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Blockchain

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Network block formation
Cipher-block chaining operations
Bitcoin network data

A blockchain[1][2][3] — originally block chain[4][5] — is a distributed database that maintains a continuously-growing list of ordered records called blocks.[1] Each block contains a timestamp and a link to a previous block.[6]: 6  The data in a block cannot be altered retrospectively. Blockchains are secure by design and an example of a distributed computing system with high byzantine fault tolerance.

By design blockchains are inherently resistant to modification of the data. Decentralised consensus can therefore be achieved for the first time with a blockchain.[7] This makes blockchains suitable for the recording of events and other records management activities, identity management, transaction processing and proving provenance. This offers the potential of mass disintermediation and vast repercussions for how global trade is conducted.

The first blockchain was conceptualised by Satoshi Nakamoto in 2008 and implemented the following year as a core component of the digital currency bitcoin, where it serves as the public ledger for all transactions.[1] Through the use of a peer-to-peer network and a distributed timestamping server a blockchain database is managed autonomously. The invention of the blockchain for bitcoin made it the first digital currency to solve the double spending problem. The bitcoin design has been the inspiration for other applications.[1][3]

History

Bitcoin transactions (January 2009 - September 2015)

First work on cryptographically secured chain of blocks was described in 1991 by Stuart Haber and W. Scott Stornetta. Followed by publications in 1996 by Ross J. Anderson and 1998 by Bruce Schneier and John Kelsey.[8] In parallel there was work going on in 1998 by Nick Szabo working on a mechanism for a decentralized digital currency that he called bit gold.[9] In 2000 Stefan Konst published a general theory for cryptographic secured chains and suggested a set of solutions for implementation.[8]

The first blockchain was then conceptualised by Satoshi Nakamoto in 2008 and implemented the following year as a core component of the digital currency bitcoin, where it serves as the public ledger for all transactions.[1] Through the use of a peer-to-peer network and a distributed timestamping server a blockchain database is managed autonomously. The invention of the blockchain for bitcoin made it the first digital currency to solve the double spending problem. The bitcoin design has been the inspiration for other applications.[1][3]

The blockchain format was first used for bitcoin, as a solution to the problem of making a database both secure and not requiring a trusted administrator.[4] The words block and chain were used separately in Satoshi Nakamoto's original paper in October 2008,[10] and when the term moved into wider use it was originally block chain,[4][5] before becoming a single word, blockchain, by 2016. In August 2014, the bitcoin blockchain file size reached 20 gigabytes in size.[11]

As of 2014, "Blockchain 2.0" was a term referring to new applications of the distributed blockchain database.[12] The Economist described one implementation of this second-generation programmable blockchain as coming with "a programming language that allows users to write more sophisticated smart contracts, thus creating invoices that pay themselves when a shipment arrives or share certificates which automatically send their owners dividends if profits reach a certain level."[1]

In 2016, the central securities depository of the Russian Federation (NSD) announced a pilot project based on blockchain technology.[13] Various regulatory bodies in the music industry have started testing models that use blockchain technology for royalty collection and management of copyrights around the world.[14][better source needed] IBM opened a blockchain innovation research centre in Singapore in July 2016.[15] A working group for the World Economic Forum met in November 2016 to discuss the development of governance models related to blockchain.[16] According to Accenture an application of the diffusion of innovations theory suggests that in 2016 blockchains attained a 13.5% adoption rate within financial services, therefore reaching the early adopters phase.[17]

Description

External videos
video icon A visual demonstration of the six key components in a blockchain

Blockchain is a secured way of online transaction.[18] A blockchain is a decentralized digital ledger that records transactions on thousands of computers globally in such a way that the registered transactions cannot be altered retrospectively.[19][1] They are authenticated by mass collaboration powered by collective self-interests.[20] The result is a robust workflow where participants' uncertainty regarding data security is marginal. The use of a blockchain removes the characteristic of infinite reproducibility from a digital asset. It confirms that each unit of digital cash was spent only once, solving the long-standing problem of double spending. Blockchains have been described as a value-exchange protocol.[12] This exchange of value can be completed more quickly, safely and cheaper with a blockchain.[21] A blockchain can assign title rights because it provides a record that compels offer and acceptance.[1]

A blockchain database consists of two kinds of records: transactions and blocks.[1] Blocks hold batches of valid transactions that are hashed and encoded into a Merkle tree.[1] Each block includes the hash of the prior block in the blockchain, linking the two. The linked blocks form a chain.[1] This iterative process confirms the integrity of the previous block, all the way back to the original genesis block.[22] Variants of this format were used previously, for example in Git, and it is not by itself sufficient to qualify as a blockchain.[23]

