AWS API Gateway authentication error IncompleteSignatureException using JWT with Auth0

Question

Where I'm At

I'm currently working through setting up Auth0 delegated authentication for AWS API Gateway. I've followed the documentation and tutorials below with the exception that I have an app in place rather than their example apps:

https://auth0.com/docs/quickstart/spa/angular2/aws

https://auth0.com/blog/2015/11/10/introducing-angular2-jwt-a-library-for-angular2-authentication/

https://auth0.com/docs/client-platforms/angular2

https://auth0.com/docs/integrations/aws-api-gateway/part-2

What is Working

• Auth0 sign on from my Angular2 app is working correctly and I'm getting a token.
• Auth0's AuthHttp component is attaching the bearer token to the Authenticate header when I call the AWS API Gateway.

What is Not Working

• Status 403 response from AWS API Gateway indicating a Cloudfront IncompleteSignatureException; "Authentication header missing equal-sign".

The authentication header is

Authentication: Bearer edJ0e...[I've truncated for brevity]

Could AWS be expecting a different type of authentication which uses key value pairs? How to I tell AWS API Gateway that it should be looking for a JWT?

Answer 1

I'm guessing you have AWS_IAM authentication enabled for your API Gateway endpoint. You need to disable that if you aren't planning to use it. If you plan to use AWS_IAM authentication in addition to JWT then you will have to send the JWT token using a different field.

From part 5 of the Auth0 tutorial you linked:

The final step is to pass the JWT to the method from the browser client. The standard method is with an Authorization header as a bearer token, and you can use this method if you turn off IAM authorization and rely solely upon the OpenID token for authorization (you will also need to map the Authorization header into the event data passed to the AWS Lambda function). If you are using IAM, then the AWS API Gateway uses the Authorization header to contain the signature of the message, and you will break the authentication by inserting the JWT into this header. You could either add a custom header for the JWT, or put it into the body of the message. If you choose to use a custom header, you'll also need to do some mapping for the Integration Request of the POST method

Answer 2

Based on the error message, it sounds like you've configured your API for AWS_IAM authentication. This requires your request be signed with AWS Signature Version 4.

In order to execute API Gateway functions you will need to do 1 of 3 things:

1. Get AWS credentials via IAM/STS as noted in the auth0 example and use those to sign your request.
2. As noted in Mark B's answer, follow the instructions in step 5 of the tutorial from auth0 and disable AWS_IAM auth and do the validation inside your Lambda.
3. Switch to use a custom authorizer to validate the JWT directly at the API Gateway layer. This would require you to take the code Auth0 provides to validate the token then build your own authorizer result.