Google API - 跨平台客户端凭证身份验证(Google API - Cross platform client credential authentication)

 我们正在使用一个名为LibGdx的框架，它允许您仅使用Java编写跨平台代码。 我们正在为Android和iOS开发。 
 
 我们在Google云中有一个数据存储区，还有一个Google应用程序引擎api，用于与此数据存储进行通信。 
 
 现在我们想要保证这个API，但是找不到有关如何解决这个跨平台问题的良好指导。 由于我们有fb-login和email-login混合使用，我们需要使用客户端凭据（即只允许我们的应用程序与我们的API进行通信）。 
 
 使用.NET，您将发送客户端凭证（客户端ID / Cleint秘密），然后获取访问令牌，但不确定在这种情况下如何处理。 我们没有任何范围或类似的东西，我们只是想确保我们的API不会被任何人调用。 所以一个简单的承载令牌可以解决我们的问题。 只是不知道从哪里开始。 

We are using a framework called LibGdx, which allows you to write cross-platform code using only Java. We are developing for Android and iOS.
 
We have a datastore in Google cloud, as well as an Google app engine api we made to communicate with this datastore.
 
Now we want to secure this API, but cannot find good guidance on how to approach this for cross-platform. Since we have a mix of fb-login and email-login we need to use client credentials (i.e only our app is allowed to communicate with our API).
 
Using .NET you would send client credentials (Client ID/Cleint secret), then get an access token, not sure how to approach that in this scenario. We do not have any scopes or anything like that, we just want to secure our API so it can't just be called by anyone. So a simple Bearer-token would solve our issues. Just not sure where to begin.

原文：https://stackoverflow.com/questions/42745593