How to bind an Ethereum H160 address with a Substrate H256 address?

Question

I'm trying to bind a H160 address with a H256 address, if we assume this function:

fn bind(origin: OriginFor<T>, address: H160 , signature: [u8; 130]) -> Result<(), Error<T>>{
    // check the signature belonging to an address
    ensure!(check_signature(address, signature), Error<T>);

    // bind the sender with the address
    create_account(sender, address);

    Ok(())
}

Is this function available in Substrate? Or do you have any advice on how to do the bind function?

Answer 1

H160 has a few flavors that you might pursue in the context of a Substrate chain:

• If you are looking to map H160 Ethereum addresses to, say, SR25519 that is most common in Substrate chains, it is good to see the implementation in Frontier as a reference. Here a truncated hash scheme is used (H256 -> H160 by taking the first 160 (LE) bytes in the address). There are some tools to inspect truncated vs. Ethereum converted (ECDSA <-> SR25519) addresses in the frontier node template.

• Another important example is to use H160 addresses as the base for accounting in you chain, this is exemplified in Moonbeam's Unified Accounts

Answer 2

because this PR was merged, Frontier now also supports Moonbeam's Unified Accounts (aka AccountId20)

Answer 3

I have one regular accountid32 on one parachain and I want to convert the address to a moonbeam/evm/accountid20 address, is this a proper implementation to convert accountid32 > accountid20?

import { addressToEvm } from "@polkadot/util-crypto";
import { decodeAddress, encodeAddress } from '@polkadot/keyring';
import { Keyring } from '@polkadot/keyring';


function get_test_account() {

    const e0 = new Keyring({ type: 'sr25519' });
    const account = e0.addFromUri('seed here');

    return account;
}

export const u8aToHex = (bytes: number[] | Uint8Array): string => {
  const arr = bytes instanceof Uint8Array ? Array.from(bytes) : bytes
  return '0x' + arr.reduce((str, byte) => str + byte.toString(16).padStart(2, '0'), '');
}

async function main(){
      const sender = get_test_account(); // load ss58 regular account
       console.log(`Substrate address:`, sender.address);
       const byteArray = addressToEvm(sender.address); // take the accountid32 address and convert it to a evm address uint8 array
       console.log(`Raw Evm address:`, byteArray);

  console.log(`evm address:`, u8aToHex(byteArray)); // convert the u8 to hex to display the address 

}