EP1483745A2

EP1483745A2 - Device and method for assessing the safety of systems and for obtaining safety in systems, and corresponding computer program

Info

Publication number: EP1483745A2
Application number: EP03706283A
Authority: EP
Inventors: Pio Torre Flores; Andreas Lapp; Wolfgang Laengst
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2002-03-01
Filing date: 2003-02-06
Publication date: 2004-12-08
Also published as: WO2003075104A2; WO2003075104A3; US7469170B2; JP4382494B2; DE10208866A1; US20050223263A1; JP2005518992A

Abstract

Disclosed are a method, a device, and a computer program for performing a safety check in systems, particularly in a motor vehicle, said systems or the at least one system comprising several components between which communication links exist. The components and the communication links thereof form a functional structure of the systems or the at least one system. Errors are detected according to the functional structure, and said error dependencies regarding the functional structure are evaluated.

Description

Establishment and procedure for the assessment and achievement of security in systems as well as appropriate computer program

State of the art

The invention relates to a device and a method for assessing the security of systems, in particular in a motor vehicle, in an early phase of product development, and to a corresponding computer program or computer program product according to the preambles of the independent claims. The method according to the preamble of the independent claim corresponding category is called CARTRONIC ^® based security analysis (CSA) and carried out accordingly by the facility or when the computer program is executed.

The challenge not only for the automotive industry is to meet increasing requirements for safety and reliability while shortening product development cycles. These boundary conditions make it necessary

Consider safety considerations very early on in product development. A short period of time from the start of planning to market launch is a decisive competitive advantage in order to establish a product in front of the competition on the market. The Consideration of a safety analysis in an early phase of product development should reduce and ideally avoid lengthy iterations for testing and improving the product in an advanced phase of product development. In an early

The development phase is an abstract way of looking at a system, ie it is known which functions the system should perform and how these functions interact. However, it has not yet been determined how these functions will be implemented (e.g. hardware, software, mechanics). This abstract perspective can be represented by the CARTRONIC ^® structuring concept, which is independent of the automobile manufacturer and supplier. This structuring concept forms the basis for the CARTRONIC ^® based security analysis. The increasing complexity, particularly of the motor vehicle system, is due on the one hand to the increasing complexity and number of the individual subsystems, but is also significantly influenced by their increasing networking. The complexity of the motor vehicle system can be controlled by structuring the subsystems according to CARTRONIC ^® , taking into account the interactions with other subsystems.

The CARTRONIC ^® structuring concept (see Bertram, T., - Bitzer, R.; Mayer, R.; Volkhart, A.; 1998, CARTRONIC - An open architecture for networking the control Systems of an automobile, Detroit / Michigan USA, SAE 98200 ) is based on an object-oriented approach. The motor vehicle system is structured into logical functional units that communicate with one another via standardized interfaces.

CARTRONIC ^® is a structuring concept for all control and regulation systems of a vehicle. The concept contains modular and expandable architectures for "Function" and "security" on the basis of agreed formal structuring and modeling rules.

An architecture is to be understood here as the structuring system (rules) as well as its implementation in a concrete structure. The functional architecture encompasses all control and regulation tasks occurring in the vehicle. The tasks of the system network are assigned to so-called functional components, the interfaces of the components (functional interfaces) and their interaction are defined. The security architecture extends the functional architecture by elements that guarantee the safe operation of the system network.

Another form of representation results from mapping in UML (Unified Modeling Language), which also facilitates porting to a computer system. The mapping of a CARTRONIC ¹¹⁹ functional structure into a UML model is described in (Torre Flores, P.; Läpp, A.; Hermsen, W.; Schirmer, J.; Walther, M.; Bertram, T .; Petersen, J .; 2001, Integration of a structuring concept for vehicle control Systems into the Software development process using UML modeling methods, Detroit / Michigan USA, SAE 2001-01-0066).

