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Pbft Blockchain

Consensus - Blockchain

Consensus - Blockchain

New transactions are broadcast to all nodes. Each node collects new transactions into a block. Each node works on finding a difficult proof-of-work for its block. When a node finds a proof-of-work, it broadcasts the block to all nodes. Nodes accept the block only if all transactions in it are valid and not already spent. Nodes express their acceptance of the block by working on creating the next block in the chain, using the hash of the accepted block as the previous hash. Nodes always consider the longest chain to be the correct one and will keep working on extending it. Cryptocurrencies such as Bitcoin enable users to submit payment transactions without going through a centralized trusted organization. Bitcoin relies on proof-of-work mining to secure consensus which is problematic because mining requires a massive expenditure of energy, confirmation of transactions is slow, and security is difficult to quantify. There are proposals to develop new consensus algorithms, such as Proof of Stake consensus and Byzantine fault tolerance consensus. Consensus without Mining - Proof of Stake In the Proof of Stake model used by, network security is governed by peers having a stake in the network. The incentives provided by this algorithm do not promote centralization in the same way that Proof of Work algorithms do. The network has will be highly decentralized because a large number of unique accounts are contributing blocks to the network by voting, and block creation reward is shared among the participant in proportion to their stake. In a nothing at stake attack, forgers attempt to build blocks on top of every fork they see because doing so costs them almost nothing, and because ignoring any fork may mean losing out on the block rewards that would be earned if that fork were Continue reading >>

Pbft Vs Proof-of-authority: Applying The Cap Theorem To Permissioned Blockchain

Pbft Vs Proof-of-authority: Applying The Cap Theorem To Permissioned Blockchain

PBFT vs Proof-of-Authority: Applying the CAP Theorem to Permissioned Blockchain De Angelis, S.; Aniello, L.; Baldoni, R.; Lombardi, F.; Margheri, A.; Sassone, V. Permissioned blockchains are arising as a solution to federate companies prompting accountable interactions. A variety of consensus algorithms for such blockchains have been proposed, each of which has dierent benets and drawbacks. Proof-of-Authority (PoA) is a new family of Byzantine fault-tolerant (BFT) consensus algorithms largely used in practice to ensure better performance than traditional Practical Byzantine Fault Tolerance (PBFT). However, the lack of adequate analysis of PoA hinders any cautious evaluation oftheir eectiveness in real-world permissioned blockchains deployed over the Internet, hence on an eventually synchronous network experimenting Byzantine nodes. In this paper, we analyse two of the main PoA algorithms, named Aura and Clique, both in terms of provided guarantees and performances. First, we derive their functioning including how messages are exchanged, then we weight, by relying on the CAP theorem, consistency, availability and partition tolerance guarantees. We also report a qualitative latency analysis based on message rounds. The analysis advocates that PoA for per-missioned blockchains, deployed over the Internet with Byzantine nodes, do not provide adequate consistency guarantees for scenarios where data integrity is essential. We claimthat PBFT can t better such scenarios, despite a limited loss in terms of performance. Continue reading >>

