Ouroboros (protocol)

Ouroboros is a family of proof-of-stake consensus protocols used in the Cardano and Polkadot blockchains. It can run both permissionless and permissioned blockchains.

Ouroboros was published as "the first provable secure PoS consensus protocol". It was postulated by an academic team led by Aggelos Kiayias at the Annual International Cryptology Conference in 2017. Later that year, Ouroboros (Classic) was implemented by IOHK as the basis of the Cardano blockchain platform and various upgrades. Ouroboros versions include:

* Ouroboros BFT was an interim version used in 2020 to enable the switch between the Classic and Praos versions of Cardano using a hard fork combinator that preserved the blockchain history;
* Ouroboros Praos (2017) provided security against fully-adaptive corruption in the semi-synchronous model. In 2020, this version was used to introduce decentralized block production on Cardano by stake pools;
* Ouroboros Genesis (2018) provides security with a dynamic participation model;
* Ouroboros Chronos (2019) is independent of global time;
* Ouroboros Crypsinous (2019) gives higher levels of privacy.

Cardano's founder Charles Hoskinson has described the Ouroboros consensus mechanism as energy efficient. Nguyen et al. compared Ouroboros to other PoS protocols. The cryptocurrency Polkadot uses an adapted form of Ouroboros called Blind Assignment for Blockchain Extension.
Kiayias home page at University of Edinburgh

References

External links

Ouroboros
at Cardano Foundation

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Digital currencies