Bitcoin ilk merkezi olmayan, eşler arası ve en çok bilenen kripto paradır. Kripto paralar bir çeşit dijital paralar olup sanal para olarak da adlandırılır. Bitcoin 2009 da kullanılmaya başlandı ve bu tarihten itibaren büyük bir ilgi gördü. Geliştiriciler ve kullanıcılar tarafından büyük yatırımlar ve büyük katkılar sağlandı. Paranın yönetilmesi için bir merkeze bağlı olan günümüzde kullanılan paraya alternatif olarak kullanıma sunuldu. Fakat bu süre zarfında Bitcoin birçok problemle karşılaştı. Bunlara rağmen yaklaşık yedi senede çok büyük bir pazara sahip oldu. Bitcoin'in başarılı çıkışından sonra farklı amaçlara hizmet eden bir çok alternatif kripto para geliştirildi. Geliştiriciler Bitcoin'in bir çok farklı versiyonlarını geliştirdi. Bunlardan bazıları, Litecoin gibi Bitcoin'in kaynak kodunu kullanarak geliştirildi. Bazı kripto paralar Zcash, Ripple, Peercoin Bitcoin'in mahremiyet, ölçeklenebilirlik, enerji tüketimi gibi farklı eksikliklerinin üstesinden gelmek için geliştirildi. Bazıları ise, Ethereum, Namecoin, Colored Coin gibi, blockchain denen herkese açık kayıt sistemi fikrini kullanarak yenilikçi fikirler getirdi. Her geçen gün yeni kripto paralar kullanıma hazır hala getiriliyor ve bu teknoloji gelecekte şu anda kullanılan paranın yerini alacağı tahmin ediliyor. Bu tezde, Bitcoin ve alternatif kripto paralar tartışıldı ve mahremiyet, ölçeklenebilirlik, ticari işlem değiştirilebilirliği ve şu ana kadar maruz kaldıkları, savunmasız oldukları ataklar açısından karşılaştırıldılar. Gelecekteki durumları tartışılarak, gelecekte yapılacak işlerin planı yapılarak bu çalışma tamamlanmış oldu.
Kibin Lee, Joshua I. James, Tekachew Gobena Ejeta, Hyoung Rae Kim
Cryptocurrency, and its underlying technologies, has been gaining popularity for transaction management beyond financial transactions. Transaction information is maintained in the block-chain, which can be used to audit the integrity of the transaction. The focus on this paper is the potential availability of block-chain technology of other transactional uses. Block-chain is one of the most stable open ledgers that preserves transaction information, and is difficult to forge. Since the information stored in block-chain is not related to personally identify information, it has the characteristics of anonymity. Also, the block-chain allows for transparent transaction verification since all information in the block-chain is open to the public. These characteristics are the same as the requirements for a voting system. That is, strong robustness, anonymity, and transparency. In this paper, we propose an electronic voting system as an application of block-chain, and describe block-chain based voting at a national level through examples.
Today, most people have heard of Bitcoin, but few have truly understood the concept and its functions. The phenomenon causes strong emotions and the opinions are divided. Some think that Bitcoin will revolutionize the financial system, while others lean towards the possibility that it is merely a short-lived trend. The aim of this report is to analyze if Bitcoin has the qualities required of a substitute for the domestic currency. The study is based on money’s necessary functions and the variables that cause an individual to go as far as abandoning their domestic currency. Even though Bitcoin is a functioning alternative, an analytic comparison with the American dollar showed that bitcoin cannot yet compete with the qualities of dollars, much due to the lack of expansion. The report indicates that in the long run Bitcoin’s characteristics can develop today’s monetary system and create considerable changes in the future.