How Consensus Algorithms Solve Issues With Bitcoin's Proof Of Work

How Consensus Algorithms Solve Issues With Bitcoin's Proof Of Work

How Consensus Algorithms Solve Issues with Bitcoin's Proof of Work Sep 11, 2014 at 11:12 UTC|UpdatedSep 11, 2014 at 17:18 UTC It used to be that bitcoin mining was a community affair, butthe process of confirming bitcoin transactions nowrequires an immense amount of hashing powerspecific to the SHA-256 mining algorithm. As a result, the amount of electricity required to processand verify transactions has reached animmense scale. In the early days, when the first users like the late Hal Finney began experimenting with bitcoin, users could just openthe early bitcoin client and let their CPU whir away, creating bitcoins for fractions of a penny. By contrast,mining now requires tensof thousands of dollars in equipment, electricity and optionalhostingexpenses. As a result, those who have significantfinancial resources have come to dominatethe bitcoin mining space. Mining today is embodied by the emergence ofenterprise-style, datacenter-hosted mining operations. Jackson Palmer, who created the scrypt algorithm-based, proof-of-work altcoin dogecoin , is not overly positive on the prospect of mining overall, particularly in regards to the energy consumption. "I'm quite openly against [proof of work] mining as the future of digital currencies based on the amount of energy it wastes, and damage it does to the environment - without giving anything back apart from making the fiat rich richer." One possible solution that has already been deployed in the digital currency ecosystem shifts away from proof of work, but still embodies the principles of a non-centralized systems. A major issuethat plagues mining today - but may not receive much attention - is that the application-specific integrated circuits (ASICs) for SHA-256 or scrypt mining are only capable of one process. ASICs canm Continue reading >>

Mphasis | Consensus Protocol: Why Is It Critical To Understand The Available Choices?

Mphasis | Consensus Protocol: Why Is It Critical To Understand The Available Choices?

Consensus Protocol: Why is it critical to understand the available choices? Consensus is the heart of blockchain. Consensus in the blockchain is required to guarantee very basic data store properties. The more players there are in the network, the more scalable is the network that comes with more computing power or stake. This is about building a shared data store that has enterprise data qualities that enterprise get from their network. So consensus protocol is required to guarantee security and data integrity of the architecture design. Consensus protocol plays a key role in creating a block which stores the true version of a group of transactions. The trust is built by consensus algorithms. Consensus is a state of agreement on which majority of people agree. In this article, we will discuss types of consensus protocols that are being used at time of block creation and storing transactions in enterprise level blockchain design. Consensus Protocols for Permissioned Blockchains Permissioned Blockchain network is operated by trusted nodes elected by the central authority. In a practical enterprise level blockchain application, an enterprise defines mining and signing nodes for consensus process. There are three types of Consensus protocols that are popularly used while designing permissioned blockchain architecture. The practical byzantine fault tolerance algorithm (PBFT) is used to build consensus in blockchain solutions. In PBFT consensus each leader (signing node) maintains an internal state (ongoing specific information or status). When a leader receives a message, they use the message in conjunction with their internal state to run a computation or operation. This computation, in turn, asks other leader (other nodes) if the transaction is valid. Post receiving vali Continue reading >>

Are Smart Contracts Better On A Distributed Ledger Pbft Or On A Blockchain Pow? - Quora

Are Smart Contracts Better On A Distributed Ledger Pbft Or On A Blockchain Pow? - Quora

Are smart contracts better on a Distributed Ledger PBFT or on a blockchain PoW? Are smart contracts better on a Distributed Ledger PBFT or on a blockchain PoW? PBFT and PoW are suitable for a hugely different environment. In case of PoW, when the majority of the computational power is not colluding to perform malicious acts in consensus forming, it can guarantee honest consensus without the need for courts and judges. To see why this works, lets look at the following. If we would give every client an equal vote, it would be very easy for a malicious actor to just introduce a million clients in the network to hijack the consensus forming process. This problem is solved by requiring not a lot of client, but actually a lot of computation power, so itll cost more and more resources to overtake the network. This is suitable for the public Bitcoin and Ethereum networks, where no party or jurisdiction can enforce full control on the consensus outcome. The downside of PoW is the enormous cost in energy usage, with a consequence on cost of running the network, both financially and environmentally. This is a price you have to have the desired level of security without depending on courts and judges. In the case of PBFT, another solution has been formed to prevent a malicious actor from spinning up a million clients. By identifying every individual actor that participates in consensus forming, you can ensure no single actor is participating more than once. As a result, every participant has an equal say. While this removes the enormous power requirements, it introduces another requirement: we need to agree on how to identify the parties. In the business world, this is an acceptable requirement, as countries already have registers of known businesses and the like. While this requi Continue reading >>

