Function computeWitnessPkScript

txscript/pkscript.go:254–286

computeWitnessPkScript computes the script of an output by looking at the spending input's witness.

(witness wire.TxWitness)

// computeWitnessPkScript computes the script of an output by looking at the
// spending input's witness.
func computeWitnessPkScript(witness wire.TxWitness) (PkScript, error) {
	// We'll use the last item of the witness stack to determine the proper
	// witness type.
	lastWitnessItem := witness[len(witness)-1]

	var pkScript PkScript
	switch {
	// If the witness stack has a size of 2 and its last item is a
	// compressed public key, then this is a P2WPKH witness.
	case len(witness) == 2 && len(lastWitnessItem) == compressedPubKeyLen:
		pubKeyHash := hash160(lastWitnessItem)
		script, err := payToWitnessPubKeyHashScript(pubKeyHash)
		if err != nil {
			return pkScript, err
		}

		pkScript.class = WitnessV0PubKeyHashTy
		copy(pkScript.script[:], script)

	// For any other witnesses, we'll assume it's a P2WSH witness.
	default:
		scriptHash := sha256.Sum256(lastWitnessItem)
		script, err := payToWitnessScriptHashScript(scriptHash[:])
		if err != nil {
			return pkScript, err
		}

		pkScript.class = WitnessV0ScriptHashTy
		copy(pkScript.script[:], script)
	}

	return pkScript, nil
}

// hash160 returns the RIPEMD160 hash of the SHA-256 HASH of the given data.
func hash160(data []byte) []byte {