Sometimes separate blocks can be validated concurrently, creating a temporary fork. In addition to a secure hash based history, any blockchain has a specified algorithm for scoring different versions of the history so that one with a higher value can be selected over others. Blocks which are not selected for inclusion in the chain are called orphan blocks.[22] Peers supporting the database don't have exactly the same version of the history at all times, rather they keep the highest scoring version of the database that they currently know of. Whenever a peer receives a higher scoring version (usually the old version with a single new block added) they extend or overwrite their own database and retransmit the improvement to their peers. There is never an absolute guarantee that any particular entry will remain in the best version of the history forever, but because blockchains are typically built to add the score of new blocks onto old blocks and there are incentives to only work on extending with new blocks rather than overwriting old blocks, the probability of an entry becoming superseded goes down exponentially,[24] as more blocks are built on top of it, eventually becoming very low.[1][25]: ch. 08 [26] For example, in a blockchain using the proof-of-work system, the chain with the most cumulative proof-of-work is always considered the valid one by the network. In practice there are a number of methods that can demonstrate a sufficient level of computation. Within a blockchain the computation is carried out redundantly rather than in the traditional segregated and parallel manner.[27]

The blockchain is parsed by software to extract relevant information.[28] The Nxt cryptocurrency community considered and dismissed a blockchain rollback in 2014 after a theft at a major exchange.[29]

Decentralization

Blockchain secure workflow
Step Activity
1 Digitally signed transaction initiation
2 Transaction is sent to miner who verifies transaction
3 Transaction is broadcast to all connected nodes as block
4 Network accepts transaction if data is valid
5 Receiver receives the transaction
Source: iFour Technolab[18]

By storing data across its network, the blockchain eliminates the risks that come with data being held centrally.[1] Its network lacks centralized points of vulnerability that computer hackers can exploit or any central point of failure. Blockchain security methods include the use of public-key cryptography.[4]: 5  A public key (a long, randomly-generated string of numbers) is an address on the blockchain. Bitcoins sent across the network are recorded as belonging to that address. A private key is like a password that gives its owner access to their digital assets or otherwise interact with the various capabilities that blockchains now support. Data stored on the blockchain is generally considered incorruptible.[1]

Every node or miner in a decentralized system has a copy of the blockchain. Data quality is maintained by massive database replication[7] and computational trust. No centralized "official" copy exists and no user is "trusted" more than any other.[4] Transactions are broadcast to the network using software. Messages are delivered on a best effort basis. Mining nodes validate transactions,[22] add them to the block they’re creating, and then broadcast the completed block to other nodes.[25]: ch. 08  Blockchains use various time-stamping schemes, such as proof-of-work to serialize changes.[30] Alternate consensus methods include proof-of-stake and proof of burn.[22]

Openness

Blockchain data

Since all early blockchains were permissionless, controversy has arisen over whether permissioned databases of chained blocks of data should even be considered blockchains. An issue in this ongoing debate is whether a private system with verifiers tasked and authorized (permissioned) by a central authority should be considered a blockchain.[31][32][33][34][35]

Proponents of permissioned or private chains argue that the term "blockchain" may be applied to any data structure that batches data into time-stamped blocks. These blockchains serve as a distributed version of multiversion concurrency control (MVCC) in databases.[36] Just as MVCC prevents two transactions from concurrently modifying a single object in a database, blockchains prevent two transactions from spending the same single output in a blockchain.[37]: 30–31 

Opponents say that permissioned systems resemble traditional corporate databases, not supporting decentralized data verification, and that such systems are not hardened against operator tampering and revision.[31][33] The Harvard Business Review defines blockchain as a distributed ledger or database open to anyone,[38] and Computerworld claims that "much of [blockchain hype] is nothing more than snake oil and spin".[39]

Permissionless

The great advantage to an open, permissionless network is that guarding against bad actors is not required and no access control is needed.[24] Gatekeeping is not possible.[citation needed] This means that applications can be added to the edge of the network without the approval or trust of others, using the blockchain as a transport layer.[24] This openness allows researchers to examine real-time transaction data in a closed economic system.

Bitcoin and Ethereum currently secure their blockchain by requiring new entries including a proof of work. To prolong the blockchain, bitcoin uses Hashcash puzzles developed by Adam Back in the 1990s.[40] Ethereum plans to switch to a proof-of-stake system in the future.[41]

Market capitalization

Bitcoin and Ethereum use open (public) blockchains. As of September 2016, bitcoin has the highest market capitalization while Ethereum is second.[42]

Permissioned

Permissioned blockchains have the ability to restrict who can participate in the consensus processes as well as who can transact.[27] These private blockchains lack transparency. They do not rely on anonymous miners to validate transactions nor do they benefit from the network effect.[43] Miners are vetted. The New York Times notes that many corporations are using blockchain networks "with private blockchains, independent of the public system."[3]