Distributed consensus (aka Byzantine agreement [Pease, Shostak & Lamport, 1980]) is one of the fundamental problems in fault-tolerant distributed computing and cryptographic protocols. It requires correct participants (parties) to reach agreement on initially held values despite the arbitrary behavior of some of them, with the additional requirement (known as Validity) that if all the correct participants start off with the same value, then that must be the decision value. The problem has been studied extensively in both the unconditional setting (where no assumptions are made about the computational power of the adversary) and the cryptographic setting, and efficient (i.e., polynomial-time) solutions exist tolerating the optimal number of misbehaving parties and running in the optimal number of rounds, on networks with pairwise authenticated channels. In many interesting scenarios, however, such as "peer-to-peer" networks, where parties come and go as they please and there are no prior relations among them, such infrastructure (pairwise authenticated channels, public-key infrastructure) is unavailable, thus raising the question whether anything "interesting" can be achieved. In this talk we answer this question in the affirmative, presenting two new probabilistic consensus protocols based on "proofs of work" (POWs, aka "moderately hard functions," "cryptographic puzzles" [Dwork & Naor, 1992]), the technology underlying Bitcoin, the first and most popular decentralized cryptocurrency to date. (In Bitcoin, POWs are implemented using the SHA-256 cryptographic hash function, by finding preimages that produce values in a given smaller domain.) In more detail, we first extract and analyze the core of the Bitcoin protocol, which we term the Bitcoin backbone, and prove two fundamental properties of its "blockchain" approach which we call "common prefix" and "chain quality." The consensus protocols can then be built as applications on top of the backbone protocol, with the Agreement and Validity properties following from common prefix and chain quality, respectively. The first protocol works assuming the adversary's hashing power is bounded by 1/3 of the network's total hashing power. The second consensus protocol is more elaborate, relies on the notion of robust transaction ledgers, which capture the essence of Bitcoin's operation as a cryptocurrency, and works assuming the adversary's hashing power is strictly less than 1/2.
Botnets, in other means zombie computers that await for instructions to execute, are the greatest threat in the internet today. They are one of the leading sources of online crime. Criminals are able to take advantage of using botnets and threaten online businesses, organizations or any entity in the internet. Criminals design and implement botnets in a complex way in order to hide their identities. Most notably the fact that criminals build command-and-control (C&C) infrastructures to manage their botnets. A botnet command-and-control mechanism (C&C) can be designed in various ways. The key principle behind designing a C&C mechanism is anonymity. Hence, criminals can propagate their instructions to botnets without revealing their identities. Since every new C&C mechanism increases the bar of anonymity, it is getting harder to trace and analyze botnets. In this thesis, we designed and implemented a C&C mechanism, btc-botnet, that runs over Bitcoin network. Btcbotnet has significant features over existing C&C mechanisms such as anonymity and resistance by its nature. We built a library that allows to use Bitcoin network as an underlying infrastructure for C&C mechanism. We evaluate our work and show that its feasibility in terms of metrics such as response time, confirmation time and fees.
Blockchain is a new type of shared ledger for distributing and keeping consensus on what constitutes a true state of a system. The implications of the technology, i.e. enabling almost trustless transactions between market participants, is a revolutionary idea, especially to financial markets. The Swedish fund market, being a fragmented and in some cases inefficient system of intermediating actors, is a potential use case for the new technology of blockchain. This report reviews and presents the technology underlying the new blockchain phenomenon, and its potential application to the Swedish fund market with a specific focus on the possible new trust dynamics in such a market. Blockchain could, by removing some of the inter-participant risks, disintermediate the communication between market actors in the Swedish fund market, possibly enabling a cost reduction related to fund unit administration and order handling.
The last forty years has seen both unprecedented loss of natural tropical forests and innovation in forest governance, implying that more work is needed to refine the theory and practice of forest governance in a carbon challenged world. This dissertation used the Tanzanian case of the recently introduced international program to reduce emissions from deforestation and forest degradation (REDD+) to empirically explore the design and performance of emerging forest governance arrangements. Drawing from extensive ethnographic field data (participant and non-participant observations, oral histories, key informant interviews, focus group discussions, documentary reviews and household surveys) conducted over five years (2009-2014), with actors in Kilwa and Lindi Districts in South-Eastern Tanzania, this dissertation makes several contributions organized into three substantive chapters. The first chapter, entitled “Negotiating forests under the REDD+ context in South-Eastern Tanzania” provides descriptions of how local forest residents creatively deploy the use of modern technologies of mobility (cellphones and motorcycles) and the discourses of decentralization, democracy and participation to continue performing otherwise banned cultural-ecological practices of shifting cultivation and wood extraction blamed for the reported forest disappearance. The second chapter, entitled “Deliberative democracy and the making and unmaking of illegitimate forest institutions” exposes and analyzes the paradoxical eruption of REDD+ resistance despite the adoption of participatory and democratic processes in making and implementing REDD+ interventions arguing that the adoption of deliberative democratic processes remain alien to local residents and has resulted in the production of legally legitimate but democratically illegitimate and often unfair forest institutions pushing local residents to opt for resistance as alternative mechanisms for contesting the introduced forest institutions. The third chapter, entitled “Mismatched: why do REDD+ payments fail to avoid deforestation in human dominated miombo ecosystems?” challenges and expands on the application of recently introduced carbon payment as an innovative financing scheme for encouraging adoption of sustainable forest management practices in the tropics. I argue that when those inadequate payments are aligned to seasonality of cultural-ecological practices causing forest change and if injected at the appropriate spatial scale (individual and/or community) where decisions affecting forests are made, they have a greater chance of achieving intended impacts.
