Private (permissioned) Blockchains
The opposite of a permissionless blockchain:
- the entities (Nodes) who can add blocks are known and “allowed” by the rest of the network.
- They can come in two broad categories, firstly where participants are a group of entities such as an industry blockchain, secondly as an internal blockchain, where the block adders are all under the control of one organisation.
- Private blockchains are a class of distributed ledgers that use transactions and blocks, first described in Bitcoin. Distributed ledgers are shared databases with access protection rights, with defined rules on what types of changes can be performed by what entities.
- The following information comes from this post by Consensys (5-9-2019):
"Blockchains began as open source, public efforts. Private blockchains were developed as corporations and other administrative bodies began to realize the benefits of distributed ledger technology, particularly within systems of a private enterprise and when managing sensitive transaction data. With increasingly robust and modular privacy and permissioning solutions, industry experts anticipate that private and public blockchain networks will converge."