WO2008113669A1

WO2008113669A1 - Device, system, configuration method and configuration device

Info

Publication number: WO2008113669A1
Application number: PCT/EP2008/052470
Authority: WO
Inventors: Rainer Falk; Florian Kohlmayer
Original assignee: Siemens Aktiengesellschaft
Priority date: 2007-03-16
Filing date: 2008-02-29
Publication date: 2008-09-25
Also published as: DE102007012751A1; DE102007012751B4

Abstract

A device comprises a key memory (MEM) in which at least one predetermined key subset (Kxn) associated with the device is stored. The at least one predetermined key subset (Kxn) comprises at least two secret keys. The at least one predetermined key subset (Kxn) represents a respective unambiguous subset of at least one predetermined key set (Kx) which is predetermined for a plurality of device. The device comprises a predetermined identifier (ID) that is representative of which keys of the at least one predetermined key set (Kx) are contained in the at least one predetermined key subset (Kxn).

Description

description

Device, system, configuration method and configuration device

The invention relates to a device and a system with at least two of these devices. Furthermore, the invention relates to a configuration method and a configuration device for configuring the device.

In a sensor network, messages are sent from a respective sender node of the sensor network to a respective destination node of the sensor network. If necessary Müs ^¬ sen messages each have one or more intermediate nodes are transmitted until the messages reach their respective destination node. Such sensor networks are generally operated uncontrollably, so that attackers very easily have the opportunity to acquire one or more of the nodes of the sensor network and / or listen to news or to false ones. In particular, an attacker can send it as one of the nodes of the sensor network out ^¬ ben and fake messages with its identity.

The object of the invention is to provide an apparatus and a Sys tem ^¬, in or at which a reliable authenticating a sender of data is possible. Further, the object of the invention to provide a Configurati ^¬ onsverfahren and a configuration device to the configurations of the device to provide centering, which makes simple authenticated or the device.

The object is achieved by the features of the independent claims. Advantageous developments of the invention are characterized in the subclaims.

According to a first aspect, the invention is characterized by a device with a key memory in which at least one predetermined key part quantity assigned to the device is stored. The at least one ^{predetermined subset of clauses} comprises at least two secret keys. Each of the at least one predefined set of keys represents a unique subset of at least one predetermined set of keys, which is predetermined jointly for a plurality of devices. The apparatus includes a predetermined identifier that is representative of that key of the at least one predetermined Schlusselmenge in the at least one predetermined Schlusselteilmenge are contained ^¬ th.

The predetermined identifier is formed as a function of the keys contained or not contained in the at least one predetermined key subset. The at least one predefined set of key parts is uniquely predetermined, that is, the predetermined key subset of different devices are different. Thus, the predetermined identifier is also clearly specified. This has the advantage that the predetermined identifier of the device can be easily used to the device clearly identi ^¬ fied, as compared to other devices. Furthermore, it can be determined very easily based on the given identifier, which key the device has, without having to examine the contents of the key memory. This information can be used to authenticate the device or a message sent by it.

In an advantageous embodiment, the predetermined identifier comprises a sequence of predetermined symbols. This sequence is at least as long as symbols are contained in the key set containing the largest number of secret keys. At least two different predefined symbols are provided. Each Posi ^¬ tion in the sequence of predetermined symbols, a respective key associated with each selmengen at least one of the predetermined Schlus-. By the given symbol At the respective position, the presence or absence of the key assigned to the respective position is coded in the at least one predetermined key subset. The advantage is that such a given identifier is simple and can be made compact, that is, requires little storage space.

In this context it is advantageous if a specified ^differently bene Schlusselteilmenge and a first and a second symbol are provided. The first symbol at each position encoding the presence and the second symbol at the time jewei ^¬ position encoding the absence of the respective position of the associated key in a predetermined Schlusselteilmenge. The advantage is that this is especially easy.

Alternatively, it is advantageous in this context if at least two predetermined key sets are predetermined and each of the at least two predetermined key sets is assigned a different symbol. The respective symbol at each position encoding the presence or absence of the associated position of the respective key in the labeled in by the respective symbol ^¬ recorded predetermined Schlusselteilmenge. That is, the symbol at the respective position indicates from which of the predetermined key sets the key is derived, which is assigned to the respective position. The advantage is that there ^¬ by both the presence and the absence of the respective position of the associated key switch is repeatedly verifiable. This allows a particularly reliable authentication.

In a further advantageous embodiment, the sequence of predetermined symbols is a sequence of bits. The default symbols are the binary values one and zero. The advantage is that the predetermined identifier can be designed to be particularly compact and is particularly easy to process. In a further advantageous embodiment, the device is designed to determine in each case at least one test value with at least two of the keys of the at least one predetermined key subset depending on the data to be sent. The device is also designed for

Sending messages via a network, the data specified identifier and the Prufwerte determined umfas ^¬ sen. This has the advantage that by the binding of pre ^¬ given identifier to the information contained in the at least one predetermined key Schlusselteilmenge a recipient of the

Message simply the authenticity of the message and Ab ^¬ sender of the message, that is, the device can check and so can detect manipulation. This applies in particular to the case in which a test value is determined for each key of the at least one predetermined key subset of the device and attached to the message.

