An approach to multiprotocol ACL implementation with guaranteed protocol compliance is described. In one approach, a method of access rights validation for a multiprotocol supported file server is detailed. The method involves receiving a request to store a file with a security descriptor and storing the security descriptor in an extended attribute associated with the file. Subsequently, the security descriptor is expanded to extract a set of ACEs. Access to the file can then be validated against the ACEs expanded from the security descriptor according to the specifications of the protocol that created the security descriptor.