On Byzantine Fault Tolerance In Blockchain Systems

On Byzantine Fault Tolerance In Blockchain Systems

On Byzantine Fault Tolerance in Blockchain Systems Notable blockchain projects are investigating Byzantine Fault Tolerant (BFT) algorithms and systems, which could be increasingly important in the future due to their ability to minimize attacks and software errors which lead to faulty nodes and arbitrary behavior. It's not easy to achieve consensus in distributed systems. This problem is generally called " The Byzantine General's' problem ." Byzantine failures are common failures in software design, process, quality, and applications in software. Blockchain applications, starting with Bitcoins Proof-of-Work consensus method, are today proposing solutions to this challenge. The Byzantine Fault Tolerance (BFT) is a proposed alternative consensus algorithm to the better knownProof-of-Work and Proof-of-Stake algorithms. Notable blockchain projects like Ripple, Stellar, Hyperledger and Antshares are investigating versions of BFT systems for their blockchain-enabled products.Byzantine fault-tolerant algorithms could be increasingly important in the future due to their ability to minimize attacks and software errors which lead to faulty nodes and arbitrary behavior. Byzantine agreements work to ensure consensus despite non-rational behavior by a fraction of nodes participating in a distributed system. Generally, membership in Byzantine agreement systems is set by a central authority or closed negotiation. Notably, Ripple tried to decentralize admission in BFT systems by publishing a starter membership so participants can edit a blockchain themselves. Detractors lament that this design winds up with a concentration of power in the hands of the systems maintainer. (i.e. the organization overseeing admission membership) MIT researchers contend BFT incorporates optimizations that Continue reading >>

Pbft Vs Proof-of-authority: Applying The Cap Theorem To Permissioned Blockchain

Pbft Vs Proof-of-authority: Applying The Cap Theorem To Permissioned Blockchain

PBFT vs proof-of-authority: applying the CAP theorem to permissioned blockchain PBFT vs proof-of-authority: applying the CAP theorem to permissioned blockchain PBFT vs proof-of-authority: applying the CAP theorem to permissioned blockchain Permissioned blockchains are arising as a solution to federate companies prompting accountable interactions. A variety of consensus algorithms for such blockchains have been proposed, each of which has different benefits and drawbacks. Proof-of-Authority (PoA) is a new family of Byzantine fault-tolerant (BFT) consensus algorithms largely used in practice to ensure better performance than traditional Practical Byzantine Fault Tolerance (PBFT). However, the lack of adequate analysis of PoA hinders any cautious evaluation of their effectiveness in real-world permissioned blockchains deployed over the Internet, hence on an eventually synchronous network experimenting Byzantine nodes. In this paper, we analyse two of the main PoA algorithms, named Aura and Clique, both in terms of provided guarantees and performances. First, we derive their functioning including how messages are exchanged, then we weight, by relying on the CAP theorem, consistency, availability and partition tolerance guarantees. We also report a qualitative latency analysis based on message rounds. The analysis advocates that PoA for per- missioned blockchains, deployed over the Internet with Byzantine nodes, do not provide adequate consistency guarantees for scenarios where data integrity is essential. We claim that PBFT can fit better such scenarios, despite a limited loss in terms of performance. De Angelis, Stefano, Aniello, Leonardo, Baldoni, Roberto, Lombardi, Federico, Margheri, Andrea and Sassone, Vladimiro (2018) PBFT vs proof-of-authority: applying the CAP theo Continue reading >>

Hyperledger Fabric's Chaincode, Practical Byzantine Fault Tolerance, And V1.0 - Cloud Foundry Live | Altoros

Hyperledger Fabric's Chaincode, Practical Byzantine Fault Tolerance, And V1.0 - Cloud Foundry Live | Altoros

