A data security system for a navigation system comprising an enabling/disabling unit for enabling or disabling a data transfer from a data memory to a data storage unit of the navigation system, an identification unit for identifying an identification code, such as a vehicle or navigation system identification code, and a comparison unit for comparing these identification codes with identification codes stored in the enabling/disabling unit, where the enabling/disabling unit may enable or disable the data transfer responsive to the comparison. If a vehicle or navigation system identification code is not stored in the enabling/disabling unit, a read/write unit writes an identification code retrieved by an identification unit into the enabling/disabling unit.