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Generating Proofs

Generate proof-of-inclusion (Tezos ➡️ EVM)​

The example below calls the state aggregator contract on the Tezos blockchain, which generates a Merkle proof for a given state inserted by a given origin.

Install the SDK's:

npm install --save ibcf-sdk @taquito/taquito
import { Tezos } from "ibcf-sdk";
import { TezosToolkit } from "@taquito/taquito";

const TEZOS_RPC = "https://tezos-ghostnet-node-1.diamond.papers.tech";
const TEZOS_STATE = "KT1B8F7BhA2EeGQvPFpaVStd99ZDSzwrAcBL";

const tezosSdk = new TezosToolkit(TEZOS_RPC);
const stateAggregator = new Tezos.Contracts.StateAggregator.Contract(
  tezosSdk,
  TEZOS_STATE
);

// DApp address, the contract that inserts the state
const STATE_ORIGIN = "KT1AyXoM57cyXv8yZLn4nBNzVSmCJKMtuEdf";
// The key of the state you want to validate
const STATE_KEY = "0x01";
// Block level where the snapshot was taken
const SNAPSHOT_LEVEL = 1883726;

stateAggregator
  .getProof(
    STATE_ORIGIN, // Origin
    STATE_KEY, // State key
    SNAPSHOT_LEVEL // Block level where the snapshot was taken
  )
  .then(console.log);

Generate proof-of-inclusion (EVM ➡️ Tezos)​

The example below uses eth_getProof to extract a storage proof of an EVM smart contract.

Both the storage slot and proof are RLP encoded.

Install the SDK's:

npm install --save ibcf-sdk ethers
import { Ethereum } from "ibcf-sdk";
import { ethers } from "ethers";

const ETHEREUM_RPC = "https://goerli.infura.io/v3/75829a5785c844bc9c9e6e891130ee6f";
const ETHEREUM_DAPP = "0x715E4360a220a5e021dE5413F5c6314EDC234AC3";
const BLOCK_NUMBER = 8339150;

const provider = new ethers.providers.JsonRpcProvider(ETHEREUM_RPC);

const proofGenerator = new Ethereum.ProofGenerator(provider);

// EVM storage slot indexes (Each slot index is identified by 32 bytes)
// - storage index 0 ...
// - storage index 1 -> mapping(uint => string) action_registry;
const actionRegistryIndex = "1".padStart(64, "0");

// Key encoded as an EVM storage slot (32 bytes)
const key = "1".padStart(64, "0");

// Storage slots
// - Each mapping slot is the result of keccak256(<key> +  <slot_index>)
const actionSlot = ethers.utils.keccak256("0x" + key + actionRegistryIndex);
proofGenerator
  .generateStorageProof(ETHEREUM_DAPP, [actionSlot], BLOCK_NUMBER)
  .then(console.log);