Patent Application
20190334998
This application claims priority to German Application No. DE 10 2016 225 436.7, filed on Dec. 19, 2016 with the German Patent and Trademark Office. The contents of the aforesaid application are incorporated herein for all purposes.
The present invention relates to a method, a device and a computer-readable storage medium with instructions for processing measured values from a sensor. In particular, the invention relates to a method, a device and a computer-readable storage medium with instructions for processing measured values from a sensor that render manipulation of the measured values by third parties difficult. The invention moreover relates to a sensor in which such a method is realized, as well as a motor vehicle in which such a method, such a device or such a sensor is used.
In current motor vehicles, an increasing amount of data is collected as a result of digitalization. Given the increasing networking in the world of vehicles and the risk of undesirable high-profile hacker attacks on vehicles, safe transmission of the data is desirable. In addition, efforts in the field of data security in vehicles are also to be anticipated from lawmakers. In order for data to be safely transmitted by the vehicle and to not restrict the usefulness of the data, it is important for data not to be influenceable in an unauthorized manner by third parties. To accomplish this, all communication paths from the respective node to the next node are saved in the vehicle.
Against this background, the document DE 10 2014 001 270 A1 describes a system for protected data transmission in a motor vehicle. To transmit useful data, initially a first codeword is calculated using a transmission time value. Then the useful data are transmitted together with the first codeword to a recipient. The method continues with the calculation of a second codeword using a reception-side time value. If the first codeword and the calculated second codeword do not correspond, the useful data are flagged by the recipient.
It is, however, problematic if data have to be sent from a sensor to a backend outside of the vehicle, for example for further evaluation to detect traffic data or weather data. In this case, various communication nodes are traversed that each must be secured. This results in high costs.
An object of the invention is to present solutions for processing measured values from a sensor that economically renders manipulation of the measured values by third parties difficult.
This object is solved by a method, by a device, and by a computer-readable storage medium with instructions according to the independent claims. Various embodiments of the invention are the discussed in the dependent claims and the following description.
In the FIGS.:
According to one aspect, a method for processing measured values from a sensor comprises the steps:
According to another aspect, a device for processing measured values has:
According to another aspect, a computer-readable storage medium contains instructions that, while being executed by a computer, cause the computer to execute the following steps for processing measured values from a sensor:
According to another aspect, a sensor for detecting a measured value has a memory in which at least one certificate assigned to the sensor for signing the measured value is saved.
In some embodiments, the measured values are directly signed in the sensor. This signing may be retained over the complete communication chain. The sensor may receive at least one certificate for this. This certificate is used in order to sign the measurements that are performed by the sensors before being sent. The signed measured value may be transmitted to the recipient, the authenticity of the measured value may then be first checked by the recipient using the certificate. In some embodiments, the certificate is identical for all sensors of a type. By doing so, it is ensured that the recipient cannot draw any conclusions about a specific sensor using the certificate check. Consequently, no privacy rights are affected by the transmission of the measured values to the recipient. Alternatively and in some embodiments, the certificate is an individual certificate, i.e., each sensor of a type is assigned an unambiguous, unique certificate. That way, the sensor from which data on a detected event is coming may be unambiguously determined. In this manner, it may be ensured that not all of the sensors of a type are insecure following the unauthorized decoding of a certificate by a third party. To guarantee privacy rights in this case as well, the signed measured values are in some embodiments initially transmitted to an intermediate station that checks the authenticity of the measured value using the certificate, and then signs the measured value with a certificate assigned to the intermediate station. The measured value anonymized in this way is then forwarded to the recipient. The recipient is thus again unable to draw any conclusions about a specific sensor.