In a further advantageous embodiment the apparatus is adapted for receiving messages from a network, the data, the predetermined identifier of a sender of the respective message, at least two Prufwerte and ^¬ appropriate, include gege each case a final diesel detection for each of the at least two Prufwerte. Furthermore, the device is designed to check each message depending on the respectively received predetermined identifier of the sender of the respective message and a respective number and order of the received at least two test values and / or the possibly received key identifications of the at least two test values. When checking the respective message, it is checked whether, for each of the at least two test values in the received predefined identifier of the sender, it is indicated that the respectively associated key is contained in the at least one key-part set assigned to the sender. This has the advantage that the authenticity of the sender of the message and / or the message is easily verifiable. Via the respective number and order of receive ^¬ NEN least two Prufwerte a ^¬ times is determined, for example, by means of which key of the respective test value was supposedly determined. Alternatively or additionally, however, this can also be determined by evaluating the respective received key identifier, if such is attached to the respective test value. The device can thereby check each message very easily depending on the respectively received given identifier of the sender.

In a further advantageous embodiment the apparatus is adapted for receiving messages from a network, the data, the predetermined identifier of a sender of the respective message, at least two Prufwerte and ^¬ appropriate, include gege each case a final diesel detection for each of the at least two Prufwerte. The device is further configured to check each message depending on the respectively received predetermined identifier of the sender of the respective message and a respective number and order of the received at least two Prufwerte and / or optionally received key identifications of the at least two Prufwerte, which key for determining the each test value was allegedly used. Furthermore, the device is designed to check the respective test value if the key supposedly used for determining the respective test value is stored in the key memory, depending on this stored key. This has the advantage that unauthorized Manipula ^¬ tions of the message or data are simply determined. Via the respective number and order of receive ^¬ NEN least two Prufwerte a ^¬ times is determined, for example, one was to which key of the respective Pruf- determined value supposedly. Alternatively or additionally, however, this can also be determined by evaluating the respective received key identifier, if such is attached to the respective test value. As a result, the device can very easily check each message depending on the respectively received given identifier of the sender.

In this context, it is advantageous if the device is designed to add a test documentation to the received message indicating for which keys of the at least one predetermined key quantity the checking of the associated check value of the received message was successfully performed. Furthermore, it is advantageous if the device is designed to send the message over the network. The advantage is that be ^¬ already checked Prufwerte where appropriate, need not be checked again on ^¬, preferably those Prufwerte can be checked the message that have not yet been berpruft u. As a result, a available computing capacity of the device for checking the test values can be used particularly efficiently.

In this connection it is further advantageous if the device is designed for determining each of at least one Prufwerts with at least one of the key min ^¬ least a predetermined Schlusselteilmenge dependent on the Prufdokumentation. Furthermore, it is advantageous if the device is designed to add the at least one test value to the message. This has the advantage that an unauthorized manipulation of the test documentation is easily ascertainable by checking this at least one test value.

In a further advantageous embodiment the apparatus is adapted for receiving messages from a network, the data, the predetermined identifier of a sender of the respective message, at least two and Prufwerte min ^¬ least comprise a Prufdokumentation. Furthermore, the device is designed to send the respective message to a next device in the network, wherein the next device is selected depending on its predetermined identifier and the received test documentation. The advantage is that messages can thereby be sent very simply, for example, to the next device in the network which has the keys required for checking those test values which, according to the test documentation, have not yet been checked. In the- formation, over which key the next device has, is easily recognizable by its given identifier. The path of the respective message through the network can thereby be automatically selected so that as many as possible of the test values of the respective message are checked. The authenticity of the sender of the message or the message can be determined so particularly reliable.

In a further advantageous embodiment, the device is designed as a node for a sensor network, which is uniquely identifiable in the sensor network by its predetermined identifier. The advantage is that the bone ^¬ th is clearly identifiable in the sensor network and the authenticity of the node and sent by this news is easy to check.

According to a second aspect, the invention is characterized by a configuration method and a corresponding configuration device for configuring a device that comprises a key memory. At least one specified ^differently bene Schlusselteilmenge for the apparatus is determined and the device assigned to and stored in the Schlusselspeicher. The at least one predetermined Schlusselteil ^¬ amount of at least two secret keys and represen- advantage respective unique subset of at least one front ^¬ given Schlusselmenge which is predetermined jointly for a plurality of devices. A predetermined identifier is determined for the device and the device associated with which is re presentative ^¬ as to which key of a predetermined Schlusselmenge in the one specified ^differently surrounded Schlusselteilmenge are included at least at least.

