Thursday 9 June 2022

Integrating Google Cloud reCAPTCHA Enterprise in PHP

Google Cloud reCAPTCHA Enterprise is the successor (?) to reCAPTCHA v3. 

The code snippets Google supplies for integrating reCATPCHA Enterprise in PHP are frustratingly uncohesive and neither a working demo or complete code sample exists (as far as I can find at the time of writing). 

Moreover, the code snippets that are provided were incomplete for my implementation and the number of moving parts (Cloud projects, keys and credentials) is nothing short of overwhelming. 

Given the above, I struggled for some time just get everything working--which is where I'm up to now. So a disclaimer for those of you readers who are proficient PHP developers and who possess a deeper understanding of the Google Cloud Platform, please use this as a starting point only. There may be a better (more refined) approach. 

In terms of the official documentation and the code snippets I refer to above and will discuss in this post, start here:

I should also note I'm working in a basic web hosting environment with PHP installed. It's not a Google environment--think more budget web host ;)


Before you can get started, you'll need to login to the Google Cloud Platform, create a new project if you don't have a suitable already, and create a reCAPTCHA Enterprise key. Save the key somewhere and take note of your Cloud project ID while you're there as we'll need that later. You'll find your project ID on the relevant dashboard card. 

Incidentally, you can follow the link to reCAPTCHA Enterprise in the documentation to get to where you need to be in the Google Cloud Platform (or just navigate to Menu > Security > reCAPTCHA Enterprise). 

Once that's done, you may want to hop into Menu > APIs and services. If the reCAPTCHA Enterprise API isn't already enabled, find it in the library and enable it. While you're here, you'll also want to create credentials. This is where things are still a bit blurry for me but I created both an API key and a service account. The API key isn't used in my final code and it's possibly not necessary. I'm just used to API keys, I guess! 

The service account basically receives a name and ID and is then assigned the reCAPTCHA Agent role (locate reCAPTCAHA Enterprise in the list of products and services and then select the reCAPTCHA Agent role). 

Once the service account exists, I chose to create a key ("Manage keys"). Google will warn you about the risks of downloading service account keys and suggests using Workload Identity Federation--I don't yet know what this is so do you own homework here. I created a new key (ADD KEY > Create new key) as a .json file--you'll be prompted to download/save this file and I'd suggest storing a copy in a safe place as I have yet to find a way to download this same file again in future. 


With that setup done, we now move into the code. The code runs clients side and server side and is comprised of your HTML page (including a form), a couple of scripts in the HEAD tag and some attributes on the form button. And of course the PHP code. 

Be sure to add your reCAPTCHA Enterprise key to both the script tag in the head and the data-sitekey attribute on your button. It's also required in the call to create_assessment() in the PHP code. 

I'll point out that, in my case, I want to trigger a score-based reCAPTCHA assessment when a user submits a form--no sooner and not unecessarily. I'm therefore using the relevant Google examples here, combined into a single, cohesive file. 

The HTML and script source is taken from this page: 

Note the PHP code is slightly modified to include the putenv call, which references the JSON key file we created earlier. You'll also want to drop in your Google Cloud Platform project ID in the call to create_assessment(). 

	<script src=""></script>
	   function onSubmit(token) {
<form id="demo-form" method="post">
<input type="text" />
<button class="g-recaptcha"


require 'google-re/vendor/autoload.php';

use Google\Cloud\RecaptchaEnterprise\V1\RecaptchaEnterpriseServiceClient;
use Google\Cloud\RecaptchaEnterprise\V1\Event;
use Google\Cloud\RecaptchaEnterprise\V1\Assessment;
use Google\Cloud\RecaptchaEnterprise\V1\TokenProperties\InvalidReason;

* Create an assessment to analyze the risk of a UI action.
* @param string $siteKey The key ID for the reCAPTCHA key (See
* @param string $token The user's response token for which you want to receive a reCAPTCHA score. (See
* @param string $project Your Google Cloud project ID
function create_assessment(
  string $siteKey,
  string $token,
  string $project
): void {
  // *** I added this line ***
  // TODO: To avoid memory issues, move this client generation outside
  // of this example, and cache it (recommended) or call client.close()
  // before exiting this method.
  $client = new RecaptchaEnterpriseServiceClient();

  $projectName = $client->projectName($project);

  $event = (new Event())

  $assessment = (new Assessment())

  try {
	  $response = $client->createAssessment(

	  // You can use the score only if the assessment is valid,
	  // In case of failures like re-submitting the same token, getValid() will return false
	  if ($response->getTokenProperties()->getValid() == false) {
		  printf('The CreateAssessment() call failed because the token was invalid for the following reason: ');
	  } else {
		  printf('The score for the protection action is:');

		  // Optional: You can use the following methods to get more data about the token
		  // Action name provided at token generation.
		  // printf($response->getTokenProperties()->getAction() . PHP_EOL);
		  // The timestamp corresponding to the generation of the token.
		  // printf($response->getTokenProperties()->getCreateTime()->getSeconds() . PHP_EOL);
		  // The hostname of the page on which the token was generated.
		  // printf($response->getTokenProperties()->getHostname() . PHP_EOL);
  } catch (exception $e) {
	  printf('CreateAssessment() call failed with the following error: ');

      $_POST['g-recaptcha-response'], // Safety first! Do you trust this code?

Drop all of the above in a file named whatever.php and upload it to your web server. Before any of this will run on your server, you'll need to attend to some dependencies. 

Upload your .json key file alongside your .php file (or put it somewhere else on the server and amend the putenv path in the PHP code). This file may warrant additional protections. 

With that sorted, you need to fetch all of the Google Cloud files the PHP above depends on. You'll likely want to do this using Composer (which needs to be installed on your desktop) and you can then run this command in a command window: 

composer require google/cloud-recaptcha-enterprise

I'll note I'm only fetching the reCAPTCHA Enterprise bits here--not the entire Google Cloud file set. You do you. 

I saved all of the Google files in a directory named google-re, which you'll see referenced in the first line our PHP. Adjust as required. 

A final note for the FileZilla users out there: when uploading the Google dependencies in particular, you may encounter a horrible runtime exception ("Fail to push limit") if you don't configure the FileZilla transfer type as Binary (Transfer > Transfer type > Binary). Refer to the answer to this question for more information:

Run It

And now you should be able to request your page, submit the button. All being well, you'll encounter no exceptions and receive a nice meessage like "The score for the protection action is:0.89999997615814". Use that and other, related assessment information to act accordingly.  

I hope that helps someone!