The basic structure for structuring is the functional component. A functional component represents a function in the motor vehicle system. In the following, instead of the term functional component, only the term component is used in favor of a compact representation. The components can be refined in the course of development

(detailed), while the higher-level function is retained as a shell. The higher-level function is in turn composed of components within the refinement (detailing), the individual parts of the higher-level function represent. There are three different types of components in the structuring concept:

□ Components with predominantly coordinating and distributing

Tasks, Q components with mainly operational and executive

Tasks and Q components that only generate and provide information.

In the communication relationships, a distinction is made between an order (with confirmation), a query (with notice) and a request. The order marks the obligation to execute; in the event of non-performance, the contractor must send a feedback to the client describing the reason for the non-execution. The query is used to obtain information for an order execution. In the event that a component cannot provide the requested information, it gives an indication to the component in question. A requirement describes a "wish" that a function is performed by another component. However, the requirement is not linked to the requirement to fulfill, which is taken into account, for example, in the case of competing requirements. Table 1 summarizes the structural elements.

Table 1

The structuring rules describe permitted communication relationships within the architecture of the overall vehicle. A distinction is made between structuring rules that define the communication relationships on the same level of abstraction and in higher and lower levels, taking into account the specified boundary conditions. Furthermore, the structuring rules clarify the forwarding of communication relationships into the detailing of another functionality.

A structure developed according to the structuring and modeling rules is characterized by the following features:

□ agreed, uniform structuring and modeling rules on all abstraction levels,

□ hierarchical order flows,

Q high individual responsibility of the individual components,

□ Control elements, sensors and estimators are equivalent information providers and one

□ Encapsulation that makes each component as visible as necessary and as invisible as possible to the other components. It is therefore the task of generating a method and a device as well as a corresponding computer program and computer program product, which enables an improved security analysis and generation of an improved security structure of at least one system, in particular in a motor vehicle.

Advantages of the invention

The invention relates to a device, in particular a computer system, and a computer program or

Computer program product, as well as a method for performing a safety analysis in systems, in particular in a motor vehicle, the systems or the at least one system consisting of several components between which there are communication relationships, the components and their communication relationships being a functional structure of the systems or the at least one system form, errors advantageously being determined as a function of and ^■ the functional structure

Error dependencies regarding the functional structure can be evaluated.

In one embodiment, the invention shows a device, in particular a computer system, and a computer program or computer program product, and a method for achieving a predefinable security level in systems, in particular in a motor vehicle, the systems or at least one system consisting of several components, between which

Communication relationships exist, the components and their communication relationships forming a functional structure of the systems, errors being determined depending on the functional structure and this Error dependencies regarding the functional structure are evaluated with the following steps:

a) Tracking the error dependencies in the functional structure and generation of error paths and determination of global

Impact of the errors, b) Assessment of the global effects depending on predefinable security levels, c) Determination of errors that cause a component or communication relationship to malfunction, d) Assignment of a component or communication relationship to the global effects e) Determination of measures for error detection and / or error control, f) determining the achievable security level and comparing the determined security level with the security level to be achieved and g) depending on the comparison, starting the process again at a) until the security level to be achieved is achieved.

A safety analysis is thus advantageously carried out in an early phase of product development, in order to recognize problem areas in good time and the early integration of safety measures into the functional structure (“safety through design”).

The security analysis according to the invention is therefore expediently also represented as an iterative analysis and improvement process.

The method for assessing the security of systems can advantageously be represented on the basis of CARTRONIC® ^" functional structures or CARTRONIC ^ -UML models, but can also be applied to other system models. The method is expediently carried out using the CSA table. Global effects of errors are identified and evaluated using the CSA table. It documents error dependencies of components and

Communication relationships. Misconduct is caused by functional structure errors (FS errors) in components or communications. Communication errors (orders, requests) are taken into account in the target component of the communication. FS errors in queries are taken into account in the source component of the communication.

Malfunction of the components is assigned to the global impact. This not only enables an assessment of global conditions, but also which components of the functional structure are responsible for this.

