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The Blockchain is a technology which has the capabilities to change the way, the world operates. As promising as this may be, there are still many challenges which do not exist or are way simpler to solve in conventional software solutions. Services which are offered over the blockchain suffer from so called Block-confirmation-times where the customer simply has to wait till the transaction is confirmed. In this paper possible solutions to that problem will be examined and challenges that arise from the specific criteria of the Ethereum Blockchain will be analyzed.
Tokenization projects are currently very present when it comes to new blockchain technologies. After explaining the fundamentals of cross-chain interaction, the bachelor thesis will focus on tokenizing technology for Bitcoin on Ethereum. To get a more practical context, implementing the currently most successful decentralized tokenization project is described.
This paper looks at current projects in the field of Blockchain in education, their specific areas of application, possible advantages and weaknesses. Three examples developed by the team of authors are introduced in detail. First: Gallery-Defender a Serious Game, which was adapted to serve as a demonstrator in a stand-alone version to show the possibility to carry out exams directly from within the game and store the grades and meta-data on Blockchain. Second: Art-Quiz, an e-learning tool, which can be integrated into existing LMS systems and map exam results and further data using Blockchain technologies. Both were developed following an iterative design process. And third: The results of a focus group, which simulated the assignment of grades after an oral online exam. The three examples presented here are based on the Blockchain system Ardor/Childchain Ignis, but each demonstrator has a different set of features and approaches.
In addition, the integration of various Blockchain solutions was conceptually designed to make a Multi-Chain model possible.
With the increasing usage of blockchain technology, legal challenges such as GDPR compliance arise. Especially the right of erasure is considered challenging as blockchains are tamperproof by design. Several approaches investigated
possibilities to weaken the tamperproof aspect of blockchains in favor of GDPR compliance. This paper presents several approaches, then focuses on chameleon hash functions by evaluating the possibility to use these specific functions in a private blockchain. The goal of the built system is to take a step towards the digitization of the bill of lading used in international trade. This paper describes the developed software as well as the core considerations around the system such as network design or block structure.
After creating a new blockchain transaction, the next step usually is to make miners aware of it by having it propagated through the blockchain’s peer-to-peer network. We study an unintended alternative to peer-to-peer propagation: Exclusive mining. Exclusive mining is a type of collusion between a transaction initiator and a single miner (or mining pool). The initiator sends transactions through a private channel directly to the miner instead of propagating them through the peerto-peer network. Other blockchain users only become aware of these transactions once they have been included in a block by the miner. We identify three possible motivations for engaging in exclusive mining: (i) reducing transaction cost volatility (“confirmation as a service”), (ii) hiding unconfirmed transactions from the network to prevent frontrunning and (iii) camouflaging wealth transfers as transaction costs to evade taxes or launder money. We further outline why exclusive mining is difficult to prevent and introduce metrics which can be used to identify mining pools engaging in exclusive mining activity.
The set of transactions that occurs on the public ledger of an Ethereum network in a specific time frame can be represented as a directed graph, with vertices representing addresses and an edge indicating the interaction between two addresses.
While there exists preliminary research on analyzing an Ethereum network by the means of graph analysis, most existing work is focused on either the public Ethereum Mainnet or on analyzing the different semantic transaction layers using
static graph analysis in order to carve out the different network properties (such as interconnectivity, degrees of centrality, etc.) needed to characterize a blockchain network. By analyzing the consortium-run bloxberg Proof-of-Authority (PoA) Ethereum network, we show that we can identify suspicious and potentially malicious behaviour of network participants by employing statistical graph analysis. We thereby show that it is possible to identify the potentially malicious
exploitation of an unmetered and weakly secured blockchain network resource. In addition, we show that Temporal Network Analysis is a promising technique to identify the occurrence of anomalies in a PoA Ethereum network.
Mathematics Behind the Zcash
(2020)
Among all the new developed cryptocurrencies from Bitcoin, Zcash comes out to be the strongest cryptocurrency providing both transparency and anonymity to the transactions and its users by deploying the strong mathematics of zk-SNARKs.
We discussed the zero knowledge proofs which is a basic building block for providing the functionality to zk-SNARKs. It offers schnorr and sigma protocols with interactive and noninteractive versions. Non-interactive proofs are further used in Zcash transactions where the validation of sent transaction is proved by cryptographic proof.
Further, we deploy zk-SNARKs proofs following common reference string as public parameter when transaction is made. The proof allows sender to prove that she knows a secret for an instance such that the proof is succinct, can be verified very efficiently and does not leak the
secret. Non-malleability, small proofs and very effective verification make zk-SNARKs a classic tool in Zcash. Since we deal with NP problems therefore we have considered the elliptic curve cryptography to provide the same security like RSA but with smaller parameter size.
Lastly, we explain Zcash transaction process after minting the coin, the corresponding transaction completely hides the sender, receiver and amount of transaction using zero knowledge proof.
As future considerations, we talk about the improvements that can be done in term of decentralization, efficiency by comparing with top ranked cryptocurrencies namely Ethereum and Monero, privacy preserving against the thread of quantum computers and enhancements in shielded transactions.
Decentralizing Smart Energy Markets - tamper-proof-documentation of flexibility market processes
(2020)
The evolving granularity and structural decentralization of the energy system leads to a need for new tools for the efficient operation of electricity grids. Local Flexibility Markets (or "Smart Markets") provide platform concepts for market based congestion management. In this context there is a distinct need for a secure, reliable and tamper-resistant market design which requires transparent and independent monitoring of platform operation. Within the following paper different concepts for blockchain-based documentation of relevant processes on the proposed market platform are described. On this basis potential technical realizations are discussed. Finally, the implementation of one setup using Merkle tree operations is presented by using open source libraries.
Procurement processes are deemed to lack supporting digital technologies that raise efficiency and automation.
Blockchain solutions are piloted in procurement in order to offer a decentralized IT infrastructure covering these needs. This paper aims at identifying current blockchain approaches in the field of procurement and presenting affected business processes. In order to get an overview of the current state of the art, a systematic literature mapping is conducted.
Moreover, the out-comes are gathered and categorized in a classification scheme. Based on the analysis, systematic maps are presented to showcase relevant findings. Within the findings, several blockchain use cases in the field of procurement are identified and information about addressed challenges, utilized blockchain frameworks and affected business processes are extracted.