The predetermined identifier is formed as a function of the keys contained or not contained in the at least one predetermined key subset and predefined for the device. The at least one predefined set of key parts is specified unambiguously, that is to say the predetermined key subset quantities of different devices are subordinate to one another. different. Thus, the predetermined identifier is also uniquely specified ^¬ . This has the advantage that the predefined identifier of the device can be used very simply to uniquely identify the device, for example compared to other devices. Furthermore, based on the given identifier, it is very easy to determine which keys the device has, without having to examine the ^{contents of} the key ^memory . This in ^¬ formation can be used to authenticate the device or despatched by this news.

The configuration method and the configuration device may also be designed to configure devices according to one of the advantageous embodiments of the first aspect.

According to a third aspect, the invention is characterized by a system comprising at least two of the devices according to the first aspect, which are coupled together to form a network.

Exemplary embodiments of the invention are explained below with reference to the schematic drawings. Show it:

FIG. 1 shows an overview of an assignment of keys from predefined sets of keys to predetermined key shares and to nodes,

FIG. 2 shows a formation scheme for a given identifier of a respective node,

FIG. 3 shows a first embodiment of a message,

FIG. 4 shows a second embodiment of a message,

FIG. 5 is a flowchart of a program for sending a message; FIG. 6 is a flow chart of a program for receiving,

Processing and possibly forwarding a message,

Figure 7 is a flow chart of a program for configuring a node and

FIG. 8 shows a network formed by a plurality of nodes or

Sensor network.

Elements of the same construction or function are provided with the same reference numerals across the figures.

At least one predefined set of keys Kx with a large number of secret keys is specified in common for several devices (FIG. 1). The devices may also be referred to as node N. For example, the devices are designed as nodes N for a network and in particular as sensor nodes for a sensor network. Examples of playing the respective sensor node comprises at least egg ^¬ NEN sensor. Preferably, the nodes N are each designed to form an ad hoc network or an ad hoc sensor network with at least one further node N and to exchange data DAT with one another. The data DAT are, for example, sensor data which were acquired by means of the at least one sensor of the respective sensor node or were determined as a function of such detected sensor data.

Each node N is assigned at least one predetermined set of key parts Kxn. The respective at least one specified ^differently bene Schlusselteilmenge Kxn representing a unique subset of each of the at least one predetermined Schlusselmenge Kx. Each node N comprises a key memory MEM. The keys of the at least one predetermined key subset Kxn assigned to the respective node N are stored in its key memory MEM.

For example, a first node is Nl, a second node N2 and a third node N3 provided. Each of these nodes has in each case the key memory MEM. The first node Nl is a first predetermined set of key parts KIl ^¬ ordered, which is a unique subset of a first predetermined key set Kl. According to a second predetermined Schlusselteilmenge K12 and the third node associated with a third predetermined amount Schlusselteil ^¬ K13 N3 which are each a unique subset of the first predetermined Schlusselmenge Kl to the second node N2. A definite subset is to be understood as meaning that the predetermined key subset Kxn, that is to say, for example, the first, second and third predefined key subset KI1, K12, K13, differ from each other by at least one key.

Further, a second predetermined Schlusselmenge KO can be determined, from which a fourth predetermined Schlussel ^¬ subset glycol, a fifth and a sixth predetermined Schlusselteilmenge K02 predetermined Schlusselteilmenge K03 are formed as unambiguous subsets of the second predetermined Schlusselmenge KO. It may further be provided that the fourth predetermined set of key parts KOl the first node Nl, the fifth predetermined Schlussteilteilmenge K02 the second node N2 and the sixth predetermined Schlusselteilmenge K03 the third node N3 is assigned and the keys of the respective predetermined Schlusselteilmenge Kxn in the respective key memory MEM are stored.

There may also be more than three nodes N provided. Correspondingly, more predetermined key subset quantities can also be used

Kxn be provided. Furthermore, more than two predefined key sets Kx can also be specified in common for the nodes N.

The keys in the at least one predetermined quantitative Schlussel ^¬ Kx, so, for example, in the first predetermined Schlusselmenge Kl and the second predetermined amount Schlussel ^¬ KO, in particular secret key. The keys are usable in particular for cryptographic methods, for example for symmetric encryption or for determining test values P. Preferably, the keys assigned to the respective nodes N are stored securely and protected against manipulation in the respective key memory MEM.

Each node N has a predetermined identifier ID. In ^¬ play, the first node Nl has a first predetermined identification IDl, the second node N2, a second predetermined identification ID2 and the third node N3 a third predetermined identifier ID3 on. The respective predetermined identifier ID is unique for each ^¬ weils the corresponding node N. This is because ^¬ achieved by that the respective predetermined identifier ID is formed from ^¬ hangig of the keys, the at least one uniquely predetermined Schlusselteilmenge Kxn are contained in, which is assigned to the respective node N.

