The Pyth Entropy Solidity SDK allows you to generate secure random numbers on the blockchain by interacting with the Pyth Entropy protocol. This SDK can be used for any application that requires random numbers, such as NFT mints, gaming, and more.
WARNING: The Entropy protocol is currently in testnet. It is NOT INTENDED for use in production applications. Use this protocol at your own risk.
npm install @pythnetwork/entropy-sdk-solidity
To use the SDK, you need the address of an Entropy contract on your blockchain and a randomness provider. The following table lists the current deployments of entropy.
| Chain | Entropy Address | Provider |
|-----------------|--------------------------------------------|--------------------------------------------|
| avalanche-fuji | 0xD42c7a708E74AD19401D907a14146F006c851Ee3 | 0x6CC14824Ea2918f5De5C2f75A9Da968ad4BD6344 |
| optimism-goerli | 0x28F16Af4D87523910b843a801454AEde5F9B0459 | 0x6CC14824Ea2918f5De5C2f75A9Da968ad4BD6344 |
| eos-evm-testnet | 0xD42c7a708E74AD19401D907a14146F006c851Ee3 | 0x6CC14824Ea2918f5De5C2f75A9Da968ad4BD6344 |
| arbitrum-goerli | 0xd9eAcfFB8e80b7193042499485EF8369b08E85B6 | 0x6CC14824Ea2918f5De5C2f75A9Da968ad4BD6344 |
Choose one of these networks and instantiate an IEntropy contract in your solidity contract:
IEntropy entropy = IEntropy(<address>);
To generate a random number, follow these steps.
Generate a 32-byte random number on the client side, then hash it with keccak256 to create a commitment. You can do this with typescript and web3.js as follows:
const randomNumber = web3.utils.randomHex(32);
const commitment = web3.utils.keccak256(randomNumber);
Invoke the request method of the IEntropy contract.
The request method requires paying a fee in native gas tokens which is configured per-provider.
Use the getFee method to calculate the fee and send it as the value of the request call:
uint fee = entropy.getFee(provider);
uint64 sequenceNumber = entropy.request{value: fee}(provider, commitment, true);
This method returns a sequence number. Store this sequence number for use in later steps.
If you are invoking this off-chain, the method also emits a PythRandomEvents.Requested event that contains the sequence number in it.
Fetch the provider's random number from them.
For the provider 0x6CC14824Ea2918f5De5C2f75A9Da968ad4BD6344 you can query the webservice at https://fortuna-staging.pyth.network :
await axios.get(
`https://fortuna-staging.pyth.network/v1/chains/${chainName}/revelations/${sequenceNumber}`
);
This method returns a JSON object containing the provider's random number.
Invoke the reveal method on the IEntropy contract:
bytes32 randomNumber = entropy.reveal(
provider,
sequenceNumber,
randomNumber,
providerRandomNumber
)
This method will combine the user and provider's random numbers, along with the blockhash, to construct the final secure random number.
The Coin Flip example demonstrates how to build a smart contract that interacts with Pyth Entropy as well as a typescript client for that application.