Abstract: Cryptocurrencies, based on and led by Bitcoin, have shown promise as infrastructure for pseudonymous online payments, cheap remittance, trustless digital asset exchange, and smart contracts. However, Bitcoin-derived blockchain protocols have inherent scalability limits that trade-off between throughput and latency and withhold the realization of this potential. This paper presents Bitcoin-NG, a new blockchain protocol designed to scale. Based on Bitcoin's blockchain protocol, Bitcoin-NG is Byzantine fault tolerant, is robust to extreme churn, and shares the same trust model obviating qualitative changes to the ecosystem. In addition to Bitcoin-NG, we introduce several novel metrics of interest in quantifying the security and efficiency of Bitcoin-like blockchain protocols. We implement Bitcoin-NG and perform large-scale experiments at 15% the size of the operational Bitcoin system, using unchanged clients of both protocols. These experiments demonstrate that Bitcoin-NG scales optimally, with bandwidth limited only by the capacity of the individual nodes and latency limited only by the propagation time of the network.

Abstract: In this chapter we provide an overview of the concept of blockchain technology and its potential to disrupt the world of banking through facilitating global money remittance, smart contracts, automated banking ledgers and digital assets. In this regard, we first provide a brief overview of the core aspects of this technology, as well as the second-generation contract-based developments. From there we discuss key issues that must be considered in developing such ledger based technologies in a banking context.

Abstract: This paper presents the first generalized reputation system that can be applied to multiple networks that is based on the blockchain. We first discuss current reputation systems, conducting a critical analysis of their current security vulnerabilities, before looking at how new blockchain based technologies are used. We propose an innovative new reputation system that is based on blockchain technologies which aims to solve many unanswered questions in today's current generation reputation systems. We then consider the limitations of such a system, before using simulations and analyses to demonstrate methods of overcoming these limitations. We conclude by suggesting areas for future studies, and summarizing our findings.

Abstract: Reports on the concept of blockchains, a new form of information technology that could have several important future applications. One is blockchain thinking, formulating thinking as a blockchain process. This could have benefits for both artificial intelligence and human enhancement, and their potential integration. Blockchain thinking is outlined here as an input-processing-output computational system.

Abstract: A proposal is made to use blockchain technology for recording contracts. A new protocol using the technology is described that makes it possible to confirm that contractor consent has been obtained and to archive the contractual document in the blockchain.

Abstract: A system, method, and computer readable storage medium configured for storing encrypted data in a blockchain. To write additional data in a blockchain, a request is received at a computing node. The request is typically cryptographically signed by a user system to include a new transaction with additional data in the blockchain. The additional data is previously encrypted with an encryption key. A new block that records the new transaction with additional data in the blockchain is added. To read the additional data in a blockchain, a request is received at a computing node with a transaction identifier and a decryption key from a user system to access data journaled as part of the blockchain in the transaction database. The transaction database is searched using the identifier. In response, to finding the corresponding block in the blockchain, the data is decrypted using the decryption key.

Abstract: We propose a concept for a new rights management system based on the blockchain technology, which is famous for supporting the reliability of the bitcoin. We clarify problems that occur when we apply the blockchain technology to the rights management system, and we also describe our trial implementation.

Abstract: Emerging smart contract systems over decentralized cryptocurrencies allow mutually distrustful parties to transact safely without trusted third parties. In the event of contractual breaches or aborts, the decentralized blockchain ensures that honest parties obtain commensurate compensation. Existing systems, however, lack transactional privacy. All transactions, including flow of money between pseudonyms and amount transacted, are exposed on the blockchain. We present Hawk, a decentralized smart contract system that does not store financial transactions in the clear on the blockchain, thus retaining transactional privacy from the public’s view. A Hawk programmer can write a private smart contract in an intuitive manner without having to implement cryptography, and our compiler automatically generates an efficient cryptographic protocol where contractual parties interact with the blockchain, using cryptographic primitives such as zero-knowledge proofs. To formally define and reason about the security of our protocols, we are the first to formalize the blockchain model of cryptography. The formal modeling is of independent interest. We advocate the community to adopt such a formal model when designing applications atop decentralized blockchains.

Abstract: A method for validating electronic transactions using a private blockchain includes: storing a blockchain, wherein the blockchain is a distributed database that includes a plurality of data records, each being associated with a processed transaction; receiving a transaction message, the transaction message including a message type indicator and a plurality of data elements, each configured to store a transaction data value; generating a data record, the data record including the message type indicator and one or more transaction data values; updating the blockchain to include the generated data record; electronically transmitting the received transaction message to a payment network for processing; and electronically transmitting the updated blockchain to a plurality of transaction processing devices for validation.