The respective predetermined identifier ID preferably comprises a sequence of predetermined symbols for this purpose. For example, the predetermined symbols one and zero are provided. The keys in the respective predefined set of keys Kx are, for example, numbered consecutively or have a key identification. Depending on the respective number or key identifier, each key is assigned to a position i in the sequence of the predefined symbols. For example, the equivalent

Number of the respective key in the respective predetermined key set Kx of the respective position i in the sequence of the given symbols. The respective final diesel detection, for example, represents the particular number or position i or allows in a different way to a unique ^¬ order of each key to one of the positions i.

In FIG. 2, the basic education scheme is shown by way of example for the first predetermined identifier ID1 of the first node N1. In a first embodiment, the first node Nl is only the first predetermined Schlusselteilmenge Kil supplied ^¬ assigns, but not the fourth predetermined Schlusselteilmen ^¬ ge col. For example, it is provided, the predetermined symbol To use one in the sequence of the given symbols in order to indicate that the key of the first predetermined key quantity K associated with the respective position i is contained in the first predetermined key subset KI1 assigned to the first node N1 and thus also stored in its key memory MEM is. For example, it is further provided that the predetermined symbol zero at the respective position i is used in the sequence of the predefined symbols in order to indicate that the key assigned to the respective position i is the first predetermined one

Schlusselmenge Kl is not included in the first node Nl zugeord ^¬ Neten first predetermined Schlusselteilmenge KIL and thus is not stored in the Schlusselspeicher MEM. Characterized is encoded in the first predetermined identification IDl, which keys in said first predetermined FINAL ^¬ selmenge Kl are included in the first predetermined Schlusselteilmenge KIL and stored in the Schlusselspeicher MEM of the first node Nl. The first predetermined identifier ID1 is therefore representative of the keys which are stored in the key memory MEM of the first node N1 and which are thus known to the first node N1 and are available to the latter, for example for determining and / or checking test values P.

In a second embodiment, the predetermined symbols are used to distinguish two or more than two predetermined key subset Kxn, which are assigned to the respective node N. For example, the predetermined symbol one according to the first embodiment is provided for identifying those keys of the first predetermined key subset KI1 that are known to the first node NI. Accordingly, the predetermined icon can be provided to zero, to indicate that the i associated with the respective position keys of the second predetermined Schlusselmenge KO is included in the fourth predetermined Schlusselteil ^¬ quantitative KOL and thus also in the Schlusselspei ^¬ cher MEM of the first node Nl stored is. In this example, therefore, for each position i of the sequence symbols store a key in the key memory MEM. By the respective predetermined symbol on the per ^¬ weiligen position is indicated i, which is the predetermined Schlusselmengen Kx of the respective associated key.

It may also be provided to provide other or further predetermined symbols. However, there are at least two pre-admit ^¬ ne symbols. Further, when more than two predetermined Schlusselmengen Kx any of these predetermined Schlusselmengen Kx is preferably at least arranged a predetermined symbol to ^¬.

Preferably, the sequence of predefined symbols is a sequence of binary bits. The symbols are given preference ^¬, as binary values one and formed zero. However, the pre ^¬ given symbols and the sequence of predetermined symbols can also be designed differently.

Furthermore, each of the predetermined key subset quantities Kxn preferably has the same number of keys among each other, so that each node N has the same number of keys in its respective key memory MEM. The predetermined key sets Kx preferably also have the same number of keys each other. The

However, the number of keys can also be specified differently.

The respective predetermined identifier ID of the respective node N is provided for a unique identification of the jewei ^¬ time node N in the network that is formed from at least two and preferably at least four nodes N. The nodes N are designed to send messages MSG to other nodes N and / or to receive such messages MSG.

FIG. 3 shows an example of the structure of such a message MSG. The message MSG comprises the predetermined identifier ID of a sender of the message MSG. The one node N, to be the ex ^¬ sender of a message MSG is also referred to as a sender node Na. It may also be advantageous, given the prior ^¬ identifier ID of a desired consignee of the post-Judges MSG in each message MSG to code. Derje ^¬ Nige node N, which is the desired recipient of a message MSG is also referred to as a destination node Nz. Furthermore, the message MSG comprises the data DAT to be transmitted, which may also be referred to as user data and which includes, for example, sensor data. However, the data DAT can also be, for example, administrative data or control data for managing or controlling the network or Sen ^¬ sornetzwerks. For example, the data DAT may include infor mation on ^¬ other nodes N by which the jewei- leaf node N communicates directly or indirectly. Depending on this information, it is possible, for example, to forward messages MSG to a respective next node nN. Such information may also be referred to as routing information.

