1 of 1

Setup an instance

First, you need to create an instance. An instance allows you to:

Encrypt inputs with blockchain public key
Manage user keys to reencrypt contract's encrypted data

createInstance

Parameters

params (required):
- chainId (required): Id of the chain
- publicKey (required): Public key of the blockchain
- keypairs (optional): A list of keypairs associated with contract

Returns

Promise<FhevmInstance>

Example

import { createInstance } from "fhevmjs";

const keypairs = {
  "0x1c786b8ca49D932AFaDCEc00827352B503edf16c": {
    publicKey: "7b2352b10cb4e379fc89094c445acb8b2161ec23a3694c309e01e797ab2bae22",
    privateKey: "764d194c6c686164fa5eb3c53ef3f7f5b90985723f19e865baf0961dd28991eb",
    signature:
      "0x5668c087804bd8b2f95b17d7f60599502bf7d539b0b19a4d989c3a5e422c77de37771be1f991223088e968a7e18330c7ece973f527eec03b97f219447d4833401b",
  },
};

const initInstance = async () => {
  // 1. Get chain id
  const chainIdHex = await window.ethereum.request({ method: "eth_chainId" });
  const chainId = parseInt(chainIdHex, 16);

  // Get blockchain public key
  const ret = await provider.call({
    // fhe lib address, may need to be changed depending on network
    to: "0x000000000000000000000000000000000000005d",
    // first four bytes of keccak256('fhePubKey(bytes1)') + 1 byte for library
    data: "0xd9d47bb001",
  });
  const decoded = ethers.AbiCoder.defaultAbiCoder().decode(["bytes"], ret);
  const publicKey = decoded[0];

  // Create instance
  return createInstance({ chainId, publicKey, keypairs });
};

initInstance().then((instance) => {
  console.log(instance.serializeKeypairs());
});