Data security system for a vehicle navigation system and method for transmitting navigation data to the vehicle navigation system

The invention relates to a data security system for a vehicle navigation system (110), comprising enabling/disabling means (140) for enabling or disabling a data transfer from a data memory (130) comprising navigation data (131) to be transmitted to a data storing unit (111) of the navigation system, means (113) for identifying a vehicle or navigation system identification code, a comparison unit (114) for comparing a vehicle or navigation system identification code stored on the enabling/disabling means to the respective identification code of the vehicle or navigation system identified by the means (113) for identifying the identification code, wherein the enabling/disabling means enables or disables the data transfer in dependence on the comparison.