Proof of Work Rule - Find a Small Hash Value
This section describes the Proof of Work Rule - Finds a nonce that result a small SHA256 hash value.
The third important Bitcoin Consensus Rule is the Proof of Work Rule:
The block hash must meet the cryptographic difficulty requirement.
As of 2018, the block hash must be less than or equal to
Details of the Proof of Work Rule are described below:
- The cryptographic difficulty requirement is defined as
the block hash must be less than or equal to the current hash target value.
- The hash target value started with
- The current hash target value is mapped to a floating-point value called
- The highest difficulty, "Difficulty = 1.0", is mapped to "Hash target =
- The current difficulty is readjusted every 2016 blocks based on
block generation times of the past 2016 blocks.
The average block generation time is longer that 10 minutes, the difficulty will be decreased.
The average block generation time is shorter that 10 minutes, the difficulty will be increased.
As you can see, the main objective of the proof of work rule
is to ensure that it will take about 10 minutes to generate, or mine, a new block
consistently over time.
As of now, the current Bitcoin difficulty is 3007383866429.732,
which can be mapped roughly to a hash target of
See the Bitcoin
Difficulty Wiki article, on how to convert difficulty to hash target.
Last update: 2018.
Table of Contents
About This Book
Introduction of Bitcoin
Bitcoin-Qt - Bitcoin Core GUI
►Bitcoin Consensus Rules
What Are Bitcoin Consensus Rules
Controlled Supply Rule - Total of 21M BTC
Mining Reward Rule - Start with 50 BTC
►Proof of Work Rule - Find a Small Hash Value
Bitcoin Block Data Structure
Bitcoin Transaction Data Structure
Copay - Bitcoin Wallet
PDF Printing Version