Minimal library for Ethereum transactions, addresses and smart contracts.
Check out article ZSTs, ABIs, stolen keys and broken legs about caveats of secure ABI parsing found during development of the library.
Check out all web3 utility libraries: ETH, BTC, SOL
npm install micro-eth-signer
We support all major platforms and runtimes. For Deno, ensure to use npm specifier. For React Native, you may need a polyfill for getRandomValues. If you don't like NPM, a standalone eth-signer.js is also available.
import { addr, amounts, Transaction } from 'micro-eth-signer';
const privateKey = '0x6b911fd37cdf5c81d4c0adb1ab7fa822ed253ab0ad9aa18d77257c88b29b718e';
const senderAddr = addr.fromPrivateKey(privateKey);
const unsignedTx = Transaction.prepare({
to: '0xdf90dea0e0bf5ca6d2a7f0cb86874ba6714f463e',
maxFeePerGas: 100n * amounts.GWEI, // 100 gwei in wei
value: 1n * amounts.ETHER, // 1 eth in wei
nonce: 0n,
});
const tx = unsignedTx.signBy(privateKey); // Uint8Array is also accepted
console.log('signed tx', tx, tx.toHex());
console.log('need total wei', tx.calcAmounts().wei.amountWithFee);
console.log('address is same', tx.sender === senderAddr);
We support legacy, EIP2930, EIP1559 and EIP4844 (Dencun / Cancun) transactions.
import { addr } from 'micro-eth-signer';
const priv = '0x0687640ee33ef844baba3329db9e16130bd1735cbae3657bd64aed25e9a5c377';
const pub = '030fba7ba5cfbf8b00dd6f3024153fc44ddda93727da58c99326eb0edd08195cdb';
const nonChecksummedAddress = '0x0089d53f703f7e0843953d48133f74ce247184c2';
const checksummedAddress = addr.addChecksum(nonChecksummedAddress);
console.log(
checksummedAddress, // 0x0089d53F703f7E0843953D48133f74cE247184c2
addr.verifyChecksum(checksummedAddress), // true
addr.verifyChecksum(nonChecksummedAddress), // also true
addr.fromPrivateKey(priv),
addr.fromPublicKey(pub)
);
import { addr } from 'micro-eth-signer';
const random = addr.random(); // Secure: uses CSPRNG
console.log(random.privateKey, random.address);
// 0x17ed046e6c4c21df770547fad9a157fd17b48b35fe9984f2ff1e3c6a62700bae
// 0x26d930712fd2f612a107A70fd0Ad79b777cD87f6
The transaction sent ERC-20 USDT token between addresses. The library produces a following hint:
Transfer 22588 USDT to 0xdac17f958d2ee523a2206206994597c13d831ec7
import { decodeTx } from 'micro-eth-signer/abi';
const tx =
'0xf8a901851d1a94a20082c12a94dac17f958d2ee523a2206206994597c13d831ec780b844a9059cbb000000000000000000000000dac17f958d2ee523a2206206994597c13d831ec7000000000000000000000000000000000000000000000000000000054259870025a066fcb560b50e577f6dc8c8b2e3019f760da78b4c04021382ba490c572a303a42a0078f5af8ac7e11caba9b7dc7a64f7bdc3b4ce1a6ab0a1246771d7cc3524a7200';
// Decode tx information
deepStrictEqual(decodeTx(tx), {
name: 'transfer',
signature: 'transfer(address,uint256)',
value: {
to: '0xdac17f958d2ee523a2206206994597c13d831ec7',
value: 22588000000n,
},
hint: 'Transfer 22588 USDT to 0xdac17f958d2ee523a2206206994597c13d831ec7',
});
Or if you have already decoded tx:
import { decodeData } from 'micro-eth-signer/abi';
const to = '0x7a250d5630b4cf539739df2c5dacb4c659f2488d';
const data =
'7ff36ab5000000000000000000000000000000000000000000000000ab54a98ceb1f0ad30000000000000000000000000000000000000000000000000000000000000080000000000000000000000000d8da6bf26964af9d7eed9e03e53415d37aa96045000000000000000000000000000000000000000000000000000000006fd9c6ea0000000000000000000000000000000000000000000000000000000000000002000000000000000000000000c02aaa39b223fe8d0a0e5c4f27ead9083c756cc2000000000000000000000000106d3c66d22d2dd0446df23d7f5960752994d600';
const value = 100000000000000000n;
deepStrictEqual(decodeData(to, data, value, { customContracts }), {
name: 'swapExactETHForTokens',
signature: 'swapExactETHForTokens(uint256,address[],address,uint256)',
value: {
amountOutMin: 12345678901234567891n,
path: [
'0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2',
'0x106d3c66d22d2dd0446df23d7f5960752994d600',
],
to: '0xd8da6bf26964af9d7eed9e03e53415d37aa96045',
deadline: 1876543210n,
},
});
// With custom tokens/contracts
const customContracts = {
'0x106d3c66d22d2dd0446df23d7f5960752994d600': { abi: 'ERC20', symbol: 'LABRA', decimals: 9 },
};
deepStrictEqual(decodeData(to, data, value, { customContracts }), {
name: 'swapExactETHForTokens',
signature: 'swapExactETHForTokens(uint256,address[],address,uint256)',
value: {
amountOutMin: 12345678901234567891n,
path: [
'0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2',
'0x106d3c66d22d2dd0446df23d7f5960752994d600',
],
to: '0xd8da6bf26964af9d7eed9e03e53415d37aa96045',
deadline: 1876543210n,
},
hint: 'Swap 0.1 ETH for at least 12345678901.234567891 LABRA. Expires at Tue, 19 Jun 2029 06:00:10 GMT',
});
Decoding the event produces the following hint:
Allow 0xe592427a0aece92de3edee1f18e0157c05861564 spending up to 1000 BAT from 0xd8da6bf26964af9d7eed9e03e53415d37aa96045
import { decodeEvent } from 'micro-eth-signer/abi';
const to = '0x0d8775f648430679a709e98d2b0cb6250d2887ef';
const topics = [
'0x8c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925',
'0x000000000000000000000000d8da6bf26964af9d7eed9e03e53415d37aa96045',
'0x000000000000000000000000e592427a0aece92de3edee1f18e0157c05861564',
];
const data = '0x00000000000000000000000000000000000000000000003635c9adc5dea00000';
const einfo = decodeEvent(to, topics, data);
console.log(einfo);
User explicitly passes built-in function fetch
to enable network access to JSON-RPC web3 node.
