Abstract: A method for providing random numbers for control units communicating via a vehicle network, in which a random number generator having an aggregation component, a storage unit and a distribution component is provided. A plurality of control units each with at least one entropy source are formed. Their raw data are transmitted to the aggregation component via the vehicle network. A quality assurance of the combined raw data from the entropy sources is carried out using only those combined raw data which both occur in a non-deterministic manner and contain a minimum degree of entropy as qualified raw data. The qualified raw data are converted into an aggregated data block by a cryptographic one-way function and securely stored as a random number in the storage unit. The random number stored in the storage unit is transmitted to a control unit via the vehicle network by the distribution component.

Abstract: A method for determining a period in a vehicle using several time sources.

Abstract: A method for improving information security for vehicle-to-X communication, wherein the vehicle-to-X communication is protectable by at least one certificate, wherein the certificate for protecting the vehicle-to-X communication has a validity period of defined length and is provided for storage in a memory of a vehicle, wherein the method is additionally distinguished in that the vehicle uses a communication link for wireless data interchange between the vehicle and a backend system, before expiry of the validity period of the certificate and a change to a validity period of defined length for an updated certificate, to ask the backend system to provide an up-to-date piece of time information for the vehicle. In addition, the invention relates to a corresponding communication apparatus for vehicle-to-X communication.

Abstract: A method for providing random numbers for control units communicating via a vehicle network, in which a random number generator having an aggregation component, a storage unit and a distribution component is provided. A plurality of control units each with at least one entropy source are formed. Their raw data are transmitted to the aggregation component via the vehicle network. A quality assurance of the combined raw data from the entropy sources is carried out using only those combined raw data which both occur in a non-deterministic manner and contain a minimum degree of entropy as qualified raw data. The qualified raw data are converted into an aggregated data block by a cryptographic one-way function and securely stored as a random number in the storage unit. The random number stored in the storage unit is transmitted to a control unit via the vehicle network by the distribution component.

Abstract: A method for determining a period in a vehicle using several time sources.

Abstract: A method for improving information security for vehicle-to-X communication, wherein the vehicle-to-X communication is protectable by at least one certificate, wherein the certificate for protecting the vehicle-to-X communication has a validity period of defined length and is provided for storage in a memory of a vehicle, wherein the method is additionally distinguished in that the vehicle uses a communication link for wireless data interchange between the vehicle and a backend system, before expiry of the validity period of the certificate and a change to a validity period of defined length for an updated certificate, to ask the backend system to provide an up-to-date piece of time information for the vehicle. In addition, the invention relates to a corresponding communication apparatus for vehicle-to-X communication.