DE102017203725A1 - Device for processing user data in a control device - Google Patents

Abstract

Device (10) for processing user data (11, 12) in a control device (13),
characterized by the following features:
a first data register (14) for data transfer from a main processor (15) of the control unit (13),
a payload data generator (16) connected on the input side to the first data register (14) for generating outgoing payload data (11),
a first multiplexer (17) connected to the input side optionally with the first data register (14) or the user data generator (16) for selecting (18) the outgoing user data (11),
a configuration register (19) connected on the one hand to the main processor (15) and on the other hand to the first multiplexer (17) for controlling the selection (18),
a controller (20) connected to the first multiplexer (17) for controlling a transceiver (21) of the control unit (13),
a user data evaluator (22) connected on the input side to the controller (20) for evaluating incoming user data (12),
a second multiplexer (23) connected to the configuration register (19) and optionally to the controller (20) or the user data evaluator (22) on the input side for selecting (18) the incoming user data (12) and
- An input side to the second multiplexer (23) connected to the second data register (24) for data transfer to the main processor (15).

Description

The present invention relates to a device for processing user data in a control device. The present invention also relates to a corresponding control device and a corresponding field bus, in particular a CAN.

State of the art

Well-known in control and regulation technology is the controller area network (controller area network, CAN) standardized according to ISO 11898-2 for use in road vehicles. CAN is based on a message-oriented protocol in which each message is identified by a unique identifier (ID). Each control unit connected to a CAN independently uses this ID to check the relevance of the messages transmitted via the shared bus and decides on their utilization.

The operation of the control unit in the CAN is a transceiver on the physical layer (physical layer, PHY), which is controlled by a communication controller on the data link layer. The latter in turn can be integrated directly into a microcontroller (μC) whose software processes the message frames or frames of the messages on the application layer.

In DE 10 2015 207 220 A1 A method for generating a secret or key in a network, in particular a CAN, is presented. In this case, the network has at least a first and a second subscriber and a transmission channel between at least the first and the second subscriber. The first and second subscribers may each provide at least a first value and a second value to the transmission channel. The first subscriber or the second subscriber initiate a first subscriber value sequence or a second subscriber value sequence for transmission to the transmission channel which is largely synchronous with one another. On the basis of information about the first subscriber value sequence or the second subscriber value sequence and on the basis of an overlay value sequence resulting from a superposition of the first subscriber value sequence with the second subscriber value sequence on the transmission channel, the first subscriber or the second subscriber generate a shared secret or a common key. This method is referred to below as PnS, a message exchanged in this frame as a key generation message (KGM).

Disclosure of the invention

The invention provides a device for processing user data in a control device, a corresponding control device and a corresponding field bus, in particular a CAN bus, according to the independent claims.

The proposed approach is based on the recognition that the PnS method is usually implemented in hardware, because the underlying protocol prescribes the timing on the bus, and this protocol can usually only be followed by a digital circuit or with its support , This makes it difficult to add a controller to PnS-independent functions that require or benefit from simultaneous transmission on the bus.

An advantage of the proposed solution is therefore the possibility of changing the format of the payload of a KGM at any time. This makes the implementation of a suitably equipped control unit future-proof, because new findings or requirements could lead to a change in the payload format of the KGM. In particular, in the course of a standardization of PnS, a user data format could be specified, the generation of which is not supported by currently available hardware.

The measures listed in the dependent claims advantageous refinements and improvements of the independent claim basic idea are possible. Thus, according to the invention, the bus can be opened up for new applications in which several control units simultaneously transmit a message. A corresponding embodiment makes it possible to relieve the bus, because for certain tasks, only one data frame must be transmitted. These new applications are not tied to the PnS key generation. Rather, they are other applications that take advantage of the overlaying of multiple data frames to achieve efficiency gains or performance gains.

list of figures

• 1 das Blockschaltbild einer Vorrichtung gemäß einer Ausführungsform der Erfindung.
• 2 die im Rahmen einer Ausführungsform mögliche Authentisierung der Vorrichtung.

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. It shows:

• 1 the block diagram of a device according to an embodiment of the invention.
• 2 the possible authentication of the device in one embodiment.

