pyth-network_pyth-crosschain/target_chains/ethereum/entropy_sdk/solidity/README.md

Pyth Entropy Solidity SDK

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.

Install

TODO

Setup

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 | 0x368397bDc956b4F23847bE244f350Bde4615F25E | optimism-goerli | 0x28F16Af4D87523910b843a801454AEde5F9B0459 | 0x368397bDc956b4F23847bE244f350Bde4615F25E | eos-evm-testnet | 0xD42c7a708E74AD19401D907a14146F006c851Ee3 | 0x368397bDc956b4F23847bE244f350Bde4615F25E

Choose one of these networks and instantiate an IEntropy contract in your solidity contract:

 IEntropy entropy = IEntropy(<address>);

Usage

To generate a random number, follow these steps.

1. Commit to a random number

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);

2. Request a number from Entropy

Invoke the request method of the IEntropy contract:

uint64 sequenceNumber = entropy.request(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.

3. Fetch the provider's number

Fetch the provider's random number from them. For the provider 0x368397bDc956b4F23847bE244f350Bde4615F25E 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.

4. Reveal the 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.