​​Using Amazon Cognito to Authenticate Players for a Game Backend Service:

https://aws.amazon.com/blogs/gametech/using-amazon-cognito-to-authenticate-players-for-a-game-backend-service/

A: Game client make REST API call to unauthenticated endpoint to invoke Login Lambda function with username and password in JSON body.
B: Login Lambda function uses username and password to authenticate with Amazon Cognito user pool and obtains IdToken.
C: Login Lambda function sends IdToken back to game client through the API Gateway.
D: Game client makes a REST API call to Amazon API Gateway which will validate the IdToken with the Cognito authorizer. API Gateway will then invoke the backend service Lambda function.

#Cognito