The Wisebed wireless sensor network testbed provides a federated experimentation facility covering several European universities. For scalable management of access control we have designed and implemented a single-sign-on and attribute-based authentication and authorization infrastructure based on the Shibboleth software, which has been developed by the Internet2 Middleware Initiative. Shibboleth is usually used for protecting browser-based access of web resources. We have designed and implemented an extension to protect web services using the Simple Object Access Protocol. This extension allows both user and machine authentication for web services. As a proof of concept, we implemented a complete reservation system for sensor nodes in the Wisebed test-bed federation. Two different user interfaces based on a web page and an iPhone application have been implemented. Although implemented for Shibboleth, the architecture can be easily adapted to other authentication and authorization infrastructures.