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.

$3

npm install --save ecash-lib

$3

To sign signatures, you need an "Ecc" instance:

``ts
import { Ecc } from 'ecash-lib';
const ecc = new Ecc();
`

Note: You should only call this function once, as it's fairly expensive to setup, it internally precomputes some elliptic curve field elements, which takes some time

$3

Now you're ready to sign your first transactions:

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

// Build a signature context for elliptic curve cryptography (ECC)
const ecc = new Ecc();
const walletSk = fromHex(
'e6ae1669c47d092eff3eb652bea535331c338e29f34be709bc4055655cd0e950',
);
const walletPk = 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: {
value: 1000,
outputScript: walletP2pkh,
},
},
signatory: P2PKHSignatory(walletSk, walletPk, ALL_BIP143),
},
],
outputs: [
{
value: 0,
script: new Script(fromHex('6a68656c6c6f')),
},
walletP2pkh,
],
});
const tx = txBuild.sign(ecc, 1000, 546);
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