A method for a manipulation protection of useful data packets to be transmitted via a bus system between at least two system components, wherein the system components include a signing and signing test unit by which data packets can be generated and tested. A first one of the system components generates an independent protective data packet with protective information for a useful data packet to be transmitted via the bus system, which protective data packet is independent of this useful data packet but, can be allocated unambiguously to it, after which the generated protective data packet is sent out separately from the associated useful data packet via the bus system to the second one of the system components and a verification of the authenticity of the useful data packet to be transmitted is effected by the transmitted protective data packet by the second one of the system components.