Starting from the sender node Na of the respective message MSG, the next node nN is either the destination node Nz if the sender node Na is directly connected to the destination node Nz or an intermediate node Ni if the sender node Na is only indirectly, ie via at least one intermediate node Ni, associated with the destination node Nz. Accordingly, the next node nN, starting from one of the intermediate nodes Ni, can be the destination node Nz or else a further intermediate node Ni.

Furthermore, the message MSG comprises at least two test values P which were respectively determined as a function of the data DAT and of one of the keys assigned to the sender node Na in accordance with the at least one predetermined key subset Kxn assigned to it. For example, the test values P are determined according to a message authentication code, which can also be referred to as a message authentication code, or MAC for short. The test values P can but also be determined differently. ^¬ the sender node Na is preferably configured to determine for each stored in the MEM Schlusselspeicher a key Prufwert P and be attached to the message MSG. However, it can also be provided to determine the test value P for only a few of these keys and to attach them to the message MSG.

The message MSG may also, in Figure 3 is not Darge ^¬ presented include information such as a sequence number payers. Furthermore, it can be provided that the respective

Prufwert P not only dependent on the data DAT to determine, but also depending on, for example, the sequence number payer and / or a source and / or destination address, that is, for example, depending on the given identifier ID of the sender and / or the desired Receiver of the message MSG.

Optionally, the respective message MSG can be the Zielkno ^¬ th Nz not directly sent by the sender node Na, i.e., the message MSG must if necessary be routed via one or more intermediate nodes Ni, each having a node N of the network Bezie ^¬ hung example sensor network form. Preferably, the respective node N, which is used for the message MSG as an intermediate node Ni ^¬ or representing the destination node Nz checks the message MSG to possible tampering, and in particular ^¬ sondere authenticity. The respective nodes N and in particular ^¬ sondere intermediate node Ni is therefore preferred to ausgebil ^¬ det to check whether the Prufwerte P that have been received with the message MSG, also from the sender node Na ermit- telt could be, that is, whether the sender node Well according to its given identification ID also has the necessary keys. Furthermore, it can be provided to check a number of the test values P in the message MSG, in particular if it is provided that a test value P of the respective message MSG is added for each key known to the sender node Na.

Preferably, the respective node N is one of the intermediate nodes. node Ni or the destination node Nz, trained to check the correctness of those test values P, for which this has itself the key required in each case. If the key memory MEM of the respective intermediate node Ni or of the destination node Nz thus contains keys which also have the sender node Na and if the message MSG has test values P determined by one of these keys, then the respective intermediate node is Ni or destination node Nz able to check with its own key the respective check value P as a function of the data DAT and possibly further information of the message MSG. For checking, the respective intermediate node Ni or the destination node Nz determines, for example, the associated check value P new and compares this with the check value P in the message MSG. If these Prufwerte P not mitein ^¬ other uberein, the message MSG has been altered or tampered with by the sender node Na. Preferably, such a message MSG is discarded and possibly not sent to another intermediate node or to the destination node Nz. However, if the test values P are identical, then the respective intermediate node Ni preferably adds a test documentation PD to the message MSG, in which it is documented for which keys the respective test value P was successfully checked. FIG. 4 shows, by way of example, the structure of such a message MSG.

For example, the check documentation PD is embodied as a sequence of binary values, in which, for example, a binary one at the respective position i indicates that the check value P in the message MSG which was determined with the key assigned to the position i according to the predetermined identifier ID, was successfully checked. Accordingly, a binary zero indicates that a check could not be carried out, for example because the respective intermediate node Ni does not have the key assigned to the respective position i. However, the test documentation PD can also be formed differently. Furthermore, provision may also be made for not determining the test documentation PD and the Add MSG message.

The respective intermediate node Ni, the hinzufugt the message MSG the Prufdokumentation PD, also trained det to determine at least one Prufwert P dependent on the Prufdoku ^¬ mentation PD and add the message MSG is preferred. As a result, the test documentation PD can also be checked for unauthorized manipulations by other intermediate nodes Ni or by the destination node Nz. Preferably, for all keys known to the respective intermediate node Ni, test values P are determined as a function of the test documentation PD and added to the message MSG. However, it may also be provided to determine only a Prufwert P for some of the keys and add the message MSG. The respective intermediate node Ni is preferably designed to also add its predefined identifier ID to the message MSG. The checking of the test values P, which were determined as a function of the test documentation PD, is possible in accordance with the checking of the test values P, which were determined as a function of the data DAT. With regard to the check documentation PD, however, the respective intermediate node Ni represents the sender node Na, which has added the check documentation PD and the associated at least one check value P to the message MSG.

