permissionless blockchain [English]
No definition in earlier IP projects. ITrust definition not yet developed.
- Blockchain Technologies 2016 (†789 s.v. "Unpermissioned ledgers"): Unpermissioned ledgers such as Bitcoin have no single owner — indeed, they cannot be owned. The purpose of an unpermissioned ledger is to allow anyone to contribute data to the ledger and for everyone in possession of the ledger to have identical copies. This creates censorship resistance, which means that no actor can prevent a transaction from being added to the ledger. Participants maintain the integrity of the ledger by reaching a consensus about its state.
- Brakeville and Perepa 2017 (†813 ): A blockchain network can be either permissioned or permissionless. Permissionless networks are open to any participant, and transactions are verified against the pre-existing rules of the network. Any participant can view transactions on the ledger, even if participants are anonymous. Bitcoin is the most familiar example of a permissionless network.
- ISO TC307 N38 (United States). 2017. (†834 s.v. "Permissions options"): Permissionless networks are open to any participant, and transactions are verified against the pre-existing rules of the network. Any participant can view transactions on the ledger, even if participants are anonymous. Bitcoin is the most familiar example of a permissionless network.
- ISO TC307 N67 (United Kingdom). 2017. (†841 p.2; s.v. "permissionless network"): blockchain network where nodes and users are essentially anonymous and where any user can use the network without authentication or authorization.
- Buterin  (†818 s.v. "History"): In 2009, a decentralized currency was for the first time implemented in practice by Satoshi Nakamoto, combining established primitives for managing ownership through public key cryptography with a consensus algorithm for keeping track of who owns coins, known as "proof of work." · The mechanism behind proof of work was a breakthrough because it simultaneously solved two problems. First, it provided a simple and moderately effective consensus algorithm, allowing nodes in the network to collectively agree on a set of updates to the state of the Bitcoin ledger. Second, it provided a mechanism for allowing free entry into the consensus process, solving the political problem of deciding who gets to influence the consensus, while simultaneously preventing Sybil attacks. (†2115)
- Buterin  (†818 s.v. "History"): Since then, an alternative approach has been proposed called proof of stake, calculating the weight of a node as being proportional to its currency holdings and not its computational resources. (†2116)
- ISO TC307 N38 (United States). 2017. (†834 s.v. "High-level View of a Blockchain Network): In a permissionless blockchain, any person can perform transactions, but they are usually restricted from performing operations on any data but their own. (†2191)
- Popper 2016 (†814 ): Blockchains are designed to store transactions and data without requiring any central authority or repository. Blockchain ledgers are generally maintained and updated by networks of computers working together — somewhat similar to the way that Wikipedia is updated and maintained by all its users. (†2090)
- Walport 2016 (†802 p.35): businesses often find ‘permissioned’ block chains far more appealing than Bitcoin’s unpermissioned model, because specific parties are authorised to verify transactions. (†2128)