Switching from Chainlink VRF to Pyth Entropy

As decentralized applications (dApps) continue to evolve, the demand for robust, transparent, and cost-effective solutions is ever-growing. In the world of prediction markets, derivative sand blockchain gaming, randomness plays a crucial role in determining outcomes that users can trust. Historically, Chainlink’s VRF (Verifiable Random Function) has been the go-to solution for generating secure random numbers on-chain. However, with the rise of innovative alternatives like Pyth Entropy, the landscape is shifting.

We’ll walk through the key differences between both services, discuss the benefits of Pyth Entropy, and provide a detailed look at the Solidity code behind the transition.

Why Randomness Matters in Blockchain Applications

Randomness ensures fairness and unpredictability in dApps, especially in use cases like gaming, lotteries, and prediction markets. Without a trusted source of randomness, dApps risk exposing themselves to manipulation or biases that could undermine user trust.

In a simple Coin Flip Game, randomness determines whether the outcome is heads or tails. Thus, ensuring the randomness source is reliable is critical to maintaining fairness

Chainlink’s VRF

The Chainlink VRF has been the industry standard for generating verifiable random numbers on-chain, it ensures that random numbers used in a smart contract are unpredictable. The randomness is generated off-chain and then verified on-chain, providing both security and transparency.
Key Features of Chainlink VRF Integration:

Subscription Model: Users need to set up and fund a Chainlink subscription.
Verifiable Randomness: Random numbers are generated and verified by the Chainlink network.
Gas Costs: Chainlink VRF involves higher gas fees due to off-chain processing and interaction with the Chainlink oracle network.
Sample Chainlink VRF Solidity Code for Coin Flip.

function playWithVRF(bool face) external payable {
        Bet memory bet = _playWithVRF();
        coinTossBets[bet.id].face = face;

        emit PlaceBet(bet.id, bet.user, face);
    }

    function _playWithVRF() internal returns (Bet memory) {
        uint256 requestId = s_vrfCoordinator.requestRandomWords(
            VRFV2PlusClient.RandomWordsRequest({
                keyHash: keyHash,
                subId: s_subscriptionId,
                requestConfirmations: requestConfirmations,
                callbackGasLimit: callbackGasLimit,
                numWords: numWords,
                // native payment = false, means chainlink will charge user $LINK tokens (cheaper method)
                // native payment = true, means chainlink will charge ETH 
                extraArgs: VRFV2PlusClient._argsToBytes(
                    VRFV2PlusClient.ExtraArgsV1({nativePayment: false})
                )
            })
        );

        Bet memory newBet = Bet(
            false,
            msg.sender,
            requestId,
            block.timestamp,
            false
        );
        _userBets[msg.sender].push(requestId);
        bets[requestId] = newBet;
        return newBet;
    }

    function fulfillRandomWords(
        uint256 _requestId /* requestId */,
        uint256[] calldata randomWords
    ) internal override {
        CoinTossBet storage coinTossBet = coinTossBets[_requestId];
        Bet storage bet = bets[_requestId];
        uint256 roller = randomWords[0] % 2;

        bool[2] memory coinSides = [false, true];
        bool rolledCoinSide = coinSides[roller];
        coinTossBet.rolled = rolledCoinSide;

        if (rolledCoinSide == coinTossBet.face) {
            bet.resolved = true;
            bet.betStatus = true;
            emit Roll(bet.id, bet.user, coinTossBet.face, rolledCoinSide);
        } else {
            bet.resolved = true;
            bet.betStatus = false;
            emit Roll(bet.id, bet.user, coinTossBet.face, rolledCoinSide);
        }

        emit Roll(bet.id, bet.user, coinTossBet.face, rolledCoinSide);
    }

    function getBetData(uint256 id) public view returns (Bet memory betData) {
        Bet storage data = bets[id];
        return data;
    }

Enter Pyth Entropy: A New Standard for On-Chain Randomness

While Chainlink VRF provides an excellent solution, Pyth Entropy presents several advantages for dApps , particularly in terms of gas efficiency, flexibility, and integration with the existing Pyth Network ecosystem. Pyth Entropy is a randomness generator that ensures decentralized and verifiable randomness on-chain, just like VRF, but offers a more streamlined and cost-efficient model.