FIG. 5 shows a flow diagram of a program for sending the data DAT. The program is preferably executed by the sender node Na. The program starts in a step Sl. In a step S2, the data DAT ermit ^¬ telt and possibly prepared suitable for shipping. In a step S3, test values P for at least two and preferably for all keys stored in the key memory MEM are determined as a function of the data DAT. In a step S4, the message MSG is assembled. The message MSG comprises the predetermined identifier ID of the sender derknotens Na, data DAT, and the ermit ^¬ telten in the step S3 Prufwerte P. Further, the message MSG may also include the predetermined identification ID of the target node Nz or other destination address and possibly other information , to the Example, the sequence number payer include. The test values P determined in step S3 can also be formed as a function of the given identifier ID of the sender node Na and / or the destination node Nz and / or the other destination address and / or the further information. The message MSG is sent in step S4 to the next node nN, thus possibly to one of the intermediate nodes Ni or to the destination node Nz. The program ends in step S5.

Figure 6 shows a flow diagram of a program for receiving and checking messages MSG. The program is executed in particular by an intermediate node Ni between the sender node Na and the destination node Nz. However, the program can also be executed by the destination node Nz. The program starts in a step S6. In a step S7, the message MSG is received. The message MSG comprises the predetermined identifier ID of the sender node Na, the data DAT, the Prufwerte P of the sending node Na and optionally the test documentation PD and optionally further comprising a Prufwert P or more Prufwerte P of the intermediate node Ni, the message MSG previously ge ^¬ has checked. The Prufwert P or P Prufwerte the intermediate ^¬ node Ni are particularly dependent on the Prufdokumenta- tion PD determined. Optionally, several functions are Prüfdokumenta- PD and associated Prufwerte P of the message MSG beige ^¬ adds, for example, if the message MSG has already been tested by two or more than two intermediate nodes Ni.

In a step S8, the test values P are checked. The U can Aged people refer to it that the respective nodes N, so sender node Na or intermediate node Ni, the keys are known according to their respective preset identification ID and for which the node N Prufwerte P of the post ^¬ directing MSG have Added. For example, each check value P is provided with a key ID in the message MSG. For example, comprises or represents the final voltage cloves ^¬ i the position of the key in the respective Schlus- selmenge Kx and according to given in the respective Identifier ID. The checking then comprises, for example, checking the predetermined identifier ID of the respective node N and the respective key identifier which is associated with the respective check value P determined by the respective node N.

However, the checking may alternatively or additionally also be dependent on a number and / or sequence of the test values P in the message and on the given identifier ID of the sender node Na or intermediate node Ni. In particular, when it is provided that each Prufwerte P for each of the respective node N known key determined and the message MSG to be Added, can be very a ^¬ repeatedly checked whether the respective nodes N are known for each according to its predetermined identifier ID code of the message MSG in each case a Prufwert P is attached. Furthermore, it can be provided to determine from the sequence of the test values P in the message MSG which position i and thus which key belong to the respective test value. Loading vorzugt Prufwerte the P key are logically arranged in the message MSG, so that it is very easy to be determined, which Prufwert P was determined which key in ascending or descending order according to the corresponding positi ons ^¬ i. The respective key identifier must then not be noted in the message MSG.

However, checking may alternatively or additionally also relate to that corresponding for keys that are known to the respective message MSG receiving node N, the Prufwerte P itself are checked, for example by New ^¬ calculate the respective Prufwerts P and comparing it with the Check value P in the message MSG.

If an error or discrepancy in the check is detected, then the program proceeds to a step S9. In the step S9, the message MSG is discarded before ^¬ preferably and the program be completed ^¬ in a step S. The mistake or the discrepancy can be a hint be that the message MSG has been changed without authorization or that the sender node Na or one of the possibly existing intermediate node Ni have falsified their predetermined identifier ID. An attacker who liked to pose for one of the nodes N, that is to say would like to assume its identity and for that purpose uses the given identifier ID, had to know all the keys known to this node N in order to be able to determine the correct test value P for this message and to attach it to the message MSG , Generally, however, the attacker does not know all these keys so that it at least can not determine all Prufwer ^¬ te P and these either omit or false needs. By checking therefore the sender node Na and / or the message MSG can be authenticated and an on ^¬ claws are detected.

However, if no error and no discrepancy is determined in step S8, then it is checked in a step S11 whether the message MSG is addressed to the node N currently executing the program, ie whether the node N currently being checked is the destination node Nz. If this condition is met, then the program is terminated in step S10. The data DAT can then be supplied to the optionally provided further processing in the destination node Nz.

If, however, the condition in step S11 is not fulfilled, that is to say the node N currently executing the program is not the destination node Nz but one of the intermediate nodes Ni, then the test documentation PD may be provided in a step S12 and, if appropriate, dependent thereon To determine test values P.

