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Proof-of-work system

Proof-of-work system

A proof-of-work (POW) system (or protocol, or function) is an economic measure to deter DOS attacks and other abuses (e.g. spam) on a network by requiring some work from the service requester, usually meaning processing time.

A proof-of-work system is designed as a deterrent to spamming or denial of service attacks by requiring the expenditure of typically computational processing power. This computational work represents an economic cost which an attacker would have to waste in order to disrupt the network. A core aspect of any proof-of-work system is that it is difficult to produce an output (proving work was done sacrificing some sort of economic value) and is easy for others to verify the work was completed without performing the work again themselves.

Usage in blockchain

The Bitcoin blockchain uses a proof-of-work system derived from hashcash created by Adam Back. For a node to propose a block onto the blockchain, it must find a nonce (an arbitrary number that can only be used once) that prepends to the block and results in a hash within a small range. Bitcoin blockchain adjust the size of this range such that every block created globally has about 10 minutes interval.

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Proof of Stake versus Proof of Work

BitFury Group

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