrol = Computer Engineering and Computer Science and Control

Özet:
İnsanoğlu topluluk olarak yaşamaya başladığından beri karar alma mekanizması olarak seçimleri kullanmaktadır. Antik Yunan'da ve Roma'da seçimler yapılmasına rağmen modern anlamda ilk seçimler Kuzey Amerika'da ve Avrupa'da temsili hükümetlerin seçilmesiyle ortaya çıkmaktadır. Teknolojinin gelişmesiyle beraber geçmişten günümüze seçim sistemi teknolojileri de gelişim göstermiştir. Oyların palmiye yapraklarına işaretlenmesi gibi ilkel yöntemlerle başlayan bu süreç, günümüzde elektronik oy makinaları ve internet üzerinden oylama gibi teknolojik yöntemlerle yürütülmektedir.
Seçim sistemleri tasarlanırken demokratik kıstaslara uygun olması beklenmektedir. Günümüzde yaygın olarak kullanılan seçim sistemleri çeşitli yönlerden dezavantajlara sahiptir. Geleneksel yöntemler seçim sistemlerinin gereksinimlerini tam olarak karşılayamamaktadır. Ayrıca toplumsal barışın ve huzurun tesis edilmesi için seçim sistemlerine karşı olan güvenin yüksek olması gerekmektedir.
Gün geçtikçe önemini artıran blockchain teknolojisi, birçok alandaki süreçleri kökünden değiştirecek özelliklere sahiptir. Özellikle finansal alandaki başarılı uygulamalarından dolayı genellikle dijital para ile bağdaştırılmaktadır. Ancak bu teknolojinin sahip olduğu potansiyel bunun çok daha ötesindedir. E-Devlet'ten E-Sağlık'a birçok alanda araştırmacılar çalışmalarına devam etmektedir. Seçim sistemi teknolojilerinin de bu yeni teknolojiden etkilenmemesi düşünülemez. Bu çalışmada, blockchain teknolojisinin sağlamış olduğu faydalardan yararlanılarak, modern ve demokratik kıstaslara uygun bir model sunulmuştur.
Bu tezin ilk bölümünde yaygın olarak kullanılan seçim sistemleri incelenmiş, ardından demokratik ve modern bir seçim sisteminin gereksinimleri ortaya konmuştur. Gereksinimler belirlenirken, çeşitli uluslararası kuruluşların raporları incelenerek, demokratik ve modern bir seçim sisteminin sahip olması gereken kıstaslar göz önüne alınmıştır. Daha sonra ise blockchain teknolojisi ayrıntılı bir şekilde irdelenmiştir. İlk olarak bu teknolojinin bileşenleri ve bu bileşenler arasındaki etkileşim incelenmiştir. Ardından blockchain teknolojisinin mimarisi ve işleyişi incelenmiştir. Teknolojinin uygulama alanları ortaya konulmuştur. Uygulama alanına göre kullanılacak olan blockchain teknolojisinde ne gibi ölçütlerin göz önüne alınması gerektiği saptanmıştır.
İlerleyen bölümlerde ise mevcut seçim teknolojileri ve bunların sahip olduğu sorunlar, ilk bölümde belirlenen gereksinimlere göre ortaya konulmuştur. Ortaya konan sorunları çözecek nitelikte, blockchain tabanlı elektronik seçim modeli oluşturulmuştur. Model oluşturulurken, blockchain teknolojisinin yetersiz kaldığı alanlarda yardımcı modeller kullanılmıştır.

Abstract:
Humanity has used elections as a decision-making mechanism since they began to live as a community. Although elections are held in Ancient Greece and Rome, the first modern elections are the choice of representative governments in North America and Europe. With the development of technology, election system technologies have evolved. This process, which started with primitive methods such as marking the votes on palm leaves, is now being carried out with technological methods such as electronic voting machines and remote voting over the internet.
Elections are very critical tools for the proper functioning of democracy. Through elections, citizens transfer their power to those who will represent them. Confidence among the electorate, the state, and the candidates during this power transfer is an indispensable value. The reliability of election systems and the technologies used in these systems play a key role in creating trust among the election stakeholders.
The election process is carried out by institutions of countries in a system by determining the laws and rules. These rules determine the requirements of the electoral system be implemented and set the standards for the whole process. Each institution of a country has its own laws for the electoral processes, which makes it difficult to establish a set of universal election standards. However, when the studies of laws, practices and related institutions are examined, generally agreed and universal election standards can be determined.