Furthermore, a step S13 may be provided in which the next node nN to which the message MSG is to be sent next is determined. Preferably, the next node nN is selected depending on its predetermined identifier ID and on the test documentation PD. If a plurality of next nodes nN are available for selection, then the message MSG is preferably forwarded to node N, which passes via as many as possible those keys have been included for the previously unverprufte Prufwerte P in the message MSG. For which key the verification has already been successfully carried out is documented in the test documentation PD. In this way it can be achieved that as many of the test values P that were added by the sender node Na to the message MSG are checked on their way to the destination node Nz. Unauthorized manipulations of the message MSG and in particular the predetermined identifier ID of the Abenderderknoten Na are so particularly reliable recognizable and the authenticity of the sender node Na and / or the message MSG can be determined particularly reliable.

In a step S14, the message MSG is collected and, optionally, the Added determined in step S12 Prufdo ^¬ mentation PD and associated Prufwerte P of the message MSG. Furthermore, the message MSG is forwarded to the next node nN. The program ends in step S10.

Disposes of the used the program export intermediate node Ni does not have the key necessary for checking at least one of Prufwerte P, then the post ^¬ directing MSG preferred in this regard ungepruft to the next node nN dispatched without first Prufdokumentation PD or Prufwerte P to identify and add ^¬ hinzuzu the message MSG.

Figure 7 shows a flow chart of a program for centering configurations of the respective node N. The program will ^¬ example as performed by the configuration device KV, which is shown in FIG. 1 The program starts in a step S15. In a step S16 a respective pre ^¬ added Schlusselteilmenge Kxn is determined as a unique subset of the predetermined Schlusselmenge Kx. In each case two or more than two predetermined key subset quantities Kxn can be determined from two or more than two predefined key sets Kx. In a step S17, the respective determined predetermined set of key parts Kxn assigned to the respective node N and stored in the key memory MEM. In a step S18, the predetermined identifier ID for each node N is determined dependent on the respective predetermined Schlusselmenge Kx and especially the numbering of the key in the respective predetermined Schlusselmenge Kx and dependent on the respective pre give ^¬ NEN Schlusselteilmenge Kxn. The determination of the respective given identifier ID takes place, for example, as the sequence of the predefined symbols, which is representative of which

Key of the at least one key set Kx are contained in the je ^¬ termigen predetermined key subset Kxn. In a step S19, the respective predetermined identifier ID is assigned to the respective node N and stored in this node. The method ends in a step S20.

FIG. 8 shows, by way of example, the network, and in particular the sensor network, which is formed from a plurality of nodes N. Such a network or sensor network of node N may also be referred to as a system. The nodes N are interconnected by dashed connections. Preferably, these compounds are designed as radio links. However, the connections can also be designed as cable connections. Furthermore, FIG. 8 shows by way of example a path of a message MSG from the sender ^code Na to the destination node Nz via three intermediate nodes Ni.

Preferably, all nodes N of the network or sensor network are of similar design. Furthermore, the nodes N are preferably designed so that these sender nodes can be Na, intermediate nodes Ni or destination nodes Nz for messages MSG that are sent in the network or sensor network. In this way, each node N is the other node of the network N or the transmitter sornetzwerks communicate with each ^¬ and exchange data DAT. By checking the messages MSG on their respective way from the sender node Na to the destination node Nz, messages MSG can be filtered by sending messages MSG which have failed. lerhaft or discrepancies in relation to the respective predetermined identifier ID, or the respective Prufwerte P have ^¬ be discarded. Thus, with a given probability which is dependent on a respective number of intermediate nodes Ni on the path of the respective message MSG, only those messages MSG reach their respective destination which have not been tampered with and are authentic with respect to the sender node Na. This predetermined International ^¬ probability increases with the number Ni of the intermediate nodes.

Claims

Claims:

1. Device with a key memory (MEM), in which at least one of the device associated predetermined final Kelselteil (Kxn) is stored, which comprises at least two ge ^¬ home key and each having a unique part ^¬ amount of at least one predetermined key set (Kx) rep ^¬ presented, which is common for a plurality of devices vorgege ^¬ ben, and the device comprises a predetermined identifier (ID), which is representative of which key of at least one predetermined Schlusselmenge (Kx) in the at least one predetermined key subset (Kxn) included are.

2. Device according to claim 1, wherein

the predetermined identifier (ID) comprises a sequence of predetermined symbols which is at least as long as there are keys in the predetermined key quantity (Kx) containing the largest number of secret keys,

- are seen ^¬ at least two different predetermined symbols provided,

- Each position (i) in the sequence of predetermined symbols is assigned a key in each case at least one of the predetermined key sets (Kx), and

the presence or absence of the key assigned to the respective position (i) is coded in the at least one predetermined set of key pieces (Kxn) by the respective given symbol at the respective position (i).

3. A device according to claim 2, wherein

- a predetermined set of key parts (Kxn) and a first and a second symbol are provided and - the first symbol at the respective position (i) the presence and the second symbol at the respective position (i) the absence of the key assigned to the respective position in FIG of a given set of key parts (Kxn) coded.

