pseudorandom sequence) and to produce one new output thereof every round by using threshold signatures and distributed key generation. Algorand uses VRFs to perform cryptographic sortition. In this platform, every block produces a new random selection seed, and a user secretly checks whether they were selected to participate in the consensus protocol by evaluating a VRF with their secret participation key and the selection seed. (This also produces a proof, which the user can send to anyone to show that they have been selected to participate.) Thusly, accounts are selected to propose blocks for a given round. In this manner, VRFs prevent users from gaining staking advantages by registering multiple accounts. The particular VRF that Algorand uses is based on elliptic-curve cryptography, specifically Curve25519; proposed by Sharon Goldberg, Moni Naor, Dimitris Papadopoulos, Leonid Reyzin, and Jan Včelák, the function is currently undergoing standardization as an IETF Internet Draft. Algorand's own implementation of this function has been open-source since October 2018. VRFs based on elliptic curve cryptography have been implemented in the programming language Solidity. In May 2020, Chainlink announced that it launched Chainlink VRF, a service that uses verifiable random functions to generate verifiable randomness on-chain. To use Chainlink VRF, a smart contract supplies a seed (which should be unpredictable to the oracles to whom it is provided), and the seed in turn is used to generate a random number that is sent back to the contract; this is published on-chain along with a proof and verified using the oracle's public key and the application's seed. Each oracle, when generating randomness, uses its own secret key. In July 2021, Harmony, a cryptocurrency project that bridges between blockchains, and Oraichain, a cryptocurrency project involving artificial intelligence, announced that they had introduced VRFs. In February 2022, Switchboard, a decentralized oracle protocol, announced the very first verifiable random function (VRF) on the Solana blockchain. The Switchboard VRF is inspired and modelled after Algorand's VRF. References Cryptographic algorithms Cryptographic primitives Pseudorandomness