Open access
Conservation, Biodiversity, and Resource Management
In this paper we investigate the concept of cancelable biometrics and propose a new scheme for user authorisation providing anonymity based on privacy-preserving computations on sets. We define a problem called (t;n) -Threshold Subset Problem and apply it to a biometric-based security system. Our solution implements biometric template protection based on one-way transformations and Bloom filters. Users authentication data is stored in form of a whitelist and the authorisation process is based on a zero-knowledge proof approach. Using oblivious polynomial evaluation (OPE) a legitimate user is able to recreate a secret polynomial and answer the challenge send by a verifier. We assume that biometric data can be acquired and digitized to the form of a vector representation.
This paper presents two case studies for the delivery of wastewater servicing solutions: one in Ontario, Canada and the other in Gujarat State, India. In each case a decentralized small diameter gravity sewer wastewater collection and treatment system was implemented for servicing residential development—with some interesting differences and similarities. The first case is a small private mobile home park in Eastern Ontario under a Ministry of Environment Order to address failing on-site septic systems. The Municipality was obliged to take over operation of the on-site systems; however, there were not adequate funds available to rectify the failing systems. A group of local companies initiated the process to find and deliver a solution featuring a Design-Build-Operate-Finance model for a private communal sewage system showcasing advanced wastewater technology. The second case is a rural Indian village without wastewater servicing infrastructure, but with considerable political incentive to implement a new low-maintenance communal sewage system funded through a government-regulated corporate social responsibility program. The completion of the project will enable this village to be cited as the first open defecation free village in Gujarat State; however, success will ultimately be measured by long-term user buy-in. Each case study will discuss the project context; implementation of design, approvals and construction; financial and delivery model; and key success factors and lessons learned. Both case studies will highlight how using unconventional technology and innovative funding enabled the implementation of decentralized wastewater solutions in each situation
Bitcoin on vuonna 2009 julkaistu vaihdannan väline, jota hallinnoidaan niin kutsutussa vertaisverkossa. Bitcoinin vahvuuksia ovat järjestelmän ulottuvuus, siirtojen edullisuus, helppokäyttöisyys, turvallisuus ja riippumattomuus keskusjohtoisista taloudellisista instituutioista. Bitcoin ei kuitenkaan ole virallinen valuutta, eikä sitä tätä tutkielmaa kirjoittaessa ole juurikaan säännelty eri valtioiden toimesta. Sääntelyn puutteen voidaan katsoa olevan Bitcoin -järjestelmän heikkous, sillä se aiheuttaa epävarmuutta ja epäjohdonmukaisuutta viranomaisten keskuudessa. Vero-oikeudellisesta näkökulmasta sääntelyn puute synnyttää verovelvollisille, eli Bitcoinien käyttäjille riskin odottamattomasta verokohtelusta. \n \nTämän tutkielman pääteemana on Bitcoin -järjestelmän taloudellinen ja verotuksellinen luonne nykyisen kotimaisen tuloverolainsäädännön valossa. Tutkimusmenetelmänä käytetään tietyin painotuksin oikeusdogmaattista ja monitieteellistä näkökulmaa. Soveltuvan oikeuskäytännön rajallisuudesta johtuen keskeisimpinä lähteinä toimivat tuloverolainsäädäntö, lainvalmisteluasiakirjat, viranomaisohjeet ja oikeuskirjallisuus. Tutkielmaa täydennetään taloustieteellisillä lähteillä ja Bitcoin -järjestelmään liittyvällä merkittävimmällä kirjallisuudella. \n \nTutkielman valossa Bitcoin -järjestelmän taloudelliset luonteenpiirteet suhteessa kotimaiseen tuloverolainsäädäntöön näyttäisi asettuvan lähelle omaisuuden luovutusvoittoja ja -tappioita koskevia lainkohtia. Koska Bitcoin -järjestelmän arvo syntyy yksittäisissä vaihdantatapahtumissa subjektiivisesti, ei Bitcoinista saatavaa tuloa tai tappiotakaan voida arvioida sen perusteella, mikä Bitcoinin arvo on suhteessa viralliseen valuuttaan jossain toisessa vaihdantatapahtumasta. Nykylainsäädännön valossa Bitcoin tulisi määritellä omaisuudeksi tai toissijaisesti rinnastaa sen kohtelu omaisuuden luovutusvoittoverotukseen. Näin tuloverotuksessa päästäisiin mahdollisimman lähelle Bitcoinin taloudellisia realiteetteja. Tällainen Bitcoinin tuloverotuksellinen kohtelu vastaisi lisäksi verovelvollisen todellisia maksukyvyn muutoksia ja täyttäisi hyvän verojärjestelmän edellytykset verotuksen oikeudenmukaisuudesta ja neutraalisuudesta.