*Why Switch to Pyth Entropy?
*

Lower Fees: Pyth Entropy requires fewer resources than Chainlink VRF, leading to lower transaction costs for users.
Direct Integration with Pyth Network: dApps which already uses Pyth for its price feeds, making the integration of Entropy a natural fit.
Scalability: As a dApp expands its product offerings, using a more scalable solution like Pyth Entropy ensures that future random-based features can be easily integrated.
Faster Response Times: Since Pyth Entropy processes directly on-chain, the randomness is returned faster than with off-chain processes.

*Sample Pyth Entropy Solidity Code for Coin Flip:
*

function getProvider() external view returns (address) {
        address p = entropy.getDefaultProvider();
        return p;
    }

    function getFlipFee() public view returns (uint256 fee) {
        fee = entropy.getFee(entropyProvider);
    }

    function entropyCallback(
        uint64 sequenceNumber,
        address,
        bytes32 randomNumber
    ) internal override {
        uint256 _s = uint256(sequenceNumber);
        CoinTossBet storage coinTossBet = coinTossBets[_s];
        Bet storage bet = bets[_s];
        bool rolled = uint256(randomNumber) % 2 == 0;

        coinTossBet.rolled = rolled;

        if (rolled == coinTossBet.face) {
            bet.resolved = true;
            bet.betStatus = true;
            emit Roll(bet.id, bet.user, coinTossBet.face, rolled);
        } else {
            bet.resolved = true;
            bet.betStatus = false;

            emit Roll(bet.id, bet.user, coinTossBet.face, rolled);
        }

        emit Roll(bet.id, bet.user, coinTossBet.face, rolled);
        emit FlipResult(sequenceNumber, uint256(randomNumber) % 2 == 0);
    }

    function getEntropy() internal view override returns (address) {
        return address(entropy);
    }

    function flipWithPyth(
        bool face,
        bytes32 userRandomNumber
    ) external payable {
        address provider = entropy.getDefaultProvider();
        uint256 fee = entropy.getFee(provider);

        if (msg.value < fee) {
            revert CoinFlipErrors.InsufficientFee();
        }

        uint64 sequenceNumber = entropy.requestWithCallback{value: fee}(
            provider,
            userRandomNumber
        );

        uint256 _s = uint256(sequenceNumber);
        emit FlipRequest(sequenceNumber);
        Bet memory newBet = Bet(false, msg.sender, _s, block.timestamp, false);
        _userBets[msg.sender].push(_s);
        bets[_s] = newBet;

        coinTossBets[newBet.id].face = face;

        emit PlaceBet(newBet.id, newBet.user, face);
    }

*The decision to transition from Chainlink VRF to Pyth *

Entropy is more than just a technical upgrade for any dApp. It’s a step toward a more scalable, cost-effective future that aligns with the platform’s goals of transparency and user-centric design.
As Pyth Entropy continues to grow in adoption, we expect to see more projects making the switch, particularly those already embedded in the Pyth ecosystem.
The decision to transition from Chainlink VRF to Pyth Entropy is more than just a technical upgrade for any dApp. It’s a step toward a more scalable, cost-effective future that aligns with the platform’s goals of transparency and user-centric design.
As Pyth Entropy continues to grow in adoption, we expect to see more projects making the switch, particularly those already embedded in the Pyth ecosystem.

To get access to the full Solidity code and hardhat environment use 👇
Repo Link

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Pyth
https://docs.pyth.network/entropy — docs

Chainlink
https://vrf.chain.link/ — subscription manager
https://docs.chain.link/vrf — docs

Blog

Switching from Chainlink VRF to Pyth Entropy

Mr Wonder

Why Randomness Matters in Blockchain Applications

Chainlink’s VRF

Enter Pyth Entropy: A New Standard for On-Chain Randomness

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