Jul 07, 2016
Jul 07, 2016
本白皮书介绍 Flare，一种用于闪电网络支付路由的混合路由算法。本文提出一种两阶段算法：(1) 主动更新节点的路由图，存储有关网络拓扑的信息，以及 (2) 根据闪电网络请求的需要，按需被动收集信息。这份白皮书首次尝试描述和初步测试算法解决方案，用于未来比特币区块链闪电网络的实施，这将允许交易处理的可扩展性。论文是与合著者 Olaoluwa Osuntokun 以及闪电网络团队其他成员合作的成果。
每个人都应该了解的有关区块链的 4 个事实
May 12, 2016
Mar 15, 2016
Bitfury 集团的白皮书“公共区块链中的数字资产”探讨如何在保障比特币安全的公共区块链安全地存储和转移数字资产。数字资产是由资产发行人担保的某项服务或商品的流动债权，由计算机技术和互联网管理。在撰写这份白皮书的整个过程中，Bitfury 集团发现，使用区块链架构进行数字资产管理将允许全球经济创建纯粹的数字资产，并完全在线管理这些资产。我们的白皮书得出结论，这项福利将为拥抱世界各地的机遇打开许多新的大门。
Digital asset management is one of promising applications of blockchain technology. Blockchains could provide principal disintermediation between digital asset issuers, application developers and consumers and decouple tasks related to asset management, such as issuance, transaction processing, securing users’ funds and establishing users’ identities. This paper outlines basic components of blockchain-based asset ledgers, as well as their use cases for financial services and for emerging Internet of Things and consumer-to-consumer markets. We describe existing and prospective deployment models for asset ledgers, including multi-asset blockchains, colored coin and metacoin protocols. This paper focuses primarily on Bitcoin-based services and, to a lesser degree, on public blockchains in general.
Dec 07, 2015
We estimate incentives to notarize transactions on the Bitcoin blockchain at about $5 million daily by 2020 (which is five times more than the present value) and at $50–100 million daily by 2025. By 2020, transaction fees could constitute 50% or more of the notarial incentives due to increasing velocity of Bitcoin and the increased value secured with the Bitcoin blockchain; the amount of transaction fees as a percentage of total incentives could grow to 80–90% by 2025. The growth would be achieved due to both the increase in transaction fees and the growing Bitcoin exchange rate. With the stabilization of Bitcoin markets and the increasing role of transaction fees in notarial incentives, the role of the Bitcoin exchange rate is expected to diminish.
Oct 20, 2015
We provide a description of permissioned blockchain systems that could be used in creating secure ledgers or timestamped registries. We contend that the blockchain protocol and data should be accessible to end users to provide a higher level of decentralization and transparency and argue that proof of work could be effectively used in permissioned blockchains as a decentralized and auditable means of providing and diversifying security. We describe merged mining and blockchain anchoring concepts, which would be instrumental in implementing proof of work security for permissioned blockchains.
There is currently an ongoing debate whether the existing blockchain-based systems (such as Bitcoin and other cryptocurrencies) can be utilized as is in proprietary contexts, and whether their openness and censorship resistance are fitting properties in this case. We provide arguments for the use of permissionless blockchains and open, standardized blockchain protocols in creating ledgers and registries, devoting particular attention to the Bitcoin blockchain as the most commercially successful and secure permissionless blockchain. We argue that many permissioned applications could be effectively implemented using existing technologies on top of existing permissionless blockchains:
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Mathematical formalism for the voting process in Bitcoin ecosystem
Sep 13, 2015
We propose a mathematical formalism for the voting process in Bitcoin ecosystem. This formalism can be used to algorithmically determine the best value of a certain parameter (e.g., a block size limit) which will be considered appropriate by all voters. The proposed approach is aimed to clarify vagueness of some proposed voting processes that potentially allows a party with marginal voting power to dictate their conditions to the rest of the network. To solve the problem, we introduce a non-negative dissatisfaction function and minimize its value summed over all votes. The value of the block size limit (and, potentially, other parameters of the protocol) found this way will satisfy voters provided the dissatisfaction function is chosen appropriately.
Proof of Stake vs Proof of Work
Sep 11, 2015
Proof of stake is a consensus mechanism for digital currencies that is an alternative to proof of work used in Bitcoin. The main declared advantages of proof of stake approaches are the absence of expensive computations and hence a lower entry barrier for block generation rewards. In this white paper, we examine the pros and cons of both consensus systems and show that existing implementations of proof of stake are vulnerable to attacks which are highly unlikely in Bitcoin and proof of work approaches in general.
We consider several problems and possible attack vectors arising in proof of stake cryptocurrencies:
We estimate the cost of various types of attacks on proof of stake currencies and compare it with the cost of similar attacks on a proof of work currency. The cost of attacks on proof of stake is shown to be significantly lower.
We also consider delegated, or deposit-based, proof of stake consensus as an ongoing evolution of basic proof of stake. This version of proof of stake is more resistant to attacks and could potentially be a formidable opponent to proof of work, when it is sufficiently tested in practice and gains a foothold. On the other hand, just like basic proof of stake, delegated systems require a combination of algorithmic and social-driven security; the social component of proof of stake currencies could weaken their decentralization and mathematical soundness.
Bitfury Report On Block Size Increase
Aug 31, 2015
We believe that in order for Bitcoin ecosystem to prosper, the maximum block size must be increased. It is a common understanding among Bitcoin developers that the current limit of one megabyte hinders scalability of Bitcoin Blockchain and prevents its wide adoption as the technology of the future.
We have thoroughly studied all block size increase proposals and find that Jeff Garzik's BIP 100 proposal is the most reasonable and considerate one. We think that the block size debate must be resolved by a consensus and the voting mechanism introduced in BIP 100 is a good way to achieve such a consensus. The forecasts of growth of the Bitcoin network made in other proposals don't provide enough predictive power, so in such case the cost of mistake is extremely high. The power to make such future defining decisions must belong to the community. Ultimately, it is up to all network participants to decide what number of full nodes is sufficient to preserve decentralization, not just hardware growth trends. We believe that BIP 100 is the best solution in this regard.
Please see the extended report below:
Smart Contracts on Bitcoin Blockchain
Aug 13, 2015
Smart contracts are one of the more promising directions for cryptocurrencies and Bitcoin in particular. A smart contract is understood as a computer protocol used to facilitate and automate financial contracts. The term smart contract was introduced by Nick Szabo in 1990s and became more relevant than ever before in 2010s after digital currencies gained popularity.
One of the advantages in using Bitcoin as a medium for smart contracts is the inherent low trust approach. Built-in Bitcoin mechanisms let users minimize counterparty risks by utilizing mathematical and algorithmic tools, not by relying on a mediator’s authority, as is often the case in the traditional approach.
Bitcoin is criticized because of the insufficient expressive means for smart contracts. The Ethereum project launched on July 30th, 2015 was developed as a replacement of the Bitcoin protocol specifically targeted for smart contract users. Because of the critique, the following questions arise:
what possibilities and perspectives does the Bitcoin protocol have as a medium for smart contracts?
what are the main drawbacks of Bitcoin compared to the alternatives (e.g., Ethereum)? Can these drawbacks be eliminated or alleviated while staying within the protocol?
This report studies possible smart contract applications for Bitcoin and outlines directions for further research.