FR2712711A1 - Motor vehicle usage control calculator. - Google Patents

Abstract

Computer for controlling the use of a motor vehicle comprising a set of operating members (40) comprising, for managing the operation of at least one of the functional members (40), a processor (2), means for reading (5) portable control means (30) and means (10), for receiving at least one control data from the control means (30), to authorize the processor (2) to manage the organ considered (40), computer in which the reception means (10) comprise descrambling means (13), the processor (2) is arranged to transmit at least one authorization datum (3) for its management of the device (40) to be managed by control means (30) comprising scrambling means (31), the reception means (10) being arranged to unscramble (13) said data, previously scrambled (31) by the control means ( 30), and compare it (12) with the data item (3) transmitted to the control means (30) of the managed organ (40).

Description

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  The present invention relates to a motor vehicle control computer comprising a set of operating members, including a motor, comprising, for managing the operation of a motor vehicle. '' at least one of the functional organs, a processor, means for reading portable control means and means, for receiving at least one control datum from the control means, to authorize the processor to manage the organ in question. The control of the use of a motor vehicle consists in verifying that an individual has good quality to drive it. This quality can be materialized by a mechanical key which makes it possible to unlock an anti-theft device, but this key

is easy to imitate.

  It is also known to use an electronic key. In this case, a keyboard on the vehicle dashboard allows the user to enter a confidential code which, after verification by an electronic circuit associated with the keyboard, is transformed into a control signal authorizing the operation of a control of an essential organ of the vehicle, for example a signal in the form of control data from a computer managing a device for igniting the spark plugs of the engine. In addition to the keyboard, it is also known to provide a smart card reader, which increases protection, since it is necessary to have the

both code and card.

  However, the control data is generally a simple polarity transmitted over a wire, so that the control device, formed by the reader and the smart card, is easily bypassable, since it suffices to disconnect the wire at output and apply the desired polarity to it so that the management calculator

  The vehicle body can operate.

  The present invention aims to render ineffective any direct fraudulent action on the management computer which would aim to simulate the control data coming from a usage control device, with electronic key, of a

motor vehicle.

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  To this end, the invention relates to a computer of the type mentioned above, characterized in that the reception means comprise unscrambling means, the processor is arranged to transmit at least one datum authorizing its management of the organ to be managed by the control means comprising scrambling means, the reception means being arranged to unscramble said data, previously scrambled by the control means, and compare it with the data transmitted to the

  control to authorize the management of the managed body.

  A loop is thus formed comprising the portable control means, for example a smart card, and, when these are not those provided, the data received in return by the computer does not correspond to the expected response data, if although the use of the vehicle is impossible. In particular, the fraudulent disconnection of the receiving circuit from the reading means and its reconnection to any polarity cannot

  simulate the expected scrambled data.

  Advantageously, the reception means comprise a generator

pseudo-random sequences.

  Scrambling and descrambling are carried out according to these sequences and a

  possible simulation of valid scrambled data is thus almost

  impossible, even in the event of prior observation, during authorized uses,

scrambled data.

  Advantageously still, means are provided for memorizing identification data of the computer in order to be compared with data.

  associated portable control means.

  It is thus possible to identify each of the computers belonging to the same production series individually and, for example, to transmit the identification data to the control means so that they compare them with these same data, stored locally, in order to authorize or no scrambling

correct control data.

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  In order to further increase the difficulty of determining, by observing the data exchanged, a scrambling key used for the generator of pseudo-random sequences, it is preferable that the latter comprises at the input an initialization circuit arranged for force the generator outputs in a determined state.

  The invention will be better understood using the following description of the form

  preferred embodiment of the control computer of the invention, with reference to the single figure of the accompanying drawing which is a block representation thereof

functional.

  The control computer for the use of a motor vehicle, referenced 1, is here housed in a car to manage its operating members, and in particular the ignition of the spark plugs of the engine 40 in this example. By operating member, we must understand any member necessary when moving the car, such as engine, steering system, brakes, including

  incorrect operation or blockage prevents the use of the car.