Disadvantages

Nikolai Hampton pointed out in Computerworld that

  • "There is also no need for a ‘51 percent’ attack on a private blockchain, as the private blockchain (most likely) already controls 100 percent of all block creation resources. If you could attack or damage the blockchain creation tools on a private corporate server, you could effectively control 100 percent of their network and alter transactions however you wished."[39] This has a set of particularly profound adverse implications during a financial crises or debt crises like the financial crisis of 2007–08, where politically powerful actors may make decisions that favor some groups at the expense of others.[citation needed]
  • "The bitcoin blockchain is protected by the massive group mining effort. It's unlikely that any private blockchain will try to protect records using gigawatts of computing power — it's time consuming and expensive."[39]
  • "Within a private blockchain there is also no ‘race’; there's no incentive to use more power or discover blocks faster than competitors. This means that many in-house blockchain solutions will be nothing more than cumbersome databases."[39]

Applications

The use of blockchains promises to be able to bring significant efficiencies to global supply chains although many observers remain skeptical. Some analysts, such as Steve Wilson from Constellation Research believe the technology has been hyped with unrealistic claims.[44] In order to mitigate risk businesses are reluctant to place blockchain at the core of the business structure.[45] Blockchains are a technology that may be integrated into multiple areas. It is a disruptive innovation because it allows businesses to use to new methods of processing digital transactions.[46] Examples include a payment system and digital currency, facilitating crowdsales, or implementing prediction markets and generic governance tools.[citation needed] Blockchains are expected to disrupt the cloud computing industry although practical technical issues remain as obstacles.[47]

Major applications of blockchain include cryptocurrencies—including bitcoin, BlackCoin, Dash, and Nxt—and blockchain platforms—Factom as a distributed registry, Gems for decentralized messaging, MaidSafe for decentralized applications, Storj for a distributed cloud, and Tezos for decentralized voting.[37]: 94  Frameworks and trials such as the one at the Sweden Land Registry aim to demonstrate the effectiveness of the blockchain at speeding land sale deals.[48] The Republic of Georgia is piloting a blockchain-based property registry.[49]The Ethical and Fair Creators Association uses blockchain to help startups protect their authentic ideas.[50]

New distribution methods for the insurance industry such as peer-to-peer insurance, parametric insurance and microinsurance following the adoption of blockchain.[46] Banks are interested in this technology because it has potential to speed up back office settlement systems.[51] The sharing economy and IoT are also set to benefit from blockchains because they involve many collaborating peers.[52]

Smart contracts

Blockchain-based smart contracts are currently in development. One of the main objectives of a smart contract is automated escrow. The IMF believes blockchains could reduce moral hazards and optimize the use of contracts in general.[53] Due to the lack of widespread use their legal status is unclear.[53]

Some blockchain implementations could enable the coding of contracts that will execute when specified conditions are met. A blockchain smart contract would be enabled by extensible programming instructions which both define and execute an agreement.[54] For example, Ethereum is an open source blockchain project that was built specifically to realize this possibility by implementing a Turing-complete programming language capability to implement such contracts.[37]: ch. 11  As of January 2016, smart contract systems are not being used for ether.[55]

Applications

The Harvard Business Review conducted a two-year research project exploring how blockchain technology can securely move and store host "money, titles, deeds, music, art, scientific discoveries, intellectual property, and even votes".[38] Furthermore, major portions of the financial industry are implementing distributed ledgers for use in banking[56][57], and according to a September 2016 IBM study, this is occurring faster than expected.[58] The credit and debits payments company MasterCard has added three blockchain-based APIs for programmers to use in developing both P2P and B2B payment systems.[59]

CLS Group is using blockchain technology to expand the number of currency trade deals it can settle.[45]

Alternative blockchains

Alternative blockchains, known as altchains, are based on bitcoin technology in concept and/or code.[6] These designs generally add functionality to the blockchain design. Altchains can provide solutions including other digital currencies, although tokens used in these designs are not always considered to be such. Altchains target performance, anonymity, storage and applications such as smart contracts.[60] Starting with a strong focus on financial applications, blockchain technology is extending to activities including decentralized applications and collaborative organizations that eliminate a middleman.[61][non-primary source needed] Notable designs include:

Other uses

Blockchain technology can be used to create a permanent, public, transparent ledger system for compiling data on sales, storing rights data by authenticating copyright registration,[65] and tracking digital use and payments to content creators, such as musicians.[66] Imogen Heap's Mycelia[67] service allowing managers to use a blockchain for tracking high-value parts moving through a supply chain was launched as a concept in July 2016. Everledger, "building systems to record the movement of diamonds from mines to jewelry stores", is one of the inaugural clients of IBM's blockchain-based tracking service.[68]

Commercial offerings

Distributed ledgers and other blockchain inspired software are being developed by commercial organizations for various applications:

In August 2016 a research team at the University of Munich published a research document about how blockchains may disrupt industries. They analyzed the venture funding that went into blockchain ventures. Their research shows that $1.55 Billion went into startups with an industry focus on finance and insurance, information and communication, and professional services. High startup density was found in the USA, UK and Canada.[74]

See also

References

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Further reading

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