We assume that the storage system isn?t trusted entirely and end user must be able to control some security functions. Adding security to storage systems leads to performance degradation. In order to achieve good performance, ECFS uses a key management using symmetric cipher instead of public-key approach. ECFS also uses two-phases revocation to decrease the overhead of key revocation. We evaluate the ECFS security based on the set of criteria for evaluating a storage solution [11].