According to some embodiments, the certificate is saved in a sensor memory. The required certificate for the sensor may for example be introduced in the context of producing the sensor and saved in the memory in a protected manner. By saving the certificate in an internal memory of the sensor, external access to the certificate is thus significantly hindered since the communication between the sensor and memory occurs entirely within the sensor. In some embodiments, the memory is a tamper-proof memory. Tamper protection may be achieved in that the memory only be used by the sensor to which it is assigned, and (read and write) access to the memory is otherwise impossible without destroying the sensor. Reading out the data saved there or an intentional modification by directly contacting the sensor is also impossible from the outside. This category includes, for example, flash memory and random-access memory (RAM), if it is located directly in the sensor, and accessing the sensor is impossible from outside the sensor, including by direct contact. Tamper protection can also be achieved by using read-only memory (ROM).
In some embodiments, the certificate is selected from a group of certificates assigned to the sensor. In addition to a single certificate, a group of certificates may also be used for signing. In this case and in some embodiments, all certificates of the group are saved in a sensor memory. Thus, the number of certificates within the group is minimized so that no conclusions may be drawn about specific sensors. The sensors in some embodiments randomly search for a corresponding certificate and retain it for the entire sensor run time. On the receiver's side, it may then be determined that data on a detected event are coming from different sensors. The only requirement for this is for the sensors to use different certificates. This way, influences by faulty sensors or distortions by third parties may be correspondingly better detected.
In further embodiments, the certificate assigned to the sensor may be exchanged. In some embodiments, it is possible to exchange the certificates at certain intervals in time in a software update. Because of that, it can be ensured that the certificates are only useful for a short duration even if they are decoded by third parties.
In some embodiments, the method, the device, or the sensor are used in an autonomously or manually controlled vehicle, in particular a motor vehicle.
Further features and aspects of the present invention will become apparent from the claims and the following description in conjunction with the FIGS.
In order to better understand the principles of the present technology, embodiments are explained in greater detail below based on the FIGS. It should be understood that the invention is not limited to these embodiments and that the features described may also be combined or modified without departing from the scope of the invention.
The processor 42 may comprise one or more processor units, for example microprocessors, digital signal processors or combinations thereof.
The memories 22, 27, 41 of the described embodiments may have volatile as well as non-volatile memory sections and may comprise a wide range of memory units and storage media, such as hard disks, optical storage media or semiconductor memories.
Another embodiment is described in detail below with reference to
The signing is independent of the bus system, i.e., the sensors are compatible with conventional bus systems such as CAN, CAN-FD (CAN with a flexible data rate) Ethernet, etc. Moreover, the signing is implemented such that it is sufficiently effective to be implemented in software on relatively weak processors. In other words, the signature calculation must be effectively implementable on all sensors so that the available calculation time in the sensor is not excessively restricted. Given a run time of the signature calculation of 100 μs, for example 10% of the available calculation time is no longer available for evaluating the measured values. Moreover, the required memory must be minimal for reasons of cost. It must moreover be taken into consideration that a majority of the input data has a length of ≤64 bytes. Many standard methods such as AES-CMAC (advanced encryption standard—cipher-based message authentication code) [1] or HMAC-SHA256 (HMAC-SHA: hash-based message authentication code—secure hash algorithm) [2] may not be used given these assumptions due to the code size or run time. Consequently, for example MACs (MAC: message authentication code) which are based on ChaCha20/12 [3] with a HAIFA construction (HAIFA: hash iterative framework) [4] are used. With this approach, values of <80 bytes state in RAM and <100 bytes state on the stack may be realized. Depending on the processor, the runtime is between 10 μs and 100 μs per call. One call is sufficient for amounts of useful data up to 32 bytes, an additional call for each additional 48 bytes. In comparison thereto, SHA-256 also requires at least two calls for data volumes of 32 bytes.
The invention has been described in the preceding using various exemplary embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single processor, module or other unit or device may fulfil the functions of several items recited in the claims.
The mere fact that certain measures are recited in mutually different dependent claims or embodiments does not indicate that a combination of these measured cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2016 225 436.7 | Dec 2016 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2017/078578 | 11/8/2017 | WO | 00 |
