Sharif Digital Repository

This research deals with one of the current issues in the world and in Iran, which is named the field of cryptocurrencies. Domain that is managed decentrally due to the use of blockchain platform. This decentralization has caused different challenges (security problems, disruption of economic governance, etc.) for governments and has created different advantages and disadvantages for each country. This study seeks to investigate how Iran is facing the challenges in the field of cryptocurrencies. In this research, three main questions have been asked to determine the situation of Iran in the field of cryptocurrencies. In the first question, what are the policies of Iran is questioned and then... 

Managing health data and providing remote treatment services to patients has always faced security and privacy challenges. Because of the importance and sensitivity of this data, the use of centralized networks such as cloud space and trustin a cloud server can be dangerous, due to the lack of complete trust in the cloud server. To prevent the threats of centralized systems, we provide a decentralized blockchain-based system in which miners, in addition to authenticating physicians and patients, are also responsible for searching encrypted data and all user activities can be tracked in the distributed ledger. The proposed scheme preserves data privacy, and there is no need to trust a server.... 

Blockchain systems are considered a subclass of distributed systems and have drawn a lot of attention from academia in recent years. The deployment of these systems in various contexts has been the focus of extensive studies. Because of their design, which places a strong focus on security and decentralization, blockchain systems have some challenges. The most prominent challenge is the one that involves scalability. A blockchain's scalability refers to its capacity to achieve a target throughput and solid performance in confirming transactions with an ever-increasing workload or number of nodes in the network. A solid performance suggests that the blockchain system can sustain its... 

Payment channel networks (PCNs) are a promising technology to improve the scalability of cryptocurrencies. Users can send instant and almost free transactions via payment channel networks and, at the same time, enjoy the security guarantees of Blockchains. In order to open a mutual payment channel, two users should send a ``channel creation" transaction to the underlying Blockchain. Through this transaction, two parties deposit some money on the Blockchain. This money, which we call the channel's capacity, can be used to send off-chain transactions between the two users. After the channel creation, the channel-holders can send each other off-chain transactions by forwarding the money back... 

Cryptocurrencies (cryptos), as a new type of money, are considered a medium of exchange, an investment asset, and a hedging tool in today's world. In 2008, bitcoin as the first cryptocurrency was introduced, which has survived through recent years and has gained more and more popularity every day. Cryptos are one of the first applications of blockchain, the technology that many expect to revolutionize the future world in different ways. We aim to investigate what affects the bitcoin price, based on artificial intelligence and, in particular, machine learning. First, we find features impacting bitcoin price via a thorough investigation of the literature. Then, applying machine learning and... 

In communications systems, coding is used to combat channel errors. The redundancy introduced by coding enables the detection and/or correction of errors occurring in the channel. In addition to communications systems, coding is also beneficial in various other systems such as distributed storage systems and blockchain systems to cope with node failures, data erasures, and adversarial behaviors attempting to modify information. In existing applications of coding, it is generally assumed that the encoding operation is performed correctly and without errors, and errors are applied to the encoded data. In recent years, applications have emerged where the assumption of error-free encoding is not... 

In recent years, the high energy consumption of blockchain technology has led to the creation of major problems such as more greenhouse gas emissions and additional pressure on the power grid. In this regard, the emerging technology of flow batteries for large-scale electricity storage might be a suitable choice to overcome both problems. In this research, a novel interdisciplinary methodology has been developed to optimize the flow battery design in different scenarios of energy systems with blockchain mining electricity demand. In this methodology, a new electrochemical model was developed for the vanadium redox flow battery with a no-mixing design, and its results were validated on... 

The emerging blockchain technology has introduced a new approach in today's industry, creating new opportunities in technical, financial, and economic domains. With the emergence of blockchain-based platforms such as Ethereum and the capability of smart contracts, the possibility of creating decentralized systems has arisen. One of the most popular decentralized systems in the realm of finance is crowdfunding platforms that assist technical and academic projects in need of capital for industrialization. Startups or research-academic projects secure the necessary funding by selling initial offering tokens to both small and large-scale investors. In this research, we aim to present an... 

The purpose of this thesis is to improve the protocols for recording and transmitting medical data in terms of security and performance using blockchain technology. The approach we take in this Thesis differs in three respects from most articles written in this field. The first is that unlike those who look at the blockchain as a black box and take advantage of only its positive features, we consider the details and challenges it creates for us and solve them in order to use it. The second important point is to justify the use of blockchain in this design. It can be seen in many designs that the use of this technology is useless according to their model and goals. Finally, one of the most... 