import FetchProvider from 'micro-eth-signer/net/provider';
import Chainlink from 'micro-eth-signer/net/chainlink';
const provider = new FetchProvider(thisGlobal.fetch, 'https://nodes.mewapi.io/rpc/eth', {
Origin: 'https://www.myetherwallet.com',
});
const link = new Chainlink(provider);
const btc = await link.coinPrice('BTC');
const bat = await link.tokenPrice('BAT');
console.log({ btc, bat }); // BTC 19188.68870991, BAT 0.39728989 in USD
Btw cool tool, glad you built it!
Uniswap Founder
Swap 12.12 USDT to BAT with uniswap V3 defaults of 0.5% slippage, 30 min expiration.
import { tokenFromSymbol } from 'micro-eth-signer/abi';
import FetchProvider from 'micro-eth-signer/net/provider';
// import Uniswap2 from 'micro-eth-signer/net/uniswap-v2';
import Uniswap3 from 'micro-eth-signer/net/uniswap-v3';
const provider = new FetchProvider(thisGlobal.fetch, 'https://nodes.mewapi.io/rpc/eth', {
Origin: 'https://www.myetherwallet.com',
});
const USDT = tokenFromSymbol('USDT');
const BAT = tokenFromSymbol('BAT');
const u3 = new Uniswap3(provider); // or new UniswapV2(provider)
const fromAddress = '0xd8da6bf26964af9d7eed9e03e53415d37aa96045';
const toAddress = '0xd8da6bf26964af9d7eed9e03e53415d37aa96045';
const swap = await u3.swap(USDT, BAT, '12.12', { slippagePercent: 0.5, ttl: 30 * 60 });
const swapData = await swap.tx(fromAddress, toAddress);
console.log(swapData.amount, swapData.expectedAmount, swapData.allowance);
The ABI is type-safe when as const
is specified:
import { createContract } from 'micro-eth-signer/abi';
const PAIR_CONTRACT = [
{
type: 'function',
name: 'getReserves',
outputs: [
{ name: 'reserve0', type: 'uint112' },
{ name: 'reserve1', type: 'uint112' },
{ name: 'blockTimestampLast', type: 'uint32' },
],
},
] as const;
const contract = createContract(PAIR_CONTRACT);
// Would create following typescript type:
{
getReserves: {
encodeInput: () => Uint8Array;
decodeOutput: (b: Uint8Array) => {
reserve0: bigint;
reserve1: bigint;
blockTimestampLast: bigint;
};
}
}
We're parsing values as:
// no inputs
{} -> encodeInput();
// single input
{inputs: [{type: 'uint'}]} -> encodeInput(bigint);
// all inputs named
{inputs: [{type: 'uint', name: 'lol'}, {type: 'address', name: 'wut'}]} -> encodeInput({lol: bigint, wut: string})
// at least one input is unnamed
{inputs: [{type: 'uint', name: 'lol'}, {type: 'address'}]} -> encodeInput([bigint, string])
// Same applies for output!
There are following limitations:
[...] as const
Check out src/net/ens.ts
for type-safe contract execution example.
We implement RLP in just 100 lines of code, powered by packed:
import { RLP } from 'micro-eth-signer/rlp';
RLP.decode(RLP.encode('dog'));
Simple serialize (SSZ) is the serialization method used on the Beacon Chain. We implement RLP in just 900 lines of code, powered by packed:
import * as ssz from 'micro-eth-signer/ssz';
EIP-712 is not supported yet.
import { addr, messenger } from 'micro-eth-signer';
const { privateKey, address } = addr.random();
const msg = 'noble';
const sig = messenger.sign(msg, privateKey);
const isValid = messenger.verify(sig, msg, address);
Main points to consider when auditing the library:
Web3Provider
createContract(abi)
should create purely offline contractcreateContract(abi, net)
would create contract that calls network using net
, using external interfaceSKIPPED_ERRORS
, which contains list of test vectors from other libs that we skipThe library is cross-tested against other libraries (last update on 25 Feb 2024):
Transaction signature matches noble-curves
sign()
speed,
which means over 4000 times per second on macs.
The first call of sign
will take 20ms+ due to noble-curves secp256k1 utils.precompute
.
To run benchmarks, execute npm run bench
.
Make sure to use recursive cloning for tests:
git clone --recursive https://github.com/paulmillr/micro-eth-signer.git
MIT License
Copyright (c) 2021 Paul Miller (https://paulmillr.com)