README

micro-eth-signer

Create, sign and validate Ethereum transactions & addresses with minimum deps.

Library's size is <500 lines of code, or 3KiB gzipped (8.7KiB minified). Uses three dependencies (SHA-3, RLP & secp256k1), four libraries combined are 13KiB gzipped (37KiB minified).

Validated with over 3MiB of ethers.js test vectors!

Usage

npm install micro-eth-signer

Supports Node.js & all major browsers. If you're looking for a fully-contained single-file version, check out Releases page on GitHub.

const { Address, Transaction } = require('micro-eth-signer');

(async () => {
  const tx = new Transaction({
    to: '0xdf90dea0e0bf5ca6d2a7f0cb86874ba6714f463e',
    maxFeePerGas: 100n * 10n ** 9n, // 100 gwei in wei
    value: 10n ** 18n, // 1 eth in wei
    nonce: 1
  });
  const privateKey = '6b911fd37cdf5c81d4c0adb1ab7fa822ed253ab0ad9aa18d77257c88b29b718e';
  const signedTx = await tx.sign(privateKey); // Uint8Array is also accepted
  const {hash, hex} = signedTx;

  // Strings can be used also
  // tx = new Transaction({"nonce": "0x01"})
  // Same goes to serialized representation
  // tx = new Transaction('0xeb018502540be40082520894df90dea0e0bf5ca6d2a7f0cb86874ba6714f463e872386f26fc1000080808080');

  // Various tx properties
  console.log('Need wei', tx.upfrontCost); // also, tx.fee, tx.amount, tx.sender, etc

  // Address manipulation
  const addr = Address.fromPrivateKey(privateKey);
  const pubKey = signedTx.recoverSenderPublicKey();
  console.log('Verified', Address.verifyChecksum(addr));
  console.log('addr is correct', signedTx.sender, signedTx.sender == addr);
  console.log(signedTx);

  // London style txs, EIP 1559
  const legacyTx = new Transaction({
    to: '0xdf90dea0e0bf5ca6d2a7f0cb86874ba6714f463e',
    gasPrice: 100n * 10n ** 9n, // 100 gwei in wei
    value: 10n ** 18n, // 1 eth in wei
    nonce: 1
  }, undefined, undefined, 'legacy');

  const berlinTx = new Transaction({
    to: '0xdf90dea0e0bf5ca6d2a7f0cb86874ba6714f463e',
    maxFeePerGas: 100n * 10n ** 9n, // 100 gwei in wei
    maxPriorityFeePerGas: 1n * 10n ** 9n, // 1 gwei in wei
    value: 10n ** 18n, // 1 eth in wei
    nonce: 1,
    // the field can also be used in eip1559 txs
    accessList: [{
      "address": "0x123456789a123456789a123456789a123456789a",
      "storageKeys": [
        "0x0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
      ]
    }]
  }, undefined, undefined, 'eip2930');
})();

API

Address

Represents ETH address and has following methods:

Address.fromPrivateKey(privateKey: string | Uint8Array): string - create address from private key
Address.fromPublicKey(publicKey: string | Uint8Array): string - creates address from public key
Address.checksum(nonChecksummedAddress: string): string - creates checksummed address from non-checksummed address
Address.verifyChecksum(address: string): boolean - verifies checksummed & non-checksummed address

Usage:

const addr = "0x0089d53f703f7e0843953d48133f74ce247184c2";
const addrc = Address.checksum(addr) // 0x0089d53F703f7E0843953D48133f74cE247184c2
Address.verifyChecksum(addrc) // true
Address.verifyChecksum(addr) // true also (non-checksummed)
Address.fromPrivateKey("0687640ee33ef844baba3329db9e16130bd1735cbae3657bd64aed25e9a5c377")
  // 0xD4fE407789e11a27b7888A324eC597435353dC35
Address.fromPublicKey("030fba7ba5cfbf8b00dd6f3024153fc44ddda93727da58c99326eb0edd08195cdb")
  // 0xD4fE407789e11a27b7888A324eC597435353dC35

Transaction

Represents unsigned & signed ETH transactions. They are serialized & deserialized using RLP. Here's an example of the same transaction in raw state, and serialized state:

// raw
{
  "nonce": "0x01", "gasLimit": "0x5208", "gasPrice": "0x02540be400",
  "to": "0xdf90dea0e0bf5ca6d2a7f0cb86874ba6714f463e",
  "value": "2386f26fc10000", "data": "0x"
}
// serialized
"0xeb018502540be40082520894df90dea0e0bf5ca6d2a7f0cb86874ba6714f463e872386f26fc1000080808080"

You can use either of those to initialize new Transaction. There are a few methods available:

new Transaction(serialized[, chain, hardfork, type]) - creates transaction from Raw TX string.
- chain: optional argument (default is mainnet; ropsten, rinkeby, goerli, kovan etc)
- hardfork: optional argument (default is london). The only place we're checking for hardfork is the replay protection code. There are very old transactions that don't support replay protection, you'll probably won't need them
- type: optional argument (default is eip1559). Can be either legacy, eip2930, or eip1559 (Berlin and London style transactions with access lists and maxFeePerGas/maxPriorityFeePerGas)
new Transaction(rawTx[, chain, hardfork, type]) - creates transaction from Raw TX data.
- rawTx must have fields to, value, nonce, gasLimit
- rawTx must have maxFeePerGas (eip1559 txs) or gasPrice (berlin & legacy txs)
- to is recipient's address
- value is amount to send in wei
- nonce is sender's nonce in number
- gasLimit is transaction's Gas Limit in wei (minimum is 21000)
- maxFeePerGas is eip1559 transaction's max acceptable gas price in wei (100 gwei is 100 * 10 ** 9). Not applicable to legacy transactions
- maxPriorityFeePerGas is eip1559 transaction's max acceptable tip in wei. Not applicable to legacy transactions
- gasPrice is legacy transaction's Gas Price in wei. Not applicable to eip1559 transactions
- data is transaction's data if it's calling some smart contracts
- accessList is transaction's Access List, a list of addresses that its smart contract call touches. Basically an array of strings: ["0x123...", "0x456..."]. Not applicable to legacy transactions
Transaction#sign(privateKey: string | Uint8Array): Promise<Transaction> — creates new transaction with same data, but signed by following private key
Transaction#recoverSenderPublicKey(): string — recovers sender's public key from signed transaction

Transaction Properties

isSigned: boolean - whether tx is signed with private key
gasPrice: bigint - legacy wei/gas
maxFeePerGas: bigint, maxPriorityFeePerGas: bigint - eip1559 wei/gas
amount: bigint - amount (aka value) in wei
fee: bigint - fee in wei (maxFeePerGas * gasLimit or gasPrice * gasLimit)
upfrontCost: bigint - amount + fee in wei, combined
to: string - address that receives the tx
nonce: number - account's nonce
sender: string - address that sends the tx. Only signed txs have the field
hash: string - signed tx hash used in block explorers. Example: 50b6e7b58320c885ab7b2ee0d0b5813a697268bd2494a06de792790b13668c08
raw: Object - raw transaction's data with fields encoded as strings

License

MIT License

Usage no npm install needed!