  The computer 1 includes a processor 2, which manages the ignition of the engine 40 indicated above, which is connected to a memory 3 containing data authorizing the use of the car. A bus 4 connects the processor 2 to a reader 5 arranged to receive a smart card 30 and exchange data with it. A bus 6 connects the reader 5 to a reception circuit 10 of the computer 1, an output of which supplies the processor 2 with a signal 11 for authorization to manage the engine 40. It will be understood that the buses 4 and 6

  can be a single bidirectional bus.

  The reception circuit 10 includes a comparator 12 and a set 13 data descrambler comprising a comparator 14, here an exclusive OR logic gate, connected at output to comparator 12 and connected at input to bus 6 as well as to an output of a generator 15 of pseudo-random cyclic sequences of bits. There is also provided here a circuit 16 for initialization of the generator 15 to force the outputs into a state determined by a number here coming from the processor 2. The generator 15 is a counter with a large number of stages associated with gates logic controlled by the output of some of the stages to apply loopback signals to parallel inputs,

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  forcing, previous stages and thus create a pseudo-random count.

  The initialization circuit 16 has, for the sake of clarity, been drawn separately from the generator 15 but is in fact constituted, in this example, parallel input circuits, or forcing, of each of the stages above as well as a clock circuit controlling the activation of these parallel input circuits. Comparator 12 is also connected as an input to a memory 17 containing a third datum associated with the authorization datum contained

in memory 3.

  The comparator 12 is here a parallel comparator, preceded by a serial / parallel buffer register, not shown, for memorizing the bits coming from the comparator 14, and followed by a flip-flop memorizing the signal 11. The comparator 12 could also be a comparator serial, like an exclusive OR logic gate, followed by a serial / parallel register of reception of the result of the comparison of each of the bits of the unscrambled data, exclusive OR 12 producing, in the event of discrepancy of the two bits applied at input, the temporary transition from its output to an inhibition state then detected in the output register to maintain or pass signal 11 to an inhibiting state

  management of engine 40 by processor 2.

  In this example, an assembly 20 for checking the identity of the computer 1 is provided. The assembly 20 includes a read-only memory 21 containing a specific word of identity code, specific to the computer 1, which is applied to a comparator 22, here an exclusive OR gate, connected at input to bus 6 and the output of which is stored in a flip-flop 23 providing a signal 24 for validation of identity. The signal 24 controls the operation of the management of the engine 40 by the processor 2, here being applied to an input of

generator lock 15.

  The smart card 30 includes a circuit 31 for scrambling data, of a structure similar to that of the descrambler 13, and a memory 32 containing

  also the specific word from memory 21.

  For the sake of clarity, the buffer registers necessary for the transmission and reception of data as well as the associated clock synchronization circuits have not been shown. Likewise, the transmission protocol

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  to determine for example the position or the address of the destination circuit of the transmitted data and their nature, for example the use of a marker, or

  token, is well known to those skilled in the art and is not discussed here.

  The operation of the computer 1 will now be explained. In the absence of the smart card 30 in the reader 5, the management authorization signal 11 prevents any management of the ignition 40 by the processor 2. In this example, it is not intended to physically detect the introduction of the smart card 30 into the reader 5, so that the authorization data contained in the memory 3 is transmitted cyclically on the bus 4 by the processor 2, in order to carry out a scan and to detect a response on bus 6 in the event of the presence of the smart card 30. In this case, the scrambling circuit 31 of the smart card 30 receives the authorization data and applies a transformation by scrambling before returning it under form

  scrambled at reception circuit 10, through bus 6.

  The descrambling circuit 13 performs an additional transformation on the scrambled datum which transforms it into identical descrambled datum, if the smart card 30 is valid, with the third datum contained in the memory 17. Thus, the reception circuit 10 can compare the data unscrambled to the authorization data, transmitted by the processor 2 on the bus 4, via the third data associated with the authorization data transmitted. The use of two non-inverse transformations of one another and of a secret association between the authorization data sent (3) and the data expected in return (17) thus makes it possible to have three independent keys. , the discovery of one of which does not affect the secrecy of the other two. Note that the comparison of the authorization data (3) with the unscrambled data could have been carried out by directly comparing these two data to determine a difference, then compared to a difference

planned, stored (17).

