EP0825316B2 - Method and system for writing an information key - Google Patents

Description

The invention relates to a method and a system for writing a key information transmitted from a central location to a remote location into a data carrier present there. In a preferred application, the data carrier is a key for a motor vehicle, wherein the key is to be issued by a dealer to the rightful owner of the motor vehicle, for example because this additionally requires a key or has lost a key originally received when buying the motor vehicle. It should be noted, however, that the method or system according to the invention is also suitable for other applications, for example keys for access control to specific rooms or areas. With the method or system according to the invention selected information can generally be stored in a data carrier in a secured manner.

In the EP 0 723 896 A2 A method for theft prevention of motor-driven motor vehicles is described, using an anti-theft system, with a controller containing the immobilizer function, at least one further theft-relevant system component and transmission lines for bidirectional communication between theft-relevant system components, an external central office, and a transmission unit, for data transmission between the theft-relevant system components and the central office. In order to ensure a safe and reliable commissioning of theft-relevant system components, it is provided that all theft-relevant system components of the anti-theft system before their initial startup stored each one characteristic of the respective system component identification number and non-readable from outside the system component, individual secret number in a nonvolatile data memory of the system component be provided. The central office registers the identification numbers and the secret numbers of the theft-relevant system components. The identification numbers used to identify the relevant theft-related system components are transmitted in clear text within the anti-theft system and between the anti-theft system and the central office. The non-clear-transmitted secret numbers of theft-relevant system components serve as communication keys for layptological protocols in the data transmission of theft-relevant system components within the anti-theft system or / and with the central office.

If a key information stored in a central location is to be written to a data carrier at a remote location, it must be prevented in conventional systems that the transmission of key information to the remote site can be intercepted without authorization, otherwise a fraudster who was listening unauthorized Enroll key information in their own media and thus, for example, unauthorized access to secure rooms or areas can procure. The other possibility of writing in the central location the key information in the disk and then send it to the remote location, is also unfavorable, since the disk can be stolen during transport.

The object of the invention is to specify a method for securely writing a key information in a data carrier, which is output at a location other than the location where the key information is generated or stored.

This object is achieved in that the key contains an ident information stored that is not readable from outside and thus secret, and that the key information encrypted in the central location with this identification information and the encrypted information to the disk at the issuing office is transmitted. In the data carrier, this encrypted key information is decrypted and stored again.

This method has the advantage that the data carriers can be sent free because they contain no key information, so that a possible thief can not use the disk. Unauthorized interception of transmitted encrypted key information is also of no use to a fraudster if he does not have a volume with the correct identity information to which he could enroll the encrypted key information.

It is important that each volume contains another, open Ident information that is readable. This makes it possible for each data carrier to contain an individual identification information that is different from other data carriers, in that the association between the further open identification information and the secret identification information is stored at the central location. With this measure, encrypted key information can only be decrypted correctly by one, the correct data medium.

To be able to organize the assignments of secret identification information and key information as well as the further, open identification information more easily, it is expedient if the identity information and the open ident information are written to the data carrier at a further point before the Data carrier is transported to the remote location. This additional location must then be coupled via a protected information transfer connection with the central location so that the same information can be written there. The further location can also be identical to the central location.

The key information to be transferred to the data carrier is uniquely assigned to at least one individual object, for example a motor vehicle. If a data carrier is to be assigned to such an individual object, the object information characterizing this object must be transmitted to the central location. In order to secure this transmission path as well, it is expedient to encrypt the object information before transmission to the central location with the further, open identification information.

For the encryption of data, a variety of different methods are known. In the method according to the invention can be used as a particularly simple encryption and decryption of the key information and the object information, an exclusive OR link with the Ident information. Since the identification information is secret, decryption without knowledge of the key information is not possible even with knowledge of the encryption method.

In addition or instead of the encryption by means of exclusive OR connection, an asymmetrical encryption method can be used for the encryption of the object information before the transmission from the remote location to the central location, wherein for the encryption of the object information or the encrypted object -Information the open key is used, while in the central office, the decryption is performed with the secret key of the asymmetric encryption method.

The invention further relates to a system for writing a key information transmitted from a central location to a remote location into a data carrier present there, as well as a data carrier and a terminal for use in such a system.

An embodiment of the invention will be explained in more detail with reference to the drawing. Therein, a central location 20 contains two memories 21 and 25. The memory 21 contains two groups 22 and 23 of memory locations, which are each assigned in pairs to one another. By calling a memory location of the group 23 with a specific information, namely an open Ident information of a particular disk for data carriers with individual different ident information or specifying a volume group for data carriers with groups of identical Ident information, this is associated Ident information the assigned memory space of the group 22 read out.

Likewise, memory 25 in this example includes three groups 26, 27 and 28 of memory locations. Object information is stored in the memory locations of the group 26, and each of these memory locations is assigned a specific memory location of the group 27, which contains a key information associated with this object. Furthermore, each memory location of the group 26 is preferably assigned a plurality of memory locations of the group 28 which contain a number of identification numbers. Their meaning will be explained later.

