There are primarily two ways to authenticate using Google's reCAPTCHA Enterprise in a non-Google cloud environment (we use AWS). Google recommends using Service Accounts along with their Java client. However, this approach strikes me as less preferable than the second way Google suggests we can can authenticate, namely, using Api Keys. Authenticating via an Api Key is easy, and it’s similar to how we commonly integrate with other 3rd party services, except rather than a username and password that we must secure, we have an Api Key that we must secure. Authenticating using Service Accounts, however, requires that we store a Json file on each environment in which we run reCAPTCHA, create an environment variable (GOOGLE_APPLICATION_CREDENTIALS) to point to that file, and then use Google's provided Java client (which leverages the environment variable/Json file) to request reCAPTCHA resources.
If we opt to leverage Api Key authentication, we can use Google’s REST Api along with our preferred Http Client (Akka-Http). We merely include the Api Key in a header that is encrypted as part of TLS in transit. However, if we opt for the Service Accounts method, we must use Google’s Java client, which not only adds a new dependency to our service, but also requires its own execution context because it uses blocking i/o.
My view is that unless there is something that I’m overlooking--something that the Service Accounts approach provides that an encrypted Api Key does not--then we should just encrypt an Api Key per environment.
Our Site Key is locked down by our domain, and our Api Key would be encrypted in our source code. Obviously, if someone were to gain access to our unencrypted Api Key, they could perform assessments using our account, but not only would it be exceedingly difficult for an attacker to retrieve our Api Key, the scenario simply doesn't strike me as likely. Performing free reCAPTCHA assessments does not strike me as among the things that a sophisticated attacker would be inclined to do. Am I missing something? I suppose my question is why would we go through the trouble of creating a service account, using the (inferior) Java client, storing a Json file on each pod, create an environment variable, etc. What does that provide us that the Api Key option does not? Does it open up some functionality that I'm overlooking?
I've successfully used Api Keys and it seems to work fine. I have not yet attempted to use Service Accounts as it requires a number of things that I'm disinclined to do. But my worry is that I'm neglecting some security vulnerability of the Api Keys.
CodePudding user response：
After poring a bit more over the documentation, it would seem that there are only two reasons why you'd want to explicitly choose API key-based authentication over an Oauth flow with dedicated service accounts:
- Your server's execution environment does not support Oauth flows
- You're migrating from reCAPTCHA (non-enterprise) to reCAPTCHA Enterprise and want to ease migration
Beyond that, it seems the choice really comes down to considerations like your organization's security posture and approved authentication patterns. The choice does also materially affect things like how the credentials themselves are provisioned & managed, so if your org happens to already have a robust set of policies in place for the creation and maintenance of service accounts, it'd probably behoove you to go that route.
Google does mention sparingly in the docs that their preferred method for authentication for reCAPTCHA Enterprise is via service accounts, but they also don't give a concrete rationale anywhere I saw.