The sharing economy, the business of collectively using privately owned objects and services, has fuelled some of the fastest growing businesses of the past years. However, popular sharing platforms like Airbnb or Uber exhibit several drawbacks: a cumbersome sign up procedure, lack of participant privacy, overbearing terms and conditions, and significant fees for users. We demonstrate a Decentralised App (DAPP) for the sharing of everyday objects based on a smart contract on the Ethereum blockchain. This contract enables users to register and rent devices without involvement of a Trusted Third Party (TTP), disclosure of any personal information or prior sign up to the service. With increasing distribution of cryptocurrencies the use of smart contracts such as proposed in this paper has the potential to revolutionise the sharing economy.
MIT Media Lab employed blockchain to describe a decentralized personal data management system (i.e. Decentralizing Privacy) that ensures users own and control their data without authentication from a third party. In this paper, we employ a better encryption algorithm from NTT Service Evolution Laboratory to enforce the “Decentralizing Privacy”. Instead of using Proof-of-Work (PoW) for protection, we employ Proof-of-Credibility Score to improve the pervious system and analyzed attack situations.
Recently, Wi-Fi hotspots are installed at several places. However most communications are not encrypted and the illegal can use it maliciously, therefore effective breakthrough are required. We propose a solution of these problems using a new method derived from Bitcoin. This method uses Blockchain and logs of user access are saved to it. The administrators can identify illegal person and collect user's statistics. Bitcoin address can be used as encryption keys for communications. The Blockchain also provides a platform of regional applications. Furthermore, systems can cooperate with others at different places.
Marco Masoni, Maria Renza Guelfi, Gian Franco Gensini
Illegal activities prosecutable by law in the real life can be committed on the internet alike. In the healthcare domain, we refer mainly to selling of illegal and counterfeit drugs, exchange of pedo-pornographic material and marketing of stolen medical records. These illegal activities are made easier by recent developments of the Internet that medical community must be aware of: darknet and bitcoin. The first allows anonymous surfing and the last anonymous financial transactions. After discussing which healthcare areas are affected by these technological developments of the Internet and the deriving consequences, then the Authors express their opinion on what actions can be taken to protect internet community.
Michele Amoretti, Giacomo Brambilla, Francesco Medioli, Francesco Zanichelli
Location-Based Services (LBSs) build upon geographic information to provide users with location-dependent functionalities. In such a context, it is particularly important that geographic locations claimed by users are trustworthy. Centralized verification approaches proposed in the last few years are not satisfactory, as they entail a high risk to the privacy of users. In this paper, we present and evaluate a novel decentralized, infrastructure-independent proof-of-location scheme based on blockchain technology. Our scheme guarantees both location trustworthiness and user privacy preservation.
In today's online environment, people attend various kinds of activities, exhibit different digital presence, build personal digital reputations, issuing and receiving feedbacks from online communities being involved with. These diverse information sources once aggregated can provide a valuablefuture reference for personal online digital identity and credits check. The primary objective of this paper is to propose a systematic framework for aggregating online identity and reputation information, to provide a holistic approach to personal online behavioral ratings. Major contributions include: An identity aggregation mechanism based on social dependency network is proposed, a smart contract management framework referring to personal online ratings based on the aggregated digital identity, an experiment implementation based on blockchain technology, with illustrative examples and theoretical evaluations to the proposed approach.
In Mobile Crowd Sensing (MCS), the power of the crowd, jointly with the sensing capabilities of the smartphones they wear, provides a new paradigm for data sensing. Scenarios involving user behavior or those that rely on user mobility are examples where standard sensor networks may not be suitable, and MCS provides an interesting solution. However, including human participation in sensing tasks presents numerous and unique research challenges. In this paper, we analyze three of the most important: user participation, data sensing quality and user anonymity. We tackle the three as a whole, since all of them are strongly correlated. As a result, we present PaySense, a general framework that incentivizes user participation and provides a mechanism to validate the quality of collected data based on the users' reputation. All such features are performed in a privacy-preserving way by using the Bitcoin cryptocurrency. Rather than a theoretical one, our framework has been implemented, and it is ready to be deployed and complement any existing MCS system.
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.
Blockchain technology raises a multitude of legal questions that are still in early stages of discussion. While legal research is so far mainly focused on financial regulation of cryptocurrencies, distributed ledger technology in general brings considerable privacy implications. While the EU Commission expects the new General Data Protection Regulation and its technological neutrality to enable ‘innovation to continue to thrive under the new rules,’ some features of Blockchain pose questions under EU data protection principles.
Bitcoin is a crypto-currency which differs in several ways from the traditional use of money. It does not require an individual name but digital wallet IDs, which makes it more private. Bitcoin technology currently lacks protection with respect to monetary transfers, and its structure is not endorsed by the governments. Yet, understanding the concept of trust is fundamental to Bitcoin technology and digital currency economy. This paper offers a review of relevant work on cryptocurrency and trust in HCI, and critically examines its value in understanding the issues of trust in Bitcoin technology. Several limitations of the current theories and models of trust are identified, and a research framework is proposed to explore the specific trust challenges raised by the Bitcoin technology.
