mloureiro/googleSignedUrls.php

## googleSignedUrls.php
<?
/**
 * Google Bucket GET file with signed string example
 */

require_once("vendor/autoload.php");

/*
 * Helper Methods
 */

function googleBuildConfigurationString($method, $expiration, $file, array $options = [])
{
  $allowedMethods = ['GET', 'HEAD', 'PUT', 'DELETE'];

  // initialize
  $method = strtoupper($method);
  $contentType = $options['Content_Type'];
  $contentMd5 = $options['Content_MD5']
    ? base64_encode($options['Content_MD5'])
    : '';
  $headers = $options['Canonicalized_Extension_Headers']
    ? $options['Canonicalized_Extension_Headers'] . PHP_EOL
    : '';
  $file = $file ? $file : $options['Canonicalized_Resource'];

  // validate
  if(array_search($method, $allowedMethods) === false)
  {
    throw new RuntimeException("Method '{$method}' is not allowed");
  }
  if(!$expiration)
  {
    throw new RuntimeException("An expiration date should be provided.");
  }

  return <<<TXT
{$method}
{$contentMd5}
{$contentType}
{$expiration}
{$headers}{$file}
TXT;
}


function googleSignString($p12FilePath, $string)
{
  $certs = [];
  if (!openssl_pkcs12_read(file_get_contents($p12FilePath), $certs, 'notasecret'))
  {
    echo "Unable to parse the p12 file. OpenSSL error: " . openssl_error_string(); exit();
  }

  $RSAPrivateKey = openssl_pkey_get_private($certs["pkey"]);
  $signed = '';
  if(!openssl_sign( $string, $signed, $RSAPrivateKey, 'sha256' ))
  {
    error_log( 'openssl_sign failed!' );
    $signed = 'failed';
  }
  else
  {
    $signed = base64_encode($signed);
  }

  return $signed;
}

function googleBuildSignedUrl($serviceEmail, $file, $expiration, $signature)
{
  return "http://storage.googleapis.com{$file}"
    . "?GoogleAccessId={$serviceEmail}"
    . "&Expires={$expiration}"
    . "&Signature=" . urlencode($signature);
}

/*
 * Initialization
 */

$serviceEmail = '<service-email>';
$p12FilePath = 'keys/google.certificate.p12';
$expiration = (new DateTime())->modify('+3hours')->getTimestamp();
$bucket = 'example';
$fileToGet = 'video.mp4';

/*
 * Building!
 */

$file = "/{$bucket}/{$fileToGet}";
$string = googleBuildConfigurationString('GET', $expiration, $file);
$signedString = googleSignString($p12FilePath, $string);
$signedUrl = googleBuildSignedUrl($serviceEmail, $file, $expiration, $signedString);

?>
<html>
<body>
  <style>pre {background: #eee;}</style>

  <h2>String</h2>
  <pre><?= $string ?></pre>

  <br>

  <h2>Final Url</h2>
  <pre><?= $signedUrl ?></pre>

  <br>

  <video controls>
    <source src="<?= $signedUrl ?>" type="video/mp4">
  </video>

</body>
</html>
	<?
	/**
	* Google Bucket GET file with signed string example
	*/

	require_once("vendor/autoload.php");

	/*
	* Helper Methods
	*/

	function googleBuildConfigurationString($method, $expiration, $file, array $options = [])
	{
	$allowedMethods = ['GET', 'HEAD', 'PUT', 'DELETE'];

	// initialize
	$method = strtoupper($method);
	$contentType = $options['Content_Type'];
	$contentMd5 = $options['Content_MD5']
	? base64_encode($options['Content_MD5'])
	: '';
	$headers = $options['Canonicalized_Extension_Headers']
	? $options['Canonicalized_Extension_Headers'] . PHP_EOL
	: '';
	$file = $file ? $file : $options['Canonicalized_Resource'];

	// validate
	if(array_search($method, $allowedMethods) === false)
	{
	throw new RuntimeException("Method '{$method}' is not allowed");
	}
	if(!$expiration)
	{
	throw new RuntimeException("An expiration date should be provided.");
	}

	return <<<TXT
	{$method}
	{$contentMd5}
	{$contentType}
	{$expiration}
	{$headers}{$file}
	TXT;
	}


	function googleSignString($p12FilePath, $string)
	{
	$certs = [];
	if (!openssl_pkcs12_read(file_get_contents($p12FilePath), $certs, 'notasecret'))
	{
	echo "Unable to parse the p12 file. OpenSSL error: " . openssl_error_string(); exit();
	}

	$RSAPrivateKey = openssl_pkey_get_private($certs["pkey"]);
	$signed = '';
	if(!openssl_sign( $string, $signed, $RSAPrivateKey, 'sha256' ))
	{
	error_log( 'openssl_sign failed!' );
	$signed = 'failed';
	}
	else
	{
	$signed = base64_encode($signed);
	}

	return $signed;
	}

	function googleBuildSignedUrl($serviceEmail, $file, $expiration, $signature)
	{
	return "http://storage.googleapis.com{$file}"
	. "?GoogleAccessId={$serviceEmail}"
	. "&Expires={$expiration}"
	. "&Signature=" . urlencode($signature);
	}

	/*
	* Initialization
	*/

	$serviceEmail = '<service-email>';
	$p12FilePath = 'keys/google.certificate.p12';
	$expiration = (new DateTime())->modify('+3hours')->getTimestamp();
	$bucket = 'example';
	$fileToGet = 'video.mp4';

	/*
	* Building!
	*/

	$file = "/{$bucket}/{$fileToGet}";
	$string = googleBuildConfigurationString('GET', $expiration, $file);
	$signedString = googleSignString($p12FilePath, $string);
	$signedUrl = googleBuildSignedUrl($serviceEmail, $file, $expiration, $signedString);

	?>
	<html>
	<body>
	<style>pre {background: #eee;}</style>

	<h2>String</h2>
	<pre><?= $string ?></pre>

	<br>

	<h2>Final Url</h2>
	<pre><?= $signedUrl ?></pre>

	<br>

	<video controls>
	<source src="<?= $signedUrl ?>" type="video/mp4">
	</video>

	</body>
	</html>