At a further point there is a data carrier 10. In practice, of course, many data carriers are present, which are constructed equal to each other and for which the data carrier 10 indicated here is representative. This data carrier 10 contains a processing unit 11 and four memory locations 12 to 15. The memory location 12 is used to store identification information that can only be processed internally in the data carrier 10 and is never output to the outside. The memory location 13 contains a further identification information which identifies the individual data carrier and which can be read out to the outside. These two pieces of information are preferably provided by the central location 20, where these two pieces of information are written in two mutually associated memory locations of the groups 22 and 23 of the memory 21, and this information will also be at the other location where the volume 10 is initially located , inscribed in the memory slots 12 and 13. The further location may be identical to the central station 20.

This writing into memory locations 12 and 13 takes place for a plurality of data carriers, and these data carriers are then transported via a transport path 19 to a remote location. This transport path runs at least partially over an unprotected area, which is indicated by the dot-dash line 39. During this part of the transport path, the media may possibly be stolen. However, such a theft can not cause any significant damage since the data carriers do not yet contain any key information and thus can not be used on any object.

If a key information for a particular object is to be written to the remote location in a data carrier, namely in the volume 10 ', which is shown somewhat more in the figure, this data carrier 10' is connected to a terminal 40. As a result, the open identification information contained therein is read from the memory location 13 'and supplied via the connection 43 to the terminal 40. Furthermore, object information is input via an input 41, for example via a keyboard. These two pieces of information are fed to an encryption device, which here consists of two parts 42 and 44.

The part 42 of the encryption device is embodied here as an exclusive OR connection. The linked information, which thus represents the object information encrypted with the open identification information, is supplied to a part 44 which performs an asymmetrical encryption, for example according to the RSA method, with a fixed key, which is indicated here as being supplied via an input 45. This key does not need to be secret, because with its help a decryption is not possible.

The additional encryption with the open Ident information brings a significant improvement in security. Assuming that the data transmitted by a workshop, namely encrypted object information and open identification information, is being intercepted by a fraudster who himself possesses pre-programmed keys. If this fraudster transmits the same encrypted object information, but with the key's ID open, he would get the key information for the object encrypted with the secret ID information of his key without the encryption with the open identity information and thus decrypted correctly in the key so that a valid key for the object is unlawfully obtained. Due to the additional encryption with the open identity information, the encrypted object information transmitted by the fraudster is not properly decrypted at the central location, so that the desired key information is not read from the memory 25. However, if the fraudster also transmits the likewise intercepted open identity information, he merely receives key information which is not encrypted with the secret identity information stored in his key and which therefore can not be decrypted. It is therefore not possible, by eavesdropping on an authorized transfer for an object to obtain data with which a key for the same object can be generated without justification.

The encrypted information delivered by the part 44 via the line 47 is now supplied via the line 43 to the central point 20 as well as the open identification information. This transmission can take place via an unsecured way, since the encrypted information on the line 47 can not be decrypted without knowledge of the secret key of the asymmetrical encryption and the open identity information contains no direct indication of the key information required in the data carrier.

In the central location 20, the encrypted information on the line 47 is supplied to a decryption device comprising the parts 32 and 34. In part 34, a decryption of the transmitted information via the line 47 information is performed, with the help of a secret key, which is indicated here supplied via an input 35. At the output 37 of the part 34 of the decryption device is then the same information as at the output of the exclusive OR operation 42 in the terminal 40. However, this is not yet the input 41 of the terminal 40 supplied object information. Therefore, the line 37 leads to an exclusive-OR operation 32, which receives the open identification information via the line 43 at a further input. At the output 33 of the exclusive-OR operation 32 is now the decrypted object information with which the memory 25 is driven. In this case, the memory location containing this object information is selected in the group 26, and the key information is read from the associated memory location of the group 27. Furthermore, with the help of the open identification information on the line 43, the memory 21 is driven by looking up the memory location of the group 23 containing this identification information and the associated memory space of the group 22 containing the secret identification information. is read out.

The information read from the memory 21 and the memory 25 is supplied to an encryption device 30, which is also designed here as an exclusive OR connection. The information appearing at the output 31 is now transmitted to the remote location, the transmission path need not be secure, since the decrypted key information from the information on the line 31 can only be obtained with the help of the correct secret ident information, but in the disk is stored hidden and is not transmitted directly.

In the present example, an identification number is also read from the memory 25 from an assigned memory location of the group 28 and transmitted via the line 38 to the remote location, whereby an unsecured path can also be used.

In the remote location, the information on the line 31 and the line 38 via the terminal 40 to the disk 10 'is supplied. The identification number on the line 38 is written in the data carrier 10 'directly in the memory location 15', while the encrypted key information is supplied on the line 31 to a decryption device 17, which receives the secret ident information from the memory location 12 'at another input. This decryption device is again executed as exclusive-OR operation and thus outputs at the output the decrypted key information which is written into the memory location 14 '. Thus, the volume 10 'now contains all the information necessary for its use in a particular object, for example in a motor vehicle, without the crucial key information can be determined in the transmission in an unauthorized manner.

