Chainlink VRF Helps Ensure Fair Randomness for OpenSwap’s Bridge Troll NFTs

OpenSwap DEX
4 min readJan 4, 2022
  • OpenSwap chooses Chainlink VRF (Verifiable Random Function) as RNG
  • Chainlink VRF helps ensure fair randomness for generating of OpenSwap’s Bridge Troll NFTs
  • Bridge Troll NFT holders can earn bridge fees upon release of single-asset cross-chain bridges

We are elated to announce that OpenSwap — an innovative, on-chain, zero slippage DEX aggregator on Binance Smart Chain (BSC) — has integrated Chainlink Verifiable Randomness Function (VRF) to help power our NFT-powered transaction validator program.

Through an integration with the industry-leading decentralized oracle network, our Bridge Troll NFTs will now have access to a tamper-proof and auditable source of randomness needed to help ensure our community-focused reward distribution system is verifiably unbiased. Ultimately, this will help nurture additional excitement and give OpenSwap users a fraud-proof experience wherein Bridge Troll NFT holders can interact with Troll Camp and the OpenSwap Interchain Protocol in a fair and transparent manner.

How does OpenSwap use Chainlink VRF?

OpenSwap has created a series of magical NFTs that draw their power from the Binance Smart Chain. The Bridge Troll series empowers users to stake native $OSWAP tokens to collect and upgrade Bridge Troll NFTs to increase their rarity and go up in tiers through the Troll Camp portal. The capacity of the perks entitled to each NFT is different based on their tiers, and ultimately users can battle-harden and increase their Bridge Troll NFT’s value by serving as a node validator (bridge troll) for Open Interchain Protocol, a cross-chain bridging offering that provides single-asset bridge vault technology.

To ensure the generation of Bridge Troll NFTs are fair, transparent, and provably random, we need access to a secure random number generator (RNG) which community members can independently audit. However, RNG solutions for smart contracts require multiple security considerations to ensure system integrity and also to prevent potential manipulation. For example, RNG solutions based on on-chain data such as block hashes can potentially be exploited by miners via reorg attacks, and RNG solutions based on off-chain data providers are not exactly transparent and cannot provide definitive proof for process integrity.

After careful consideration, the OpenSwap team decided to go with Chainlink VRF because it is supported by Chainlink’s time-tested oracle infrastructure and secured through the generation and on-chain verification of cryptographic proofs that help ensure the integrity of each random number supplied to smart contracts.

Chainlink VRF works by combining block data that would be unknown at the time of the request made with the oracle node’s pre-committed private key to create a random number as well as cryptographic proof. The OpenSwap Troll Camp smart contract will only accept the random number input if it has valid cryptographic proof, and the cryptographic proof will only be created if the VRF process is tamper-proof. Through the adoption of Chainlink VRF, OpenSwap Troll Camp participants are provided with automated and publicly verifiable assurances on-chain that each Bridge Troll NFT generated using Chainlink VRF is truly random.

“OpenSwap’s Bridge Troll NFTs allow DeFi users to serve as node validators and earn bridge fees upon the release of our single asset cross-chain bridge — Open Interchain Protocol. NFTs with real DeFi utility are hard to come by these days, and our Chainlink VRF integration helps protect the integrity and fairness of this community-focused offering by OpenSwap.”

- Bruce Chau, CEO of OpenSwap

About Chainlink

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 or read the documentation at To discuss an integration, reach out to an expert.

About OpenSwap

OpenSwap is the world’s first DEX providing on-chain swaps at zero slippage and multi-chain arbitrage opportunities. As the DeFi universe continues to expand, liquidity becomes increasingly scattered across multiple chains and the situation is poised to get worse as new chains emerge with individual DEXs on each chain. The OpenSwap team has been working for the past several months on building up a vision of a comprehensive one-stop DeFi hub that offers the best on-chain pricing, multi-chain arbitrage, and zero slippage, allowing users to experience revolutionary benefits through optimizing their trades through unique features such as Liquidity Queues, Hybrid Smart Router, and Open Interchain Protocol.

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OpenSwap DEX

Integrated DeFi Hub designed for the decentralized landscape. Currently on Binance Smart Chain.