Code:
namespace Bitcoin\Signature;
use Bitcoin\Crypto\Hash;
use Bitcoin\Util\Buffer;
use Bitcoin\Util\Parser;
use Bitcoin\Script\Script;
use Bitcoin\Transaction\TransactionInterface;
use Bitcoin\Transaction\TransactionOutputInterface;
/**
* Class SigHashBuilder
* @package Bitcoin
*/
class SignatureHash implements SignatureHashInterface
{
/**
* @var TransactionInterface
*/
protected $transaction;
/**
* @var TransactionInterface
*/
protected $copy;
/**
* @param TransactionInterface $transaction
*/
public function __construct(TransactionInterface $transaction)
{
$this->transaction = $transaction;
}
/**
* @return TransactionInterface
*/
public function getTransaction()
{
return $this->transaction;
}
/**
* Calculate the hash of the current transaction, when you are looking to
* spend $txOut, and are signing $inputToSign. The SigHashType defaults to
* SIGHASH_ALL, though SIGHASH_SINGLE, SIGHASH_NONE, SIGHASH_ANYONECANPAY
* can be used.
*
* @param TransactionOutputInterface $txOut
* @param $inputToSign
* @param int $sighashType
* @return Buffer
* @throws \Exception
*/
public function calculateHash(TransactionOutputInterface $txOut, $inputToSign, $sighashType = SignatureHashInterface::SIGHASH_ALL)
{
$this->copy = $this->getTransaction();
$inputs = &$this->copy->getInputsReference();
$outputs = &$this->copy->getOutputsReference();
if ($inputToSign > count($inputs)) {
throw new \Exception('Input does not exist');
}
// Default SIGHASH_ALL procedure: null all input scripts
for ($i = 0; $i < count($inputs); $i++) {
$inputs[$i]->setScriptBuf(new Buffer());
}
$inputs[$inputToSign]->setScript($txOut->getScript());
if ($sighashType & 31 == SignatureHashInterface::SIGHASH_NONE) {
// Set outputs to empty vector, and set sequence number of inputs to 0.
$outputs = array();
for ($i = 0; $i < count($inputs); $i++) {
if ($i != $inputToSign) {
$inputs[$i]->setSequence(0);
}
}
} else if ($sighashType & 31 == SignatureHashInterface::SIGHASH_SINGLE) {
// Resize output array to $inputToSign + 1, set remaining scripts to null,
// and set sequence's to zero.
$nOutput = $inputToSign;
if ($nOutput >= count($outputs)) {
throw new \Exception("SignatureHash->calculateHash(): nOutput $nOutput is out of range");
}
// Resize..
$outputs = array_slice($outputs, 0, ($nOutput+1));
// Set to null
for ($i = 0; $i < $nOutput; $i++) {
$outputs[$i]->setScript(new Script());
}
// Let the others update at will
for ($i = 0; $i < count($outputs); $i++) {
if ($i != $inputToSign) {
$inputs[$i]->setSequence(0);
}
}
}
// This can happen regardless of whether it's ALL, NONE, or SINGLE
if ($sighashType & 31 == SignatureHashInterface::SIGHASH_ANYONECANPAY) {
$input = $inputs[$inputToSign];
$inputs = array($input);
}
// Serialize the TxCopy and append the 4 byte hashtype (little endian);
$txParser = new Parser($this->copy->serialize('hex'));
$txParser->writeInt(4, $sighashType, true);
$hash = Hash::sha256d($txParser->getBuffer()->serialize());
$buffer = Buffer::hex($hash);
return $buffer;
}
}
