I have a pallet which ensures a particular custom origin of H160(20 bytes). Actually, this pallet is to ensure that the Origin is that of an ethereum address(20 bytes).

I am therefore writing Integration tests using PolkadotJS, how can i send and sign a transaction by using a 20 bytes address origin?

  • When i try Bruno's suggestion, I always get: Error: createType(AccountId):: Invalid AccountId provided, expected 32 bytes, found 20
    – dharjeezy
    May 29, 2023 at 12:13

1 Answer 1


Looks like Ethereum is supported in @polkadot/keyring:

const PairFromSeed = {
  ecdsa: (seed: Uint8Array): Keypair => secp256k1FromSeed(seed),
  ed25519: (seed: Uint8Array): Keypair => ed25519FromSeed(seed),
  ethereum: (seed: Uint8Array): Keypair => secp256k1FromSeed(seed),
  sr25519: (seed: Uint8Array): Keypair => sr25519FromSeed(seed)

So you could do something like this:

// Import the keyring as required
import Keyring from '@polkadot/keyring';

// Create a keyring instance
const keyring = new Keyring({ type: 'ethereum' });

Moonbeam has excellent docs on this. As well as an example script:

import { ApiPromise, WsProvider } from '@polkadot/api';
import { Keyring } from '@polkadot/api';

const wsProvider = new WsProvider('WSS-API-ENDPOINT-HERE');
const api = await ApiPromise.create({ provider: wsProvider });

const keyring = new Keyring({ type: 'ethereum' });

const alice = keyring.addFromUri('ALICE-ACCOUNT-PRIVATE-KEY-HERE');

const tx = await api.tx.balances
  .transfer(bob, 12345n)

const encodedCallData = tx.method.toHex()

const txHash = await tx

console.log(`Submitted with hash ${txHash}`);

// Disconnect the API
  • Thanks for the response. So, I actually tried as you suggested before posting the question, but I always get this error: Error: createType(AccountId):: Invalid AccountId provided, expected 32 bytes, found 20
    – dharjeezy
    May 24, 2023 at 13:07
  • Okay. Can you open a new question with a reproducible example (actual code + repo(s)), so we can replicate the issue and solve it.
    – Bruno
    May 24, 2023 at 13:10
  • The repo is actually private, but it is similar to moonbeam's. i will open another question with code examples if that's ok
    – dharjeezy
    May 24, 2023 at 15:44

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