  However, provision could have been made for a reverse scrambling transformation from that of the scrambling and, in this case, the memory 17, which, associated

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  with memory 3, constitutes the third key, would have been useless since the comparison of the data transmitted and received in return would have been a simple search for equality, by applying the contents of memory 3 to

  comparator 12, the difference indicated above being zero.

  The purpose of the initialization circuit 16 is to start the pseudo-random cyclic sequence at a determined point in the cycle. This point is determined by a number, which varies from one use to another of the smart card 30. This number, which similarly initializes the scrambler 31, could have been generated by the smart card 30 but is here generated by processor 2 and corresponds here to the number

  seconds of a time base circuit, not shown, of the computer 1.

  It could have been the pseudo-random generator 15, or another, which generates the above number. This number is transmitted by processor 2 to the smart card 30 and to the input of the initialization circuit 16. Thus, the scrambled data varies from one use of the smart card 30 to the next and thus makes more difficult to detect a scrambling / unscrambling algorithm or key

  used by the scrambling 31 and descrambling 13 circuits.

  The identity control assembly 20 receives, via the bus 6, the specific code word from the memory 32 and compares it to that of the memory 21 in order to verify that the computer 1 is properly paired with the smart card 30 wanted. It will be noted that the relative positions of the assembly 20 and of the memory 32 could be swapped, since all the control elements are in a loop 2, 4, 5, 30, 6, 10 and that any logical interruption of this loop

  invalidates the management authorization signal 1 1.

  Provision may also be made for variable data to be included in, or constitute, the authorization data (3). It can be a code word, supplied by the pseudo-random generator 15 or another. It can also be an operating data item for the management of the member 40 managed by the processor 2, which avoids having to store specific authorization data and also makes it possible to have variable authorization data, which further increases the difficulty of fraudulent detection of the scrambling / unscrambling algorithm. In the latter case, it could be envisaged not to inhibit by the signal 11 the management of the motor 40 and to transmit the

  ignition orders after passing through the control loop 4, 30, 6, 10.

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  When the unscrambled data is incorrect, the ignition management would be

  it is also incorrect and would in practice prevent the use of the car.

  In order to authorize the use of the car by holders of smart cards other than the holder of the card 30, provision may be made to access the computer 1 with the card 30 and then, from input means of human-machine data, such as a keyboard, linked to the computer 1, to store in the computer 1 the identity (32) of another card authorizing the use of the car. It can likewise be associated, with the identity of one or the other card, of data limiting the use of the car, for example in its duration or in its

  performance, for example by clamping the engine by means of processor 2.

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Claims (8)

  1. Computer for controlling the use of a motor vehicle comprising a set of operating members (40), including an engine, comprising, for managing the operation of at least one of the functional members (40), a processor (2), reading means (5) of portable control means (30) and means (10), of reception of at least one control datum of control means (30), to authorize the processor ( 2) to manage the organ in question (40), computer characterized in that the reception means (10) comprise descrambling means (13), the processor (2) is arranged to transmit at least one authorization data item (3) from its management of the member (40) to be managed to the control means (30) comprising scrambling means (31), the reception means (10) being arranged to unscramble (13) said data, beforehand scrambled (31) by the control means (30), and compare it (12) with the data (3) tran smise by means of   control (30) of the managed organ (40).   2. Computer according to claim 1, wherein said receiving means (10) are arranged (12) to compare said unscrambled data with the data transmitted by the processor (2) via a third party   (17) associated with the transmitted data (3).   3. Computer according to one of claims 1 and 2, wherein the means for   reception (10) comprise a generator (15) of pseudo-random sequences.   4. Computer according to one of claims I to 3, in which there are provided   means (21) for storing computer identification data to be compared with associated data (32) of the control means portable (30).   5. The computer as claimed in claim 1, in which the reception means (10) comprise an exclusive OR logic gate (12) for comparing the data (3) transmitted by the processor (2) and the unscrambled data. 9 2712711   6. Computer according to one of claims 3 to 5, wherein the generator   (15) of pseudo-random sequences comprises at the input an initialization circuit (16) arranged to force the outputs of the generator (15) into a condition determined.   7. Computer according to one of claims 1 to 6, which is arranged for   include, in the authorization data (3), an order data for said managed organ (40).   8. Computer according to one of claims 1 to 7, which is arranged to manage   an ignition member (40) of the engine.