Signature Templates

When a contract function has a sig parameter, it needs a cryptographic signature from a private key for the spending transaction. In place of a signature, a SignatureTemplate can be passed, which will automatically generate the correct signature once the transaction is built.

SignatureTemplate

Constructor

new SignatureTemplate(
  signer: Keypair | Uint8Array | string,
  hashtype?: HashType,
  signatureAlgorithm?: SignatureAlgorithm
)

In place of a signature, a SignatureTemplate can be passed, which will automatically generate the correct signature using the signer parameter. This signer can be any representation of a private key, including BCHJS' ECPair, bitcore-lib-cash' PrivateKey, WIF strings, or raw private key buffers. This ensures that any BCH library can be used.

Example

const aliceWif = 'L4vmKsStbQaCvaKPnCzdRArZgdAxTqVx8vjMGLW5nHtWdRguiRi1';
const aliceSignatureTemplate = new SignatureTemplate(aliceWif)

const tx = await contract.functions
  .transfer(aliceSignatureTemplate)
  .to('bitcoincash:qrhea03074073ff3zv9whh0nggxc7k03ssh8jv9mkx', 10000n)
  .send()

The hashtype and signatureAlgorithm options are covered under 'Advanced Usage'.

Advanced Usage

HashType

The default hashtype is HashType.SIGHASH_ALL | HashType.SIGHASH_UTXOS because this is the most secure option for smart contract use cases.

export enum HashType {
  SIGHASH_ALL = 0x01,
  SIGHASH_NONE = 0x02,
  SIGHASH_SINGLE = 0x03,
  SIGHASH_UTXOS = 0x20,
  SIGHASH_ANYONECANPAY = 0x80,
}

note

If you're using "old-style" covenants (using CashScript v0.6.0 or lower), you need to configure HashType.SIGHASH_ALL as the hashtype parameter for the SignatureTemplate.

Example

const wif = 'L4vmKsStbQaCvaKPnCzdRArZgdAxTqVx8vjMGLW5nHtWdRguiRi1';

const signatureTemplate = new SignatureTemplate(
  wif, HashType.SIGHASH_ALL | HashType.SIGHASH_UTXOS
);

SignatureAlgorithm

The signatureAlgorithm parameter determines the cryptographic algorithm used for signing. By default, the modern and compact Schnorr algorithm is used.

export enum SignatureAlgorithm {
  ECDSA = 0x00,
  SCHNORR = 0x01,
}

Example

const wif = 'L4vmKsStbQaCvaKPnCzdRArZgdAxTqVx8vjMGLW5nHtWdRguiRi1';

const hashType = HashType.SIGHASH_ALL | HashType.SIGHASH_UTXOS
const signatureAlgorithm = SignatureAlgorithm.SCHNORR
const signatureTemplate = new SignatureTemplate(wif, hashType,signatureAlgorithm);