What is the Difference Between Public and Permissioned Blockchains?

In our guide "How Does Blockchain Technology Work?", we introduced a description of the three technologies that make up blockchain technology: cryptographic keys, a distributed network and a network servicing protocol.

Bitcoin is the most ambitious kind of blockchain. Anyone can use bitcoin's cryptographic keys, anyone can be a node and join the network, and anyone can become a miner to service the network and seek a reward. Miners can walk away from being a node, return if and when they feel like it, and get a full account of all network activity since they left.

Basically, anyone can read the chain, anyone can make legitimate changes and anyone can write a new block into the chain (as long as they follow the rules). Bitcoin is totally decentralized. It is also described as a 'censor-proof' blockchain.

For these reasons, it's known by its widest description, a public blockchain. But, this is not the only way to build a blockchain.

Blockchains can be built that require permission to read the information on the blockchain, that limit the parties who can transact on the blockchain and that set who can serve the network by writing new blocks into the chain.

For example, Ripple runs a permissioned blockchain. The startup determines who may act as transaction validator on their network, and it has included CGI, MIT and Microsoft as transaction validators, while also building its own nodes in different locations around the world.

A blockchain developer may choose to make the system of record available for everyone to read, but they may not wish to allow anyone to be a node, serving the network's security, transaction verification or mining. It's a mix-and-match situation that is reflected in the various ways entrepreneurs are experimenting with the technology.

With permissioned blockchains, this may or may not involve 'proof of work' or some other system requirement from the nodes. There is some politics around this, as there are those who consider private blockchains that do not use any proof of work (that is, blockchains with no mining) to not be blockchains at all, but simply shared ledgers.

Authored by Nolan Bauerle; Coindesk
NEXT: WHAT IS THE DIFFERENCE BETWEEN A BLOCKCHAIN AND A DATABASE?

INDEX: A BEGINNERS GUIDE TO BITCOIN AND BLOCKCHAIN TECHNOLOGY



What is Bitcoin?
It’s a decentralized digital currency


Why Use Bitcoin?
It’s fast, cheap to use, and secure


How Can I Buy Bitcoin?
From an exchange or an individual


How to Buy Bitcoin in the UK
Buying bitcoin in the UK


How to Store Your Bitcoin
Use a digital or paper wallet


What Can You Buy with Bitcoin?
Spend your bitcoins


How to Sell Bitcoin
A guide on how to sell your bitcoins


How to Accept Bitcoin Payments for Your Store
Learn about bitcoin POS systems


How do Bitcoin Transactions Work?
Bitcoin addresses and private keys


Is Bitcoin Legal?
The current regulation around bitcoin


Who is Satoshi Nakamoto?
The founder of bitcoin


How Bitcoin Mining Works
By confirming transactions


How to Set Up a Bitcoin Miner
Generate bitcoins yourself


What are Bitcoin Mining Pools?
What are pools how and how to join them?


How Does Cloud Mining Bitcoin Work?
Alternative bitcoin mining solutions


How to Calculate Mining Profitability
Can you make a ROI?


How to Make a Paper Bitcoin Wallet
Creating an unhackable bitcoin wallet


Can Bitcoin Scale?
A look at the debate and the tech


What is SegWit?
A new way of storing transaction data


What is the Lightning Network?
Off-chain transaction channels


What is Bitcoin Cash?
Same blockchain, different characteristics.


Hard Fork vs Soft Fork
Why and how do blockchains split?


What is the Difference Between Litecoin and Bitcoin?
It’s the silver to bitcoin’s gold


How to Buy Litecoin
How to buy the bitcoin alternative litecoin


How to Mine Litecoin and other Altcoins
How to generate your own altcoins


Understanding Bitcoin Price Charts
A primer on bitcoin price charts


Bitcoin E-Commerce Services for Merchants
How to accept bitcoin at your business


What is Blockchain Technology?
A system of distributed data and logic


How Does Blockchain Technology Work?
Cryptographic keys, distributed networks and network servicing protocols


What Can a Blockchain Do?
Identity, recordkeeping, smart contracts and more


What is a Distributed Ledger?
A dynamic, independently maintained database


What is the Difference Between Public and Permissioned Blockchains?
Can anyone read or write to the ledger?


What is the Difference Between a Blockchain and a Database?
It begins with architectural and administrative decisions


What Are the Applications and Use Cases of Blockchains?
Tokenization, auditing, governance, settlement and more


How Could Blockchain Technology Change Finance?
Cross-border payments, new asset classes, regulatory compliance and more


What are Blockchain’s Issues and Limitations?
Complexity, size, costs, speed, security, politics and more


Why Use a Blockchain?
To manage and secure digital relationships as part of a system of record


What is Ethereum?
A blockchain application platform and ‘world computer’


What is Ether?
The ‘fuel’ of the ethereum network


How to Use Ethereum
Wallets, trading and ‘dapps’


Who Created Ethereum?
Vitalik Buterin


How Ethereum Mining Works
‘Proof of Work’ and ‘Proof of Stake’


How to Mine Ethereum
GPUs, mining software and pools


How Ethereum Works
‘Turing-complete’ programming, ‘state’ and the ‘EVM’


What is a Decentralized Application?
A distributed ‘smart contract’ system


What is a DAO?
A ‘decentralized autonomous organization’


How Do Ethereum Smart Contracts Work?
Code, transaction fees and ‘gas’


How Will Ethereum Scale?
‘Sharding’ and ‘off-chain’ transactions


What is an ICO?
Initial Coin Offerings refer to the distribution of digital tokens.

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