Ensuring the security of services in a distributed system requires the collaboration of all the elements involved in providing this service. In this paper we present how the security of collaborative distributed services is ensured in the Java Card TM1 Grid project carried out at LaBRI, Laboratoire Bordelais de Recherche en Informatique. The aim of this project is to build a hardware platform and the associated software components to experiment on the security features of distributed applications. To achieve this goal, we use the hardware components that offer the highest security level, i.e. smart cards. We do not pretend that the resulting platform can be efficient, but we believe that it is a good testbed to experiment on the security features that one would require for real distributed applications. The kind of applications (and the services they use) that we run on our platform are those that require a high level of confidentiality regarding their own binary code, the input data that they handle, and the results that they produce. This paper focuses on the collaboration aspect of the secure services in our platform.