Blockchain technology, which increases its importance day by day, has the features that will change the processes in many areas. It is generally associated with digital money because of its successful practices in the financial field. But the potential of this technology is far beyond that. Researchers continue their studies in many fields such as E-Government to E-Health.
Blockchain can be defined as a distributed database type in which transactions are recorded, simply by copying all the computers on the network. In Blockchain, data is stored in fixed structures called blocks. Each transaction must be encrypted before it is added to the end of the chain as a new block, and must be approved by the nodes in the network by the reconciliation mechanism. No centralized mechanism is needed to confirm the operation. It is unthinkable that the election system technologies are not affected by this new technology. In this study, a model suitable for modern and democratic criteria is presented by utilizing the benefits of blockchain technology.
In the first part of this thesis, the electoral systems which are widely used are examined and the requirements of a democratic and modern electoral system have been revealed. In determining the requirements, the reports of various international organizations were examined and the criteria that a democratic and modern electoral system should have been taken into consideration. These criteria can be listed as follows; ensuring that all voters have equal rights of one vote, no voting by proxy or another electorate, the use of secret and unregistered votes, equal accessibility to all voters, voting of an open and transparent method in the counting and processing of votes, voting of election results not being followed in any way until the end of the election process, finding a backup of the votes and re-counting, no change on the ballot papers, being controllable and reliable. Commonly used electoral technologies are paper ballots, lever voting
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machines, punched card voting, optical mark-sense voting, direct recording electronic voting, and online voting.
In the following sections, blockchain technology is discussed in detail. First, the components of this technology and the interaction between these components are examined. The main components of blockchain include cryptographic hash functions, transactions, asymmetric-key cryptography, addresses, ledgers, and blocks. Then, the architecture and the functioning of the blockchain technology were investigated. According to permission models, it is divided into two types, open and private. The consensus methods and the differences in these methods have been revealed. The reasons why soft forks happened and how to solve them were discussed. Then the causes and consequences of hard forks were examined. Smart contracts and the benefits and implementation challenges have been demonstrated. It has been determined what kind of criteria should be taken into consideration in the blockchain technology to be used according to the application area.
In the following section, current election technologies and their problems are presented according to the requirements set out in the first section. The biggest weakness of the paper ballots is the counting of the votes. As in all other vote-counting procedures, the delegation that counts the votes must be representatives of opposing parties, and if a party becomes a majority in this committee, it may affect vote counts in their favor. Lever voting machines do not have any backups of votes. The biggest problem with, punched card voting is that it is not guaranteed to drill a neat hole on the cards. In the optical mark-sense voting, voters must make the marking required by the optical reader manufacturer so that the votes can be read correctly by the optical sensors. Direct recording electronic voting and the biggest concern on online voting is the security problem.
Finally, the blockchain based electronic election model, which will solve the problems, is presented and the advantages and disadvantages of this model are examined. In developing a blockchain based e-election model, election requirements, actors in the election process, the duties and responsibilities of the actors and the performance criteria that the blockchain technology should provide are taken into account. The model consists of three stages: Installation, Voting, Counting of Votes and Announcement of Results. During the installation phase, the regulatory body installs the blockchain network and other systems that will be required. Blockchain records assets such as voter, party and candidate, encryption keys to the network. In the voting process, voters are elected to vote by means of client applications. In this step, the votes are signed in an unknown and secure manner by the blind signature method. Votes, regulatory body and political parties through the network nodes are confirmed and encrypted in the chain is recorded. In the stage of counting of votes and announcement of results, the encrypted votes in the chain shall be resolved in a transparent manner. At this stage, voters can check whether their votes are counted or not. After the counting process is completed, the results are announced.
With the model developed, it was seen that the election requirements mentioned at the beginning of this study were met. However, there are some parts of the model that are open to development. The presented model is very safe due to the advantages of blockchain technology. However, this situation involves the processes after the votes are written to the chain. The security of the client machines in the model is the biggest problem. The backup of the votes is available on all nodes that are joined to the network. Therefore, technically no other backup is needed, but it is unlikely for the
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public and stakeholders to fully understand the blockchain technology. In this case, the confidence in the proposed model may be reduced. In order to prevent this, voting papers digitally signed by the voting machines can also be included in the election process. Tens of millions of voters vote in the general elections. This number may also rise to hundreds of millions in some countries. It is important to make sure that the blockchain technology can handle this heavy throughput load.