eCash

driver

ecash

curve

secp256k1

address formats

legacy P2PKH in CashAddr

SLIP-44 coin

899'

Load it

import { useBlockchain, blockchains } from "@agntn/keys";

const xecChain = useBlockchain(await blockchains.ecash()());
const testnet = useBlockchain(await blockchains.ecash({ network: "testnet" })());

Mainnet and testnet only, anything else throws in the constructor. Regtest has its own ecregtest prefix, and there's no driver for it.

The address

eCash split off Bitcoin Cash in 2020 and kept the address format. The hash is Bitcoin's, RIPEMD160(SHA256(pubkey)), the version byte and the 40-bit checksum are CashAddr's. What changes is the prefix, and since the checksum is taken over the prefix, the rest of the string changes with it.

const privateKey = "0000000000000000000000000000000000000000000000000000000000000001";
const publicKey = xecChain.getKeyPublic(privateKey);

xecChain.getAddress(publicKey); // ecash:qp63uahgrxged4z5jswyt5dn5v3lzsem6cacy2kzvq
testnet.getAddress(publicKey); // ectest:qp63uahgrxged4z5jswyt5dn5v3lzsem6cmn623003

Put that next to bitcoincash:qp63uahgrxged4z5jswyt5dn5v3lzsem6cy4spdc2h. The payload is the same up to the last eight characters, the checksum. Same key, same hash, and Bitcoin shows it as 1BgGZ9tcN4rm9KBzDn7KprQz87SZ26SAMH.

legacy is the only type and it means pay to pubkey hash, written as CashAddr. Ask for "p2sh", "segwit" or anything else and getAddress throws a RangeError, for the same reason as on Bitcoin Cash: Bitcoin's p2sh type wraps a segwit program, and there's no segwit here.

Validation

xecChain.validateAddress("ecash:qp63uahgrxged4z5jswyt5dn5v3lzsem6cacy2kzvq"); // true
xecChain.validateAddress("qp63uahgrxged4z5jswyt5dn5v3lzsem6cacy2kzvq"); // true, prefix left off
xecChain.validateAddress("bitcoincash:qp63uahgrxged4z5jswyt5dn5v3lzsem6cy4spdc2h"); // false

It decodes CashAddr the same way the Bitcoin Cash driver does: optional prefix, one case over the whole string, checksum under the driver's own prefix. The difference is what counts as payable. Bitcoin ABC turns two things into a destination, a 20 byte key hash under type 0 and a 20 byte script hash under type 1, and nothing else. The token types and the 32 byte script hashes that CashTokens brought to Bitcoin Cash came after the split, so a z... or r... payload under ecash: checksums fine and still comes back false.

Base58 is refused too. Its bytes say Bitcoin.

Mnemonics

BIP32 on m/44'/899'/account'/change/index, the coin type SLIP-0044 gives XEC and the one Electrum ABC and Trezor use. Not every wallet agrees. Cashtab walks m/44'/1899'/0'/0/0, and wallets made before the split walk Bitcoin Cash's m/44'/145'. deriveHDWallet takes whatever path you give it, so pass the one your wallet used.

const mnemonic =
  "abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about";

xecChain.deriveHDWallet(mnemonic, "m/44'/899'/0'/0/0").address;
// ecash:qpluxjhhlxfjwsymf9nmctvsdrwzwygadsh2pq0ang
xecChain.deriveHDWallet(mnemonic, "m/44'/145'/0'/0/0").address;
// ecash:qqyx49mu0kkn9ftfj6hje6g2wfer34yfnqdxfumtxd, what bip_utils gives on that path

WIF is Bitcoin's, prefix 0x80. encodeWIF(privateKey, { chain: "bitcoin" }) gives the string an eCash wallet imports.

Signing

This is where eCash and Bitcoin Cash part ways. Bitcoin ABC signs under "\x16eCash Signed Message:\n", not Bitcoin's preamble. The digest is built the usual way, compact size lengths and double SHA-256, but with a different preamble the hash is different. A Bitcoin Cash signature doesn't verify here and the other way around.

The signature is 64 bytes of r||s hex. A signature from ecash-lib verifies, but don't expect the same bytes from the same key, because ecash-lib picks a different nonce. { recovered: true } throws, like on Bitcoin, since the node's recoverable form is base64 with a header byte.

Where it lives

src/blockchains/ecash.ts has the prefixes, the hash lengths Bitcoin ABC pays to and the preamble. Everything else comes from AbstractCashAddrBlockchain in src/utils/bitcoin.ts, which it shares with Bitcoin Cash. The CashAddr codec is in src/utils/cashaddr.ts.