Voting has been considered as one of the principal of democracy which by this, people can announce their convictions and ideas officially. E-voting is a method of online voting based on cryptographic mechanisms. E-voting schemes by keeping voters' privacy safe and providing security requirement same as verifiability, fairness, coercion resistance, receipt freeness, undeniability, and eligibility has been noticed in recent years. Security of many presenting schemes is based on existence of trusted third party that plays an important role in process of getting and counting votes. Also, some of security problems which are in this scheme, originated from centralization and generic trust of third... 

In the light of rapid advancement in renewable energy technologies, they become an appropriate way to supply energy demands with lower costs. It also gives them the chance to earn money by selling surplus energy to other energy consumers. The coordination of different energy types and the ability of energy conversion, facilitates the rising of new energy prosumers called “Smart Energy Hub(SEH)”. This thesis proposes a model of energy trading among SEHs. The model consists of SEHs, energy utility grids, energy consumers and aggregator. In this model, aggregator aggregates between SEHs, energy consumers and utility grids in order to maximize its profit. Bilevel optimization problem has been... 

Lightweight clients are a type of blockchain users who do not store all the blocks in the blockchain due to limited resources. These users store only a small part of each block and when needed, request transactions from full nodes that store the entire blockchain. These users have no role in block validation and only want to receive transactions related to their addresses with proof of the inclusion in the block from full nodes.Since light clients rely on full nodes for receiving transactions, their privacy against full nodes is important. The current implementation of Bitcoin uses Bloom filters for privacy, but this offers very little privacy to the users.In this thesis, we study the... 

Population and urbanization increase, intra-city travel and the use of private cars have created problems such as traffic, higher fuel consumption and air pollution. One of the approaches to deal with this phenomenon, which has been in center of attention in recent years due to the growth of technology and development of ride-hailing platforms on mobile phones, is using shared vehicles and travel sharing.The assignment problem in ride-sharing is a group of VRP problems and is classified as an NP-hard problem. Due to the high volume of demand from passengers and supply from drivers, as well as the need for fast response to reduce waiting time for passengers and drivers, there is a need to... 

To update Blockchains, a consensus protocol must be used to verify the integrity of registered transactions by users. Bitcoin, as the largest Blockchain network, uses a Proof-of-work mechanism to reach consensus and rewards users for doing so. This will lead to the use of costly hardware to execute heavy processing commands with a lot of energy loss. Different groups have since proposed different mechanisms for reaching consensus without costly processing. The idea we present here is that we first define a general chance variable for each miner, and the miner has to wait a certain amount of time accordingly and then be able to generate the block. Chance variables are public, so other members... 

Vaccinating the global population against Covid-19 is one of the biggest supply chain management challenges humanity has ever faced. Rapid supply of Covid-19 vaccines is essential for successful global immunization, but its effectiveness depends on a transparent supply chain that can be monitored. In this research, we have proposed an approach based on blockchain technology, which is used to ensure seamless distribution of the Covid-19 vaccine with transparency, data integrity, and full traceability of the supply chain to reduce risk, ensure safety, and immutability. Without a proper mechanism to track and guarantee the authenticity of vaccines, all involved members, including governments,... 

The ability of blockchain to record transactions and automatic execution feature in smart contracts, increase the speed of the supply chain and reduce unnecessary delays. A blockchain-enabled supply chain is more dynamic and responds to changes faster. This makes many processes more efficient in the supply chain. Supplier performance evaluation is an essential field in Supply chain management. At any time, by recording real-time data through smart contracts in the blockchain, it is possible to see the supplier’s performance in different aspects according to all the information recorded up to that moment. This research investigates the use of smart contracts and blockchain in solving supply... 

Supply Chain (SC) systems stand at the cusp of a transformative era, thanks to the synergistic integration of Blockchain Technology (BT) and the Internet of Things (IoT). This confluence promises a plethora of benefits, encompassing heightened data protection, unparalleled transparency, robust fraud prevention mechanisms, meticulous traceability, and substantial financial efficiencies. However, the technological landscape is still in its embryonic phase, leading to a pronounced knowledge void and a palpable uncertainty in the realm of platform selection for SC systems. The challenge is further compounded by the intricate web of criteria, often with overlapping and interdependent facets.... 

Emergence of crypto-currency and blockchain technology revolutionize supply chain processes. In addition, customer needs for more information on products or services from origin to destination, highlights the necessity of transparency, originality and traceability in supply chains. This research is aimed to develop a blockchain based system ascertaining supply chain transparency and originality. To this aim, a joint pricing and closed-loop supply chain network design problem is selected as a good platform to implement it. Due to increasing concerns on environmental issues and maximizing job opportunities, sustainability is also considered in the proposed problem. To ascertain transparency...