Embodiments of the invention

In the 1 represented device ( 10 ) allows you to select whether the outgoing user data ( 11 ) of the KGM in the device ( 10 ) or generated by a central processing unit (CPU) 15 ) is provided so that the device ( 10 ) they only by means of a suitable for superimposing data frame transceiver ( 21 ) on the CAN bus ( 25 ) must transmit. The same applies to the incoming user data ( 12 ). Here you can also choose whether the device ( 10 ) processes the received user data or stores it only and a main processor ( 15 ) takes over the processing. In 1 are shown for simplicity only those functions that are necessary to explain the innovations described below.

The software is stored in a configuration register ( 19 ), whether the device ( 10 ) the KGM user data ( 11 ) generate yourself and the received data ( 12 ) should process itself. Depending on the value of the configuration register ( 19 ), a first multiplexer ( 17 ) and a second multiplexer ( 23 ), which control the data flow.

According to a first variant, the KGM user data ( 11 . 12 ) in the device ( 10 ) are self-generated and evaluated. Their payload generators ( 16 ) takes over the generation of the outgoing KGM user data ( 11 ). The software creates random numbers in a first data register ( 14 ). A user data evaluator ( 22 ) takes over the evaluation of the incoming KGM user data ( 12 ) and passes the result data to a second data register ( 24 ). Here, the secret (secret) is stored, which from the incoming user data ( 12 ) was extracted. Dispatch and reception are handled by a CAN controller ( 20 ).

According to a second variant, the outgoing KGM user data ( 11 ) are provided by the software. The software stores the outgoing user data ( 11 ) in the first data register ( 14 ). The device ( 10 ) sends this data without any change. The dispatch is handled by a CAN controller ( 20 ). Similarly, the device receives ( 10 ) the superimposed KGM data frames and stores the incoming payload ( 12 ) unchanged in the second data register ( 24 ). The software finally reads the second data register ( 24 ) and calculates the secret.

The payload format of the KGM can be easily changed in this second variant. For this, only the KGM user data ( 11 . 12 ) are generated and evaluated by software. An adaptation of the KGM payload format may be desirable for various reasons. For example, new findings that allow for improvement or standardization efforts that result in a different payload format may be considered.

In particular, the KGM user data format can be individually adapted in this second variant, so that optional data is transmitted in the context of the KGM for the key establishment. 2 shows this with the example of the authentication of two controllers Alice ( 31 ) and Bob ( 32 ) whose transmitted data frame is at the signal level ( 33 ) of - in 2 not pictured - fieldbus ( 25 overlay). In addition to the subscriber value sequence ( 35 , 36, 37) in the sense of the PnS method, the data frame here comprises a further bit sequence used for authentication ( 38 . 39 ; 39 . 38 ), which differ from Alice ( 31 ) to Bob ( 32 ) is different. While Alice ( 31 ) a bit string ( 38 ) with eg a cryptographic signature followed by a recessive bit sequence ( 39 sends, sends Bob ( 32 ) first a recessive bit sequence ( 39 ) followed by a bit string ( 38 ) with eg a cryptographic signature. Alice 31 ) and Bob ( 32 ) send their signatures ( 38 ) one after another, so that they can be received unchanged. The sent recessive bit sequence ( 39 ) is neutral and changes the data on the bus ( 25 ) Not. The user data ( 11 . 12 ) are in this case according to the CAN protocol of their matching KGM identifier ( 34 ) on the one hand and cyclic redundancy check (CRC), acknowledgment field (acknowledgment, ACK) and end of frame (EOF 40 ) on the other hand.

According to a third variant, the device ( 10 - 1 ) for running a new application that uses overlays of data frames. The software writes the outgoing user data ( 11 ) into the first data register ( 14 ). The device ( 10 ) then transmits a data frame of a preconfigured type with a likewise previously configured ID and length. The incoming user data ( 12 ) stores the device ( 10 ) in the second data register ( 24 ). The software then reads the data from the second data register ( 24 ) and process them.

