Data backup in a vehicle, where a datum is generated by a function implemented on a first control device of the vehicle. The securing of the datum generated is determined using the configuration data stored in a first control device. If the datum generated is to be protected, it is cryptographically marked and/or encrypted. The cryptographically marked and/or encrypted datum is stored in a memory of the first control device. In addition the cryptographically marked and/or encrypted datum or a value derived therefrom is sent over an electronic network of the vehicle to at least one second control device, received by the latter and stored in a memory of the second control device.