Digital forensics must constantly adapt to new technological developments. The advent of Bitcoin is such a development. Bitcoin represents a new model for financial transactions. In many cash transactions between strangers, the underlying model is parties-unknown/transaction-unknown. There is no ledger record of the transaction. In contrast, PayPal illustrates the parties-known/transaction-known model. An intermediary will record both items of information. Bitcoin differs from both of these models; Bitcoin uses a parties-unknown/transaction-known model. The Bitcoin block chain records the transaction, but the user’s Bitcoin address is not expressly tied to an identity. Thus, Bitcoin users enjoy pseudo-anonymity.As the recent experience with Silk Road demonstrates, there is a downside to this pseudo-anonymity. Precisely because of that feature, Silk Road served a marketplace for vendors to sell illegal narcotics, forged identifications, and other illicit goods and services. Given that danger, law enforcement authorities have a felt need to develop techniques to penetrate the pseudo-anonymity. To do so, they have turned to digital forensics experts.This article evaluates two techniques that have been proposed for this purpose. The first is traffic analysis. This technique relies on the entry nodes that users employ to access the Internet. The second is transaction graph analysis. This technique clusters transactions to identify natural chokepoints in the Bitcoin economy, that is, service islands where, for example, the user might convert Bitcoins to fiat currency. The chokepoints becomes a target for a law enforcement subpoena to learn the user’s IP address. After describing each technique, the article assesses the research conducted to date. In particular, the article reviews Alex Biryukov’s research into traffic analysis and Sarak Meiklejohn’s work with transaction graph analysis. The article applies the standards announced in Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993) to determine whether, given the available data, expert testimony based on either technique would be admissible today. The article explains that it is doubtful whether testimony based on either technique would survive a Daubert admissibility challenge. The article concludes that further research is needed to enable law enforcement authorities to effectively penetrate the pseudo-anonymity of the new parties-unknown/transaction-known model.
Enormous amounts of data are collected by hospitals, social networking systems, government agencies, and other organizations. There are huge social benefits in analyzing this data, but we must protect the privacy of the individuals in the data. The current standard definition of data privacy is differential privacy [22, 19]. In this thesis, we introduce new definitions of data privacy that can be better than differential privacy in certain ways. We first argue that differential privacy might not be strong enough in social network settings. We then introduce a zero-knowledge based definition of privacy called zero-knowledge privacy, which is strictly stronger than differential privacy and is particularly attractive when modeling privacy in social networks. Both differential privacy and zero-knowledge privacy provide strong privacy guarantees. However, for certain tasks, mechanisms satisfying these privacy definitions have to add a lot of "noise", thus lowering the utility of the released data. Thus, we introduce a new definition of privacy called crowd-blending privacy that strictly relaxes the notion of differential privacy. We demonstrate crowd-blending private mechanisms for histograms and for releasing synthetic data points, achieving strictly better utility than what is possible using differentially private mechanisms. Differential privacy guarantees the same level of privacy protection for all individuals. However, we demonstrate that some individuals may need more privacy than others. Thus, we introduce a generalization of differential privacy called tai- lored differential privacy, where an individual's privacy parameter is "tailored" for the individual based on the individual's data and the data set. We focus on a natural instance of tailored differential privacy, which we call outlier privacy: an individual's privacy parameter is determined by how much of an "outlier " the individual is. In this thesis, we also study the problem of strategy-proof voting, which is plagued by impossibility results. We take a bounded-rationality approach to this problem and consider a setting where voters have "coarse" beliefs (a notion that has gained popularity in the behavioral economics literature). In particular, we construct good voting rules that satisfy a notion of strategy-proofness with respect to coarse i.i.d. beliefs, thus circumventing the existing impossibility results.
Bitcoins have recently become an increasingly popular cryptocurrency through which users trade electronically and more anonymously than via traditional electronic transfers. Bitcoin's design keeps all transactions in a public ledger. The sender and receiver for each transaction are identified only by cryptographic public-key ids. This leads to a common misconception that it inherently provides anonymous use. While Bitcoin's presumed anonymity offers new avenues for commerce, several recent studies raise user-privacy concerns. We explore the level of anonymity in the Bitcoin system. Our approach is two-fold: (i) We annotate the public transaction graph by linking bitcoin public keys to "real" people - either definitively or statistically. (ii) We run the annotated graph through our graph-analysis framework to find and summarize activity of both known and unknown users.
Tässä opinnäytetyössä tutkittiin bitcoin virtuaalivaluuttaa, mitä bitcoin on ja kuinka se toimii. Työssä virtuaalivaluuttaa verrataan perinteisiin fiat-valuuttoihin ja pohditaan, millä tavoin bitcoin eroaa tavallisista valuutoista. Työn tutkimuskysymyksiä olivat bitcoinin käytön edut ja haitat, toimivuus maksuvälineenä sekä bitcoinin tulevaisuuden näkymien pohtiminen. Työssä tutkittiin myös, täyttääkö bitcoin rahan määritelmän vai onko se vain hyödyke. \n \nOpinnäytetyön teoriaosuus pohjatuu pääasiassa ajankohtaisiin artikkeleihin ja uutisiin sekä muutamiin bitcoinia käsitteleviin kirjoihin. Aihe rajattiin virtuaalivaluutoista vain bitcoiniin. Työssä ei perehdytä syvemmin bitcoinin teknisiin ominaisuuksiin, koska niihin perehtyminen vaatisi niin lukijalta, kuin kirjoittajalta enemmän tietoteknistä tietämystä. \n \nTutkimuksen tuloksissa todettiin, ettei bitcoin vielä aivan täysin täytä valuutan määritelmiä, eikä siitä nykyisessä muodossaan ole korvaamaan perinteisiä fiat-valuuttoja. Bitcoinin käyttö maksuvälineenä joka tapauksessa yleistyy ja käyttäjäkunta kasvaa. Toisaalta on kuitenkin vielä mahdoton sanoa tuleeko bitcoin kasvamaan merkittäväksi valuutaksi fiat-valuuttojen rinnalle, vai jääkö se pienen yleisön maksuvälineeksi.