This article is about the protocol. For other uses, see Ouroboros (disambiguation).
The ouroboros, Kekulé's inspiration for the structure of benzene. It is used to symbolize the ever-growing consensus on the Cardano blockchain
Ouroboros is a family of proof-of-stake consensus protocols used in the Cardano blockchain. It can run both permissionless and permissioned blockchains.[1]
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.[2] Later that year, Ouroboros (Classic) was used by IOHK as the basis of the Cardano blockchain platform and various upgrades.[3][4][5] Ouroboros versions include:[6]
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; [7][non-primary source needed]
Ouroboros Praos (2017)[8] 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): security with a dynamic participation model;
Ouroboros Chronos (2019): protocol is independent of global time;[9]
Ouroboros Crypsinous (2019) gives higher levels of privacy.
Cardano's founder Charles Hoskinson has described the Ouroboros consensus mechanism as energy efficient.[4] Nguyen et al. compared Ouroboros to other PoS protocols.[10]
^Kiayias, Aggelos; Russell, Alexander; David, Bernardo; Oliynykov, Roman (27 July 2017). "Ouroboros: A Provably Secure Proof-of-Stake Blockchain Protocol". In Katz, J.; Shacham, H. (eds.). Advances in Cryptology – Crypto 2017. Cham: Springer. pp. 357–388. doi:10.1007/978-3-319-63688-7_12. ISBN 978-3-319-63688-7.