Think of a private blockchain as an Internet of Assets, in which you can send anything contained in a contract anywhere in the world, said , as a led a recent webinar on Hyperledger Fabric. Thomas is a blockchain developer at Optis and co-founder of TheLedger, based in the Antwerp area, Belgium. He took attendees through a fairly deep dive into Fabric v0.6the current version thats being tested by developers throughout the world. During the presentation, Thomas provided useful information in several areas: A short recap of distributed ledgers and how they compare to centralized systems Public permissionless blockchains vs. permissioned enterprise blockchains A step-by-step explanation of membership services and their responsibilities in Fabric Security, privacy, and multi-encryption in Hyperledger Fabric The chaincode structure and how it can be deployed using a CLI, Rest API, or SDK How the consensus mechanism works and what is planned for Fabric v1.0 Thomas described blockchains in general as mechanisms to draw fact-based conclusions in an auditable way, adding that consensus enhances trust. He noted advantages of the trusted, private networks that can be built with Hyperledger Fabric, in contrast to a public blockchain, such as Ethereum, in which innate anonymity of users can cause problems with accountability, and in which transaction validation takes a lot of energy. There are four types of members in a private, permissioned blockchain: Membership services provide the specific, unique certificates needed to enable members to execute their tasks. A Certificate Authority (CA) issues all certificates. There is no external registration authority yet, something that will be needed to avoid a single point of failure within the CA. Thomas also mentioned the four key aspec Continue reading >>

Cp-web/pbft-core.go At Master Ibm-blockchain-archive/cp-web Github

Cp-web/pbft-core.go At Master Ibm-blockchain-archive/cp-web Github

// custom interfaces and structure definitions // ============================================================================= // workEvent is a temporary type, to inject work // viewChangeTimerEvent is sent when the view change timer expires // execDoneEvent is sent when an execution completes // pbftMessageEvent is sent when a consensus messages is received to be sent to pbft // viewChangedEvent is sent when the view change timer expires // viewChangeResendTimerEvent is sent when the view change resend timer expires // returnRequestBatchEvent is sent by pbft when we are forwarded a request type returnRequestBatchEvent *RequestBatch // nullRequestEvent provides "keep-alive" null requests // Unless otherwise noted, all methods consume the PBFT thread, and should therefore // not rely on PBFT accomplishing any work while that thread is being held unicast(msgPayload []byte, receiverID uint64) (err error) execute(seqNo uint64, reqBatch *RequestBatch) // This is invoked on a separate thread skipTo(seqNo uint64, snapshotID []byte, peers []uint64) verify(senderID uint64, signature []byte, message []byte) error executing bool // signals that application is executing idleChan chan struct{} // Used to detect idleness for testing injectChan chan func() // Used as a hack to inject work onto the PBFT thread, to be removed eventually byzantine bool // whether this node is intentionally acting as Byzantine; useful for debugging on the testnet f int // max. number of faults we can tolerate N int // max.number of validators in the network logMultiplier uint64 // use this value to calculate log size : k*logMultiplier lastExec uint64 // last request we executed replicaCount int // number of replicas; PBFT `|R|` seqNo uint64 // PBFT "n", strictly monotonic increasing sequence number chk Continue reading >>

Consensus In Blockchain Systems. Inshort.

Consensus In Blockchain Systems. Inshort.

Scientist and Risk Taker math, informatics and their applications, in particular ML and blockchain aspiring renaissance man and polymath Consensus in Blockchain Systems. InShort. Blockchain technologies top the lists of 2017s hot trends. Many companies already back their products with blockchain technologies. Competitors use different approaches to blockchain technologies, emphasizing different aspects and pitching them as features to their customers. In this post I will provide an overview of the role of one of those particular aspects of blockchain technologies consensus. Blockchains are diverse and can be approached from a variety of perspectives. For the sake of this article, I would like to define a blockchain as a public, decentralized database, that keeps public records in an append-only fashion. Moreover, once added into the database (the blockchain) a record cannot be modified and it is very difficult to falsify entries. This last feature is called persistence. When an entry in the database (the blockchain) needs to be updated, a new record must be appended to the existing information. Finally, each of records can be viewed by any member of the public, allowing for any person to individually verify the authenticity of each transaction recorded for any single entry in the database (the blockchain). This transparency means that blockchains are auditable. CC-BY-3 Theymos from Bitcoin wiki vectorization: The main chain (black) consists of the longest series of blocks from the first (genesis) block (green) to the current block. Orphan blocks (purple) exist outside of the mainchain. But why bother with blockchains over traditional databases anyway? Blockchains become immediately appealing as soon as a database needs to be decentralized. An organization looking to av Continue reading >>

