Chainlink VRF v1 Deprecated for On-Chain Randomness
Developers using Chainlink for verifiable randomness are being directed to migrate from the deprecated VRF v1 to v2.5. The newer version, which became the standard in late 2024, is essential for smart contracts in gaming and prediction markets, offering improved security and more flexible funding models. VRF v2.5 is now supported across multiple blockchains.
- The initial version of Chainlink VRF was launched on the Ethereum mainnet on October 22, 2020, with early adopters like PoolTogether using it to randomly select prize winners. - A significant architectural shift from v1 to v2.5 is the introduction of a subscription management model. This allows up to 100 smart contract addresses to pre-fund their randomness requests from a single balance, reducing gas fees by eliminating the need to transfer LINK tokens for each individual request. - For developers in the prediction market and gaming sectors, VRF v2.5's direct funding option simplifies passing on transaction costs to the end-user. This is because the cost is calculated at the time of the request, rather than during the fulfillment callback. - In November 2023, Chainlink awarded a $300,000 bounty to white-hat hackers who discovered a critical vulnerability. A malicious subscription owner could have blocked and rerolled randomness requests until they achieved a desired outcome; Chainlink has since implemented a fix to prevent this. - The deprecation of both v1 and v2 is scheduled for November 29, 2024, by which time all users are expected to have migrated to v2.5. - A key security consideration with any on-chain randomness solution, including all versions of Chainlink VRF, is the risk of blockchain reorganizations ("reorgs"). A miner or validator could theoretically rewrite a chain's history to place a randomness request in a different block, resulting in a different random output. - VRF v2.5 introduces a more predictable pricing model where the premium is a percentage of the gas costs for the VRF callback, rather than a flat LINK fee. This model helps ensure dApps receive timely responses even during periods of high network congestion.