We need to shift our perspective of blockchain, from just the programmable ledger, to a networked infrastructure of computing machinery. Doing so, we could easily visualize how computer programs will operate over this new infrastructure, which is presently being used for transaction validations. We cannot take the cloud computing analogy literally because the blockchain infrastructure can’t replace cloud computing completely. Although, it unbundles and democratizes cloud computing. Thus, companies and individual consumers can soon keep their data in distributed cloud network based on highly secure blockchain technology.
This article analyses aspects of public financial decentralization in Romania, enlightening major problems in public money allocation at county’s administrative level. Actual public finance law and state budget law allow inefficiency and inequity in local public money spending. This happens, in our point of view, because of many rules, criteria and computations missing economic fundamentals and which skip state’s principal objective: to insure citizens’ welfare by providing public goods and services. Our research finds which Romanian counties have difficulties to satisfy local public needs, by confronting financial decentralization level, economic development and public expenditures.
In recent years, sponge city construction has aroused widespread concern; the financing mode of the sponge city also has the discussion value due to its important safeguard function to smoothly carry on the construction of sponge city. The financing mode of the sponge city is divided into two parts in this paper, including the financing mode in Japan and America with the developed capital market, and the financing mode & experience in Germany whose capital market is less developed but has the complete market economy system, and introduces significance to our country brought by the successful experiences of the financing mode of the overseas -the decentralization of the local government bond issuance right, the establishment of the effective supervision mechanism; the flexible use of bank loans, supported by the preferential fiscal policy; the establishment of the government credit rating system, perfect the credit information publicity system; charge to the residents of the installation fee of the sponge city, relief the cost to who build the devices by themselves.
This dissertation comprises three empirical essays in political economy. The first essay analyzes the implementation of a French social program by subnational governments following a decentralization reform. Using program implementation data, it shows that local political environments strongly influence implementation decisions after decentralization, and that decentralization results in an overall tightening of benefits. The second essay reports the results of a conjoint field experiment involving German welfare offices. Using random assignment of cues about ethnicity and other characteristics in requests to welfare offices, it is shown that putative non-German applicants receive replies at the same rate as putative Germans, but are disadvantaged in terms of the substantive quality of responses. This suggests that minority populations do experience discrimination when attempting to access social benefits. Finally, the third essay uses micro-level voter file data from Illinois to measure whether property tax limitations reduce participation in local elections. In contrast with prior research, results from panel regressions with matching adjustments suggest that tax limitations do not affect political participation negatively. Together, these essays contribute to our understanding of public finance and social policy in contexts characterized by multi-level governance.
In the early twentieth century British colonial authorities continued their efforts to decentralize the governance and financial system of British India by providing greater administrative and financial authority to provincial governments, which required delineation of powers and the financing of the government of British India and the provincial governments. Governor-General of India, Lord Curzon tried to escape the disadvantages of the "Ripon scheme" and introduced a scheme of "quasi-permanent nature", based on three principles. The basic idea of the scheme was to raise the interest of the provinces to increasing of their income. The lack of success of the reforms led to the establishing by Edward VII in September 1907 of "Royal Commission on Decentralization of India", which was to examine the situation on the ground and then to make suggestions. In February 1909 the Commission submitted a report, which laid out the arguments both in favor of centralization of governance and in favor of decentralization. In order to enhance the decentralization they proposed measures for increasing of the powers of provincial governments and authorities subordinate to administrative units, governance of public services on a wide range of issues, primarily "provincial" and "subordinate" parts of the Indian Civil Service, the police, as well as medical, sanitation and so on. Particular emphasis was placed on the need to develop local government throughout India, particularly in rural areas. The most important role among them was assigned to panchayati. They envisaged the establishment of self-government at the district level and at the lowest level - a village or a group of villages. Accordingly, the proposed redistribution of competences between different levels of government and self-government. To implement the changes, the commission recommended to redistribute sources of financing government bodies at each level and discussed specific taxes thoroughly enough. They also mentioned some situations when the income did not cover the costs of provinces, districts and villages. The report revealed the need for changes in the cost structure of different levels of authorities. The article suggests some measures for implementation of recommendations of the Commission, the assessment of its activities by a number of researchers and sources, and makes a brief conclusion.