This third variant proves to be advantageous for all applications that benefit from the superimposition of data frames. Here it is possible that several control units simultaneously transmit a data frame and receive the superimposed data frame. One essential application that can be realized with this is that information from several ECUs can be combined in one CAN frame. By an agreed user data format gets to each Control unit assigned one or more bit positions in which it can send its information. At all other bit positions of the payload, a controller always sends a 1, which corresponds to a neutral "recessive" on the CAN bus. If, for example, the control units want to transmit binary information-for example, 1 for "yes" and 0 for "no" -then each control unit transmits at one of its number corresponding bit position of the user data ( 11 ) a 1 or 0, eg control unit 5 at the bit position 5 , At all other bit positions of the user data ( 11 ), the controllers send a 1 corresponding to a recessive bit which is neutral. The received user data ( 12 ), which is a superposition of the simultaneously sent messages, contains the yes / no information of all control units. On the one hand, this approach reduces the time required for transmission and, on the other hand, relieves the bus system ( 25 ). The information is exchanged very quickly, since in a plurality of n controllers involved only a single - instead of n - data frame is required. The information of all ECUs is contained in a single data frame. Thus, the overlying protocol layers simplify, since without the use of a device according to the invention n data frames would have to be sent and each control device that processes them would have to assign the corresponding n responses to one another. The number of necessary identifiers also decreases from n to 1, because according to the invention all controllers can send data frames with the same identifier.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102015207220 A1 [0004]

Claims (10)

Device (10) for processing user data (11, 12) in a control unit (13), characterized by the following features: - a first data register (14) for data transfer from a main processor (15) of the control unit (13), - an input side with user data generator (16) connected to the first data register (14) for generating outgoing user data (11), - a first multiplexer (17) connected to the first data register (14) or the user data generator (16) for selecting (18) the outgoing user data (11), - a configuration register (19) connected to the main processor (15) and the first multiplexer (17) for controlling the selection (18) and - a controller (20) connected to the first multiplexer (17) for controlling a transceiver (21) of the control unit (13). Device (10) according to Claim 1 , characterized by the following features: a user data evaluator (22) connected on the input side to the controller (20) for evaluating incoming user data (12), one with the configuration register (19) and optionally with the controller (20) or the user data evaluator (22 ) connected second multiplexer (23) for selecting (18) the incoming payload data (12) and - a second input side connected to the second multiplexer (23) second data register (24) for data transfer to the main processor (15). Device (10) according to Claim 2 CHARACTERIZED BY: - the payload data generator (16) is arranged such that the outgoing payload data (11) comprises a particular permutation of particular bits of the first data register (14) and a one's complement of the particular bits of the first data register (14); - The Nutzdatenauswerter (22) is arranged such that certain bits of the second data register (24) each correspond to a non-exclusive disjunction of two specific bits of the incoming payload data (12), wherein the bits are each determined by a bit position. Control unit (13), characterized by the following features: - a device (10) according to one of Claims 1 to 3 - software for generating a random number, - a main processor (15) connected to at least the first data register (14) and the configuration register (19) of the device (10) for executing the software, and - one to the controller (20) of the device (10) connected transceiver (21) for connection to a fieldbus (25). Control unit (13) after Claim 4 characterized by the following features: - the software is arranged to configure the configuration register (19) such that the controller (20) is connected to the payload data generator (16) and - the software is set up to store the random number in the first data register (14) store. Control unit (13) after Claim 4 CHARACTERIZED BY the following features: the software is arranged to configure the configuration register (19) such that the first controller (20) is connected to the first data register (14) and the software is set up to provide a particular permutation of particular bits Random number and a one's complement of the specific bits of the random number in the first data register (14) store, the bits are each determined by a bit position. Control unit (13) after Claim 6 , characterized by the following features: - the software is set up, furthermore, store a unique authentication feature of the control unit (13) in the first data register (14). Control unit (13) after Claim 4 characterized by the following features: - the software is arranged to configure the configuration register (19) such that the controller (20) is connected to the first data register (14), - the software is set up, the outgoing user data (11) in store first data register (14) and - the controller (20) of the device (10) is arranged such that the transceiver (21) the outgoing payload (11) in a data frame of a particular identifier (34), a certain length or a specific Type shipped. Fieldbus (25), characterized by the following feature: - a control unit (13) according to one of Claims 4 to 8th , CAN after Claim 9 ,

Images