The identification number in memory location 15 'is not absolutely necessary for the described method and serves, if the data carrier is a key for a motor vehicle, that the vehicle is first checked via this identification number, whether it is a permissible key, before Help the key information is checked if it is a legitimate key. Namely, if a number of start attempts have been made with an unauthorized key, ie with a wrong key information, all will Functions of the motor vehicle permanently blocked, the blocking can be canceled only with a specific, secret procedure. By identifying number is thus prevented that with a wrong key, for example, belongs to another motor vehicle and thus of course contains a different key information can be performed as valid failed attempts.

Suitably, each authorized key for a motor vehicle contains a different identification number, and therefore a number of identification numbers are stored in the memory 25 for each object information and also in the associated object.

It is clear that the encryption in the terminal 40 by means of the parts 42 and 44 and the corresponding decoding in the central location can also be carried out in other ways than described. It is important that the information on the line 47 is encrypted in a way that does not allow decryption only by transmitted information.

Claims (10)

1. A method of writing key information transmitted securely from a central station to a remote station into a data carrier available at said remote station, which after being written into is unambiguously assigned to a selected one of a plurality of objects through the key information and which stores identification information that is not externally readable, as well as further public identification information that is readable, which types of identification information are stored, assigned to one another, also in the central station, wherein first object information characteristic of the individual object as well as the further public identification information is transmitted to the central station,
   where the key information which has been stored for the object information is read out and encrypted with the identification information stored for the transmitted further public identification information and the encrypted key information is transmitted to the data carrier and is decrypted there with the identification information stored thereon and the decrypted key information is stored,
   where at a further data carrier location, which is coupled to the central station via a secure information transmission link, the identification information and the further, public identification information is written prior to the transport from the data carrier to the remote station and this identification information is also stored at the central station,
   and where the object information is encrypted with the further public identification information prior to the transmission to the central station.
2. A method as claimed in claim 1, wherein the encryption and decryption of the key information and of the object information is effected by means of an Exclusive-Or combination with the further open identification information.
3. A method as claimed in claim 1, wherein prior to transmission the encrypted object information is additionally encrypted with the public key associated with an asymmetrical encryption method and is decrypted in the central station by means of the secret key of the encryption method.
4. A system for writing key information transmitted securely from a central station to a remote station into a data carrier available at said remote station, which key information after being written is unambiguously assigned to a selected one of a plurality of objects, wherein the central station comprises a first memory which stores at least identification information of one type and associated identification information of a further type, as well as object information characteristic of the object for each of the plurality of objects and stores the key information associated with the object, and an encryption device for encrypting key information read from the first memory with the identification information and a transmission device for transmitting the encrypted key information to the remote station, and wherein the data carrier comprises a second memory which contains a first storage area for identification information of one type, a second storage area for key information and a third storage area for identification information of a further type characteristic of the data carrier, and a decryption device which is connected to an information input of the data carrier and to the first storage area in order to supply decrypted key information upon reception of encrypted key information and to write the decrypted key information into the second storage area, wherein the remote station includes a terminal adapted to be coupled to the data carrier to initiate the read-out of the further identification information and to transmit this further identification information to the central station and to receive the encrypted key information subsequently transmitted from the central station and transmit it to the data carrier, and wherein the terminal includes an encryption device for encrypting written object information with the further identification information and transmit it to the central station, and the central station includes a decryption device for decrypting the received encrypted object information by means of the equally transmitted further identification information and for controlling the first memory and reading out the associated key information by means of the decrypted object information.
5. A system as claimed in claim 4, wherein the encryption device in the central station and the decryption device in the data carrier are constructed as Exclusive-Or logic elements.
6. A system as claimed in claim 4 or 5, wherein the encryption device in the terminal is adapted to encrypt the encrypted object information additionally with the public key of an asymmetrical encryption and to transmit it to the central station, and the decryption device in the central station is adapted to decrypt the received, additionally encrypted object information with the secret key of the asymmetrical encryption and with the likewise received further identification information and to supply the decrypted object information to the first memory.
7. A data carrier for use in a system as claimed in any one of the claims 4 to 6, comprising a decryption device and a memory having a first storage area for storing identification information and a second storage area for storing key information, the decryption device being coupled to the first storage area to decrypt received encrypted key information by means of the identification information read from the first storage area and to write the decrypted key information into the second storage area while read-out of the identification information from the data carrier is inhibited, wherein the decryption device is constructed as an Exclusive-Or logic element.
8. A data carrier as claimed in claim 7, wherein the memory comprises a third storage area for storing further identification information, and the memory is controllable from outside the data carrier in order to issue the further identification information from the memory.
9. A terminal for use in a system as claimed in any one of the claims 4 to 6, comprising a coupling device for a data carrier, a transmission device for information, an input device for the entry of information, and an encryption device having two inputs which are connected to the input device and the coupling device, and an output connected to the transmission device, for encrypting object information, which has been entered via the input device, with identification information applied via the coupling device, and for supplying the encrypted object information to the transmission device.
10. A terminal as claimed in claim 9, wherein the encryption device is adapted to encrypt the encrypted object information additionally with the public key of an asymmetrical encryption and to supply only the additionally encrypted object information to the transmission device.

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