In a special embodiment, the method is integrated in a CARTRONIC ^® -based development process. This promotes a formal, systematic approach.

The security measures are mapped in particular in a CARTRONIC ^® - UML model. This enables a formal verification against specified product requirements or the product specification. A validation of the product specification is also possible with this procedure.

It is therefore advantageous to carry out further quantitative safety considerations based on the CSA table, the CARTRONIC ^® function structure or the CARTRONIC ^Φ - UML model, including safety measures. Further advantages and advantageous configurations result from the description and / or the features of the claims.

drawing

The invention is explained in more detail below with reference to the drawings and tables represented by the figures.

1 shows the method and the procedure for the security analysis.

Figure 2 shows the CARTRONIC ^® functional structure of an exemplary considered brake system.

FIG. 3 shows an example of a UML modeling of the CARTRONIC function structure according to FIG. 2.

Figure 4 shows the table header of the CSA table with the global effects.

FIG. 5 shows the assignment of the effects of errors to the security levels in a flow graph.

Figure 6 shows an example of an assessment of the global impact.

FIG. 7 shows the propagation of errors in the functional structure or the assignment of FS errors to the global effects. FIG. 8, consisting of the individual figures 8a, 8b, 8c and 8d, shows the CSA table, that is to say the safety table, according to the example according to FIG. 2 with the corresponding identifier.

Figure 9 shows the classification of the CSA in a development process, in particular according to the V-model

Description of the embodiments

The security analysis described below is based on the CARTRONIC ^® functional structure or the CARTRONIC ^® UML model of the system under consideration. The CARTRONIC ^® UML model is the mapping of a CARTRONIC ^® functional structure into the UML (Unified modeling language). The mapping into the UML provides a formalized and more precisely specified representation which facilitates an automated implementation of the invention. The mapping of a CARTRONIC ^® functional structure into a UML model is described in (Torre Flores, P.; L pp, A.; Hermsen, W.; Schirmer, J .; Walther, M.; Bertram, T .; Petersen, J .; 2001, Integration of a structuring concept for vehicle control Systems into the Software development process using UML modeling methods, Detroit / Michigan USA, SAE 2001-01-0066).

The CARTRONIC ^® based security analysis is a procedure for systematic security analysis at an abstract system level and thus supports the development credo "safety through design". The procedure for CARTRONIC ^® based security analysis described in a previous publication (Bertram, T .; Dominke, P.; Müller, B., 1999, The Safety-Related Aspect of CARTRONIC, Detroit / Michigan USA, SAE '99, Session Code PC 26) is fundamentally revised and expanded to include the analysis of structural error dependencies and the causes of which are described in an abstract manner, for example "errors present" or "errors not present" The method thus represents an abstraction of the FMEA (Failure Mode and Effects Analysis or Failure Possibility and Effect Analysis), which is expanded to include structural analysis

Error dependencies. The FMEA is a recognized methodical procedure for the analysis, evaluation and documentation of systems, components and manufacturing processes and serves primarily to avoid errors. The intention of the CSA is not to replace an FMEA, but only to support the system developers in the early development phase in identifying potential danger spots.

Important terms are first defined before the invention is then explained using an example.

Definition 1 (global impact)

Global effects are physical effects that affect the overall motor vehicle system through actuators. You will be noticed by sensors (or a vehicle driver) through loss of function (e.g.

Failure of the braking system) or loss of comfort (e.g. by switching off assistance systems such as Adaptive Cruise Control).

Definition 2 (functional structure errors) Functional structure errors (FS errors) are errors that a

Cause component or communication to malfunction.

Definition 3 (functional structure error causes)

Function structure error causes (FS error causes) are reasons for a component to behave incorrectly. The reason for a component to malfunction is the presence of FS errors. FS errors can be further divided into refined error types. The refined types of errors are then again the cause of the FS errors. The refined types of errors can be:

Component failure:

Component dead

Component calculates incorrect values

Component is active in an uncontrolled manner

Component generates result at the wrong time

Communication error