Abstract: The disclosed embodiments include computerized systems and methods for generating secured blockchain-based ledger data structures that track an ownership and usage of one or more assets, such as Internet-connected devices. In one instance, an apparatus associated with a rules authority of the secured blockchain-based ledger may detect an occurrence of a triggering event, and may access and decrypt a set of rules hashed into the secured blockchain-based ledger using a confidentially-held master cryptographic key. The apparatus may identify a rule associated with the detected event, and perform one or more operations consistent with the rule, including a determination of metrics indicative of a care, risk, and/or valuation of one or more of the Internet-connected devices, and additionally or alternatively, a modification of an operational or communicative functionality of the Internet-connected devices.

Abstract: A computer implemented method for detecting malicious events occurring with respect to a blockchain data structure comprising: defining a transaction creation profile according to which transactions can be generated and submitted to the blockchain; submitting a transaction to the blockchain, the transaction causing the generation of a profiler data structure in the blockchain including executable code to generate profile transactions to be submitted to the blockchain according to the transaction creation profile; monitoring the blockchain to identify profile transactions; and comparing identified profile transactions with the transaction creation profile to detect a deviation from the transaction creation profile, such detection corresponding to a malicious event occurring with respect to the blockchain.

Abstract: Sidecoin is a mechanism that allows a snapshot to be taken of Bitcoin's blockchain. We compile a list of Bitcoin's unspent transaction outputs, then use these outputs and their corresponding balances to bootstrap a new blockchain. This allows the preservation of Bitcoin's economic state in the context of a new blockchain, which may provide new features and technical innovations.

Abstract: We give an interpretation of full classical linear logic, and linear proofs in terms of operations on the blockchain.

Abstract: Just as decentralization communication systems lead to the creation of the Internet, today a new technology — the blockchain — has the potential to decentralize the way we store data and manage information, potentially leading to a reduced role for one of the most important regulatory actors in our society: the middleman. Blockchain technology enables the creation of decentralized currencies, self-executing digital contracts (smart contracts) and intelligent assets that can be controlled over the Internet (smart property). The blockchain also enables the development of new governance systems with more democratic or participatory decision-making, and decentralized (autonomous) organizations that can operate over a network of computers without any human intervention. These applications have lead many to compare the blockchain to the Internet, with accompanying predictions that this technology will shift the balance of power away from centralized authorities in the field of communications, business, and even politics or law.In this Article, we explore the benefits and drawbacks of this emerging decentralized technology and argue that its widespread deployment will lead to expansion of a new subset of law, which we term Lex Cryptographia: rules administered through self-executing smart contracts and decentralized (autonomous) organizations. As blockchain technology becomes widely adopted, centralized authorities, such as governmental agencies and large multinational corporations, could lose the ability to control and shape the activities of disparate people through existing means. As a result, there will be an increasing need to focus on how to regulate blockchain technology and how to shape the creation and deployment of these emerging decentralized organizations in ways that have yet to be explored under current legal theory.

Abstract: Blockchain is a distributed database that maintains a dynamic list of data records, hardened to prevent tampering and revision. It is the framework for cryptocurrencies like Bitcoin. A Blockchain learning tool would provide a secure and verifiable learning transaction ledger. Its decentralised nature would ensure a learner, rather than institution-centred record of achievements that would be difficult to tamper with, enabling parties, such as employers or learning institutions, to review with confidence. As a mechanism for transferring credit, Blockchain might also be used to enable selected actions to be rewarded with tokens that can be then traded against future learning costs. We will describe Blockchain Learning and invite colleagues to form a community to investigate its learning and teaching potential further.

Abstract: Blockchain, an innovative public ledger of transactions that underpins digital currencies such as Bitcoin, has the potential to open up and offer radical alternatives to civic life, democracy and society. Yet there is currently only a small, technically savvy section of society who understand its principles. Therefore in order to work through and realize the potential of the blockchain and its transferability across society we need to find means to open up and reduce its 'ineffable' nature. This paper presents and reflects on an approach that made the complexity of the blockchain understandable or 'effable' using physical modeling. The design-based approach adopted a tangible system of Lego and colored stickers to allow participant-actors to physically enact transactions on a Blockchain Lego 'block'. This modeled simplification was not designed as a comprehensive or accurate explanation of Bitcoin and Blockchain but rather as a prompt for opening up rich dialogue and insightful lines of questioning.

Abstract: The blockchain-based digital content distribution system was developed. Decentralized and pear-to-pear authentication mechanism can be considered as the ideal rights management mechanism. The blockchain has the potential to realize this ideal content distribution system. This is the successful model of the Superdistribution concept which was announced almost 30 years ago. The proposed system was demonstrated and got a lot of feedback for the future practical system.