ecash-lib

Library for eCash transaction building.

• Compatible: Works on the browser using webpack, on NodeJS, jest etc.
• Fast: Accelerated using the highly optimized secp256k1 library compiled to WebAssembly
• Simple to use: Describe the tx to build in one TxBuilder object, and build the tx with just one sign call
• SLP/ALP enabled: Functions to build the SLP/ALP eMPP scripts
• Flexible: The "Signatory" mechanism can accommodate anything from simple wallet transfers to complex Script covenants, e.g. eCash Agora
• Schnorr: eCash lib supports Schnorr and ECDSA signatures
• Precise leftover ("change") computation: The tx size estimator will be exact for Schnorr signatures and very close for ECDSA signatures, even for complex scripts

Usage

This library works for both browser and NodeJS.

Installation

npm install --save ecash-lib

Usage

Here's how to sign your first transaction:

import {
    Ecc,
    P2PKHSignatory,
    Script,
    TxBuilder,
    fromHex,
    shaRmd160,
    toHex,
    ALL_BIP143,
} from 'ecash-lib';

const walletSk = fromHex(
    'e6ae1669c47d092eff3eb652bea535331c338e29f34be709bc4055655cd0e950',
);
const walletPk = new Ecc().derivePubkey(walletSk);
const walletPkh = shaRmd160(walletPk);
const walletP2pkh = Script.p2pkh(walletPkh);
// TxId with unspent funds for the above wallet
const walletUtxo = {
    txid: '0000000000000000000000000000000000000000000000000000000000000000',
    outIdx: 0,
};
// Tx builder
const txBuild = new TxBuilder({
    inputs: [
        {
            input: {
                prevOut: walletUtxo,
                signData: {
                    sats: 1000n,
                    outputScript: walletP2pkh,
                },
            },
            signatory: P2PKHSignatory(walletSk, walletPk, ALL_BIP143),
        },
    ],
    outputs: [
        {
            sats: 0n,
            script: new Script(fromHex('6a68656c6c6f')),
        },
        walletP2pkh,
    ],
});
const tx = txBuild.sign({ feePerKb: 1000n, dustSats: 546n });
const rawTx = tx.ser();
console.log(toHex(rawTx));

Changelog

• 0.1.1 - Validation that feePerKb is an integer
• 0.1.2 - Upgrade dependencies D16373
• 0.1.3 - Export slpAmount function D16379
• 0.2.0 - Add Script.fromAddress method to convert cashaddr addresses to Script
• 0.2.1 - Fix fee estimation for signatories that depend on tx outputs D16673
• 1.0.0 - (Breaking change) Modify GenesisInfo so that auth and data types match D17194
• 1.0.1 - Include ecashaddrjs and chronik-client installations from npmjs instead of local, to prevent need for peer dependencies D17215
• 1.1.0 - Add support for the original pre-UAHF Bitcoin signatures, so we can sign transactions for other blockchains like BTC/DOGE/... D17255
• 1.2.0 - Add Address class for cashaddr and legacy addresses. D17269
• 1.2.1 - Patch type check causing txBuilder txs using change to fail in NodeJS environments D17461
• 1.3.0 - Add toHex() method to Script to allow simple conversion to hex string D17527
• 1.4.0 - Add HdNode, entropyToMnemonic, mnemonicToEntropy and mnemonicToSeed to complete wallet functionality D17619
• 1.4.1 - Patch import in mnemonic.ts D17621
• 1.5.0 - Support custom WASM URL and module D17622
• 1.5.1 - Address.withPrefix() returns same prefix if unchanged (instead of throwing an error) D17623
• 2.0.0 - Remove initWasm, auto-load the WebAssembly instead. Remove unneeded ecc parameters, esp. in TxBuilder.sign and HdNode.fromSeed D17639 D17640
• 2.1.0 - Add signRecoverable and recoverSig to Ecc D17667
• 3.0.0 - Improve types and shapes in line with chronik proto updates D17650
• 3.1.0 - Add methods for signing and verifying messages D17778
• 3.2.0 - Add method for parsing pushes from an EMPP OP_RETURN D18057