Friday, March 29, 2019

HTTP Signature support in Apache CXF

Apache CXF provides support for the HTTP Signatures draft spec since the 3.3.0 release. Up to this point, JAX-RS message payloads could be signed using either XML Security or else using JOSE. In particular, the JOSE functionality can be used to also sign HTTP headers. However it doesn't allow the possibility to sign the HTTP method and Path, something that HTTP Signature supports. In this post we'll look at how to use HTTP Signatures with Apache CXF.

I uploaded a sample project to github to see how HTTP Signature can be used with CXF:
  • cxf-jaxrs-httpsig: This project contains a test that shows how to use the HTTP Signature functionality in Apache CXF to sign a message to/from a JAX-RS service.

1) Client configuration

The client configuration to both sign the outbound request and verify the service response is configured in the test code:

Two JAX-RS providers are added - CreateSignatureInterceptor creates a signature on the outbound request, and VerifySignatureClientFilter verifies a signature on the response. The keys used to sign the request and verify the response are configured in properties files, that are referenced via the "" and "" configuration tags:

Here we can see that a keystore is being used to retrieve the private key for signing the outbound request. If you wish to retrieve keys from some other source, then instead of using configuration properties it's best to configure the MessageSigner class directly on the CreateSignatureInterceptor.

By default CXF will add all HTTP headers to the signature. In addition, a client will also include the HTTP method and path using the "(request-target)" header. Also if the payload is not empty, it will be digested with the digest added to a "Digest" HTTP header, which is also signed. This provides payload integrity. By default, the signature algorithm is "rsa-sha256", of course it is possible to configure this. A secured request using HTTP signature looks like the following:

2) Service configuration

The service configuration is defined in spring. Two different JAX-RS providers are used on the service side - VerifySignatureFilter is used to verify a signature on the client request, and CreateSignatureInterceptor is used to sign the response message as per the client request.

For more information on how to use HTTP Signatures with Apache CXF, refer to the CXF documentation.

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