4. Apparatus according to claim 2, wherein

- at least two predetermined key sets (Kx) are given,

- the at least two predetermined key sets (Kx) is assigned a different symbol in each case, and

the respective symbol at the respective position encodes the presence or absence of the key associated with the respective position in the predefined set of key parts (Kxn) identified by the respective symbol.

5. Device according to one of claims 2 to 4, wherein - the sequence of predetermined symbols is a sequence of bits and

- the given symbols are the binary values one and zero.

6. Device according to one of the preceding claims, which is formed

- dependent for determining at least one Prufwerts (P) with at least two of the key of the at least one pre give ^¬ NEN Schlusselteilmenge (Kxn) to be mailed DA th (DAT), and

- for sending messages (MSG) via a network, comprising the data (DAT), the specified identifier (ID) and the ermit ^¬ telten test values (P).

7. Device according to one of the preceding claims, which is formed

- For receiving messages (MSG) from a network, the data (DAT), the predetermined identifier (ID) of a sender of the respective message (MSG), at least two Prufwerte (P) and optionally one key identifier for each of the at least two Prufwerte Include (P) and

for checking each message (MSG) depending on the respectively received given identifier (ID) of the sender of the respective message (MSG) and a respective number and order of the received at least two Prufwerte (P) and / or the optionally received key identifications of the at least two Prufwerte (P), which is checked in checking the respective message (MSG), whether for each the at least two Prufwerte (P) in the received specified ^differently surrounded identifier (ID) of the sender is indicated that each of the associated key in the at least one contained the Absen ^¬ the associated Schlusselteilmenge (Kxn).

8. Device according to one of the preceding claims, which is formed

- For receiving messages (MSG) from a network, the data (DAT), the predetermined identifier (ID) of a sender of the respective message (MSG), at least two Prufwerte (P) and optionally one key identifier for each of the at least two Prufwerte Include (P),

- For checking each message (MSG) depending on the respectively received predetermined identifier (ID) of the sender of the respective message (MSG) and a respective number and order of the received at least two Prufwerte (P) and / or the optionally received key identifications of the at least two Prufwerte (P), which key was supposedly used for determining the respective Prufwerts (P), and

- For checking the respective Prufwerts (P), when the for the determination of the respective Prufwerts (P) supposedly used key is stored in the key memory (MEM), depending on this stored key.

9. Apparatus according to claim 8, which is formed

for adding a check documentation (PD) to the received message (MSG) indicating for which keys of the at least one predetermined key set (Kx) the checking of the associated check value (P) of the received message was successfully performed, and

- to send the message (MSG) over the network.

10. Apparatus according to claim 9, which is formed

- dependent for determining at least one Prufwerts (P) with at least one of the keys of the at least one specified ^differently surrounded Schlusselteilmenge (Kxn) tation of the Prufdokumen- (PD), and

for adding the at least one test value (P) to the message (MSG).

11. Device according to one of the preceding claims, which is formed

for receiving messages (MSG) from a network comprising data (DAT), the given identifier (ID) of a sender of the respective message (MSG), at least two test values (P) and at least one test documentation (PD), and for sending the respective message (MSG) to a next Tier ^¬ te device in the network, the next device is selected dependent on their predetermined identifier (ID) and the received Prufdokumentation (PD).

12. Device according to one of the preceding claims, which is designed as a node (N) for a sensor network, which is uniquely identifiable in the sensor network by its predetermined identifier (ID).

13. A configuration method for configuring a device comprising a key memory (MEM) in which

- At least a predetermined set of key parts (Kxn) for the device determined and assigned to the device and stored in the key memory (MEM) and the at least one predetermined key subset (Kxn) comprises at least two secret keys and each a unique subset of at least one predetermined key amount (Kx) represents which is give in common pre multiple devices ^¬, and - a predetermined identifier (ID) determined for the device and the device is associated, which is representative of that key of the at least one predetermined Schlusselmenge (Kx) in the at least one given Key part quantity (Kxn) are included.

14. A configuration device for configuring a device comprising a key memory (MEM) formed

- For determining at least one predetermined set of key pieces (Kxn) for the device and for assigning the at least one predetermined key subset (Kxn) to the device and for storing the at least one predetermined key subset (Kxn) in the key memory (MEM) and the at least one predetermined key subset (Kxn) min ^¬ least includes two secret keys and each represents an unambiguous ^¬ a subset of GE (Kx) represents at least a predetermined Schlusselmen-, the gene common to several Vorrichtun- is predetermined, and

- for determining a predetermined identifier (ID) for the apparatus and for allocating the predetermined identifier (ID) to the device, and the predetermined identifier (ID) representa tive ^¬ is as to which key of the at least one predetermined Schlusselmenge (Kx) in the at least one pre give ^¬ NEN Schlusselteilmenge (Kxn) are included.

A system comprising at least two devices according to any one of claims 1 to 12 which are coupled together to form a network.