Thursday, March 21, 2019

Using authorization with JWT tokens in Apache CXF

JSON Web Tokens (JWT) have been covered extensively on this blog (for example here). In this post we will cover how JWT tokens can be used for authorization when sent to a JAX-RS web service in Apache CXF. In particular, we will show how Apache CXF 3.3.0 supports claims based access control with JWT tokens.

1) JWT with RBAC

JWT tokens can be used for the purpose of authentication in a web service context, by verifying the signature on the token and taking the "sub" claim as the authenticated principal. This assumes no proof of possession of the token, something we will revisit in a future blog post. Once this is done we have the option of performing an authorization check on the authenticated principal. This can be done easily via RBAC by using a claim in the token to represent a role.

Apache CXF has a SimpleAuthorizingInterceptor class, which can map web service operations to role names. If the authenticated principal is not associated with the role that is required to access the operation, then an exception is thrown. Here is an example of how to configure a JAX-RS web service in CXF with the SimpleAuthorizingInterceptor for JWT:
Here the JwtAuthenticationFilter has been configured with a "roleClaim" property of "role". It then extracts the configured claim from the authenticated token and uses it for the RBAC authorization decision. To see this functionality in action, look at the corresponding test-case in my github repo.

2) JWT with CBAC

Since CXF 3.3.0, we can also use the Claims annotations in CXF (that previously only worked with SAML tokens) to perform authorization checks on requests that contain JWT tokens. This allows us to specify more fine-grained authorization requirements on the token, as opposed to the RBAC approach above. For example, we can annotate our service endpoint as follows:

Here we can see a "role" claim is required which must match either the value "boss" or "ceo". We can enable claims based authorization by adding the ClaimsAuthorizingFilter as a provider of the endpoint, with the "securedObject" parameter being the service implementation:

We can specify multiple claims annotations and combine them in different ways, please see the CXF webpage for more information. To see this functionality in action, look at the corresponding test-case in my github repo.

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