Bitcoin / Litecoin

Bitcoin and Litecoin chains support the following signature kinds:

• Psbt, partially signed bitcoin transaction, or PSBT.

• Bip322, generic message defined in BIP-322.

PSBT

Signs a partially signed bitcoin transaction.

Field	Description	Type - Optional
blockchainKind	Bitcoin	String
kind	Psbt	String
psbt	The hex encoded PSBT.	String

{
  "blockchainKind": "Bitcoin",
  "kind": "Psbt",
  "psbt": "0x70736274ff0100710200000001ca17431a33a13d3ef8bfb041c8546071f9d3a609abe3c91efbed83265e1426730100000000ffffffff02e803000000000000160014a40a65b46ff36c53f1afb8e35e25a4c0bcfc9979d6d1150000000000160014237ad8ba2ffd992f6ebc7ab388e77f00fc87d1c9000000000001011f54d6150000000000160014237ad8ba2ffd992f6ebc7ab388e77f00fc87d1c9000000"
}

Typescript Example with BitcoinJS

First install the BitcoinJS SDK. You can find the full documentation here: https://github.com/bitcoinjs/bitcoinjs-lib

Here a code sample to generate a signature via the Dfns TypeScript SDK:

import { networks, payments, Psbt } from 'bitcoinjs-lib'
import axios from 'axios'

const walletId = 'wa-6lbfv-9esgj-xxxxxxxxxxxxxxxx'
const wallet = await dfnsClient.wallets.getWallet({ walletId })
const publicKey = Buffer.from(wallet.signingKey.publicKey, 'hex')

const network = networks.testnet
const { address } = payments.p2wpkh({
  pubkey: publicKey,
  network,
})

const txid = '87872516c6e93f136fc6c493c7172596b11c695e27889de7532abffcac2a4b5e'
const n = 1
const utxo = (
  await axios.post(BITCOIN_NODE_URL, {
    jsonrpc: '2.0',
    id: 'gettxout',
    method: 'gettxout',
    params: [txid, n, false],
  })
).data.result

const balance = utxo.balance * 100000000
const amount = 1
const fee = 150

const psbt = new Psbt({ network })
psbt.addInput({
  hash: txid,
  index: n,
  witnessUtxo: {
    script: Buffer.from(utxo.scriptPubKey.hex, 'hex'),
    value: balance,
  },
})

psbt.addOutput({
  address: 'tb1q5s9xtdr07dk98ud0hr34ufdycz70exte2kehm2',
  value: amount,
})

psbt.addOutput({
  address,
  value: balance - amount - fee,
})

const res = await dfnsClient.wallets.generateSignature({
  walletId,
  body: { kind: 'Psbt', psbt: `0x${psbt.toHex()}` },
})

BIP-322

Signs a generic message using BIP-322. Note: signing payload construction depends on the targeted blockchain. Therefore it's tied to a specific network rather than the blockchain kind.

Field	Description	Type - Optional
network	A supported Bitcoin network.	String
kind	Bip322	String
message	The generic message hex encoded.	String
format	Either Simple or Full. Defaults to Simple if not present. The formatted signature is returned in the signedData field in the response.	String (optional)

{
  "network": "Bitcoin",
  "kind": "Bip322",
  "message": "0x49206c6f76652044666e73"
}