CityDAO Integrates Chainlink VRF to Support Raffle of NFT Land Plots to Citizens
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December 15th, 2021

We are excited to announce that CityDAO has integrated Chainlink Verifiable Random Function (VRF) on Ethereum mainnet. By integrating the industry-leading decentralized oracle network, we now have access to a verifiable source of on-chain randomness that is both independently auditable and completely tamper-proof. Ultimately, this gives our Citizens a way to verify that our 950 NFT land plots are raffled in a provably random manner.   

CityDAO is a decentralized autonomous organization (DAO) that is pioneering collective real-world land ownership. Currently, we are preparing to tokenize the first plot of land on-chain—a 40-acre parcel in Wyoming, USA known as Parcel 0. Due to the physical size of Parcel 0, we are minting 950 NFT plots. However, in the past few weeks we have grown to over 10,000 Citizens (governing DAO members), meaning that not every Citizen can receive a land plot.

In order to randomly select winners during the NFT plot raffle, we needed access to a secure random number generator (RNG) that any user could independently audit in order to honor our ethos of fairness, transparency, and commitment to decentralization. However, RNG solutions for smart contracts require several security considerations to prevent manipulation and ensure system integrity. For instance, RNG solutions derived from blockchain data like block hashes can be exploited by miners/validators, while off-chain RNG solutions derived from off-chain APIs are opaque and don’t provide users with definitive proof about the integrity of the process.

After reviewing various solutions, we selected Chainlink VRF. Chainlink VRF works by combining block data that is still unknown when the request is made with the oracle node's pre-committed private key to generate both a random number and a cryptographic proof. The CityDAO smart contract will only accept the random number input if it has a valid cryptographic proof, and the cryptographic proof can only be generated if the VRF process is tamper-proof. This provides our users with automated and verifiable assurances directly on-chain that the NFT raffle winners are chosen in a provably random manner.

“Chainlink VRF helps CityDAO further establish itself as a transparent, fair, and decentralized organization. With 950 land plots being raffled, Chainlink VRF gives our Citizens strong assurances that winners are chosen in a verifiably random and tamper-proof manner, and every Citizen has an equal chance of being chosen.” —the CityDAO team. 

Chainlink is the industry standard for building, accessing, and selling oracle services needed to power hybrid smart contracts on any blockchain. Chainlink oracle networks provide smart contracts with a way to reliably connect to any external API and leverage secure off-chain computations for enabling feature-rich applications. Chainlink currently secures tens of billions of dollars across DeFi, insurance, gaming, and other major industries, and offers global enterprises and leading data providers a universal gateway to all blockchains.

Learn more about Chainlink by visiting chain.link or read the documentation at docs.chain.link. To discuss an integration, reach out to an expert.

About CityDAO

CityDAO is building a network city of decentralized ownership for a community of passionate web3 builders. In doing so, we are pioneering the use of decentralized blockchain technology for physical assets to create a more efficient, fair, and opportunistic world for all.

About Parcel 0

Parcel 0 is a 40-acre piece of undeveloped land located in Park County, Wyoming. It represents a historic moment for decentralization as the first time land has been obtained by a DAO and tokenized on-chain. As CityDAO’s proof of concept, it will be offered to Citizens as 950 NFT plots.

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