How to manage confidential data in the grid environment is a critical issue because users' data can be saved in untrusted remote storages. This paper introduces a service to store in a secure way and in an encrypted format confidential data (e.g. medical or financial data) on the grid storage elements, the Secure Storage. Moreover, this service solves the insider abuse problem preventing also the administrators of the storage elements to access the confidential data in a clear format. It is fully integrated on the grid Middleware of the EGEE infrastructure, gLite, and has been designed and developed in the context of the TriGrid VL Project.