Open access
Social and Economic Development in India
Politics and Conflicts in Afghanistan, Pakistan, and Middle East
Proof-of-work is a central concept in modern cryptocurrencies and denial-ofservice protection tools, but the requirement for fast verification so far has made it an easy prey for GPU-, ASIC-, and botnet-equipped users. The attempts to rely on memory-intensive computations in order to remedy the disparity between architectures have resulted in slow or broken schemes. In this paper we solve this open problem and show how to construct an asymmetric proof-of-work (PoW) based on a computationally-hard problem, which requires a great deal of memory to generate a proof (called a ”memory-hardness” feature) but is instant to verify. Our primary proposal, Equihash, is a PoW based on the generalized birthday problem and enhanced Wagner’s algorithm for it. We introduce the new technique of algorithm binding to prevent cost amortization and demonstrate that possible parallel implementations are constrained by memory bandwidth. Our scheme has tunable and steep time-space tradeoffs, which impose large computational penalties if less memory is used. Our solution is practical and ready to deploy: a reference implementation of a proof-of-work requiring 700 MB of RAM runs in 15 seconds on a 2.1 GHz CPU, increases the computations by a factor of 1000 if memory is halved, and presents a proof of just 120 bytes long.
Money laundering can be defined as any act or attempted act to conceal or disguise the identity of illegally obtained proceeds so that they appear to have originated from legitimate sources (Money Laundering, 2016). It is difficult to determine the magnitude of money laundering because these illicit financial flows remain hidden (Schott, 2006). A report issued by the United Nations Office on Drugs and Crime (UNODC) quoted that the total of all criminal proceeds amounted to $2.1 trillion in 2009. The study also shows that “Less than 1 percent of global illicit financial flows are currently seized and frozen” (Pietschmann & Walker, 2012). This is concerning because money laundering not only enables the operation of criminal organizations such as drug and human traffickers but can also significantly distort the economies in which they enter.\nThe Financial Action Task Force (FATF) is an inter-governmental policy-making body that has helped to promote anti-money laundering efforts since its formation in 1989. It has issued 40 recommendations to fight money laundering and nine special recommendations to combat terrorist financing which have been adopted by 32 countries (About - Financial Action Task Force, 2016). Unfortunately, implementing these strategies has proved to be difficult for both developed and lesser developed countries. According to a study conducted by PricewaterhouseCoopers in 2016, “over the last few years, in the U.S. alone, nearly a dozen global financial institutions have been assessed fines in the hundreds of millions to billions of dollars for money laundering and/or sanctions violations" (PricewaterhouseCoopers, 2016). It stands to say that if financial institutions are having difficulties implementing frameworks to prevent and detect money laundering, then our enforcement agencies are unable to adequately address the issue as well.\nA new hurdle that enforcement agencies have had to face is the emergence of Bitcoin, as well as other cryptocurrencies, that can be described as “a digital currency and online payment system in which encryption techniques are used to regulate the generation of units of currency and verify the transfer of funds, operating independently of a central bank” (Swan, 2015). Being an often unrecognized currency, many banks and financial institutions have not had to worry about modifying their compliance programs. The biggest benefit of cryptocurrencies to money launderers is its decentralized nature. There is no governing authority, as members of the network handle issuances and payments. Once a disruptive technology, Bitcoin is beginning to lose momentum for a number of reasons and some its strongest proponents are now referring to it as nothing more than an experiment. The purpose of this paper is not to examine Bitcoin, but rather its underlying technology that has been found to be the actual value: blockchain. After providing a brief overview of the technology and the hurdles that financial institutions face when implementing anti-money laundering compliance programs, the possible ways in which blockchain can help alleviate these difficulties will be examined.