Practical Byzantine Fault Tolerance (pbft)

Practical Byzantine Fault Tolerance (pbft)

Practical Byzantine Fault Tolerance (PBFT) An algorithm that is relied upon in order to establish consensus within a blockchain system. 0 0 Jorge Vieira Jorge Vieira2018-02-02 10:09:552018-02-02 10:09:55Practical Byzantine Fault Tolerance (PBFT) Hashed Health: Healthcare Blockchain Update #24 March 26, 2018 'Mad Libs' for blockchain: Fill in the blanks now to avoid mistakes before it's too late vi yesterday RT @BlockchainNet : Great Q&A with John Bass, CEO of Hyperledger member @HashedHealth on blockchain ambitions for healthcare 2 days ago RT @TJMitch68 : It's great to see the progress of John Bass and @HashedHealth with #blockchain innovation. 2 days ago This field is for validation purposes and should be left unchanged. This iframe contains the logic required to handle Ajax powered Gravity Forms. Continue reading >>

Pros And Cons Of Different Blockchain Consensus Protocols

Pros And Cons Of Different Blockchain Consensus Protocols

Pros and Cons of Different Blockchain Consensus Protocols Blockchain consensus protocols allow a decentralized network to arrive at an agreement about the state of the blockchain. There are different ones for different types of blockchains and each has its pros and cons. Selecting and then implementing the right consensus protocol (or consensus algorithm) is a key decision to make early in your blockchain project. Consensus protocols allow the blockchain to confirm transactions without relying on a third party. And, of course, getting rid of intermediaries and decentralizing is at the heart of blockchain. Put simply, the consensus algorithm seeks to ensure that the next block to be added is, as nearly every blog and tech publication puts it, the one and only version of the truth. At the same time, its also designed to keep bad actors from tampering with or undermining the blockchain network. Consensus allows a decentralized network to arrive at an agreement about the state of the blockchain. Unless everyone participating on the blockchain is totally honest and pure of heart, consensus is essential. Consensus is the backbone of the blockchain and any other decentralized and distributed technology, writes Collin Thompson, co-founder of Intrepid Ventures. Heres a look at several blockchain consensus protocols. Well start with the best known. The correct way of thinking about the proof-of-work concept is as a means for a group of self-interested people, none of whom is subordinate to any other, to establish a consensus against a considerable incentive to resist it. Bitcoin could operate perfectly well without proof-of-work, as long as everyone was perfectly honest and altruistic. If they are not, then reaching a consensus is difficult. Satoshi Nakamoto Institute The first Continue reading >>

Blockchain Interpretation Pbft Algorithm

Blockchain Interpretation Pbft Algorithm

Practical Byzantine Fault Tolerance According to the Byzantine consensus algorithm PBFT, which evolved from the Byzantine problem, there have been various consensus algorithms since the Byzantine problem was proposed Solve the Byzantine problem, but the currently accepted PBFT is the most efficient algorithm regardless of the complexity of the implementation process or the efficiency of the algorithm. The algorithm was proposed by Miguel Castro and Barbara Liskov in 1999, which solved the inefficiency of the original Byzantine fault-tolerant algorithm and reduced the complexity of the algorithm from exponential to polynomial , Making Byzantine fault tolerance algorithm in practical application of the system becomes feasible. By map Byzantium problem. & nbsp; 3m + 1. In the system requires the entire system to have security and activity. The entire system passes the copy of the state machine features to convey information. First talk about security, in the case of n> 3m + 1, the security is the number of copies (& lt; m) allows a certain failure, the system through these failure node control changes to access the new Resume malicious attacks. Active, synchronized approach does not provide security, but provides activity, in an asynchronous system, by the same request after the failure of the copy does not exceed m, and the delay time control, then eventually this message will be at Re-send in asynchronous mode is accepted as well, ensuring system activity as well. Pure theory to understand still have a certain degree of difficulty, simple explanation through the algorithm flow: First assume that there are n nodes, m failure nodes, n> 3m + 1, there are 3m + 1 copies, The copy set is F {3m + 1}. Reality may have an extra copy of 3m + 1, but theoretically only so much, and Continue reading >>

Byzantine Fault Tolerance

Byzantine Fault Tolerance

"Byzantine generals" redirects here. For military generals of the Byzantine empire, see Category:Byzantine generals . In fault-tolerant computer systems , and in particular distributed computing systems, Byzantine fault tolerance (BFT) is the characteristic of a system that tolerates the class of failures known as the Byzantine Generals' Problem , [1] which is a generalized version of the Two Generals' Problem for which there is an unsolvability proof. The phrases interactive consistency or source congruency have been used to refer to Byzantine fault tolerance, particularly among the members of some early implementation teams. [2] It is also referred to as error avalanche, Byzantine agreement problem, Byzantine generals problem and Byzantine failure. Byzantine failures are considered the most general and most difficult class of failures among the failure modes . The so-called fail-stop failure mode occupies the simplest end of the spectrum. Whereas fail-stop failure model simply means that the only way to fail is a node crash, detected by other nodes, Byzantine failures imply no restrictions, which means that the failed node can generate arbitrary data, pretending to be a correct one. Thus, Byzantine failures can confuse failure detection systems, which makes fault tolerance difficult. A Byzantine fault is any fault presenting different symptoms to different observers. [3] A Byzantine failure is the loss of a system service due to a Byzantine fault in systems that require consensus . [4] The objective of Byzantine fault tolerance is to be able to defend against Byzantine failures, in which components of a system fail with symptoms that prevent some components of the system from reaching agreement among themselves, where such agreement is needed for the correct operatio Continue reading >>

Introduction Hyperledger-fabricdocs Master Documentation

Introduction Hyperledger-fabricdocs Master Documentation

Hyperledger Fabric is a platform for distributed ledger solutions underpinnedby a modular architecture delivering high degrees of confidentiality,resiliency, flexibility and scalability. It is designed to support pluggableimplementations of different components and accommodate the complexity andintricacies that exist across the economic ecosystem. Hyperledger Fabric delivers a uniquely elastic and extensible architecture, distinguishingit from alternative blockchain solutions. Planning for the future of enterpriseblockchain requires building on top of a fully vetted, open-source architecture;Hyperledger Fabric is your starting point. We recommend first-time users begin by going through the rest of theintroduction below in order to gain familiarity with how blockchains workand with the specific features and components of Hyperledger Fabric. Once comfortable or if youre already familiar with blockchain andHyperledger Fabric go to Getting Started and from there explore thedemos, technical specifications, APIs, etc. At the heart of a blockchain network is a distributed ledger that records allthe transactions that take place on the network. A blockchain ledger is often described as decentralized because it is replicatedacross many network participants, each of whom collaborate in its maintenance.Well see that decentralization and collaboration are powerful attributes thatmirror the way businesses exchange goods and services in the real world. In addition to being decentralized and collaborative, the information recordedto a blockchain is append-only, using cryptographic techniques that guaranteethat once a transaction has been addedto the ledger it cannot be modified. This property of immutability makes itsimple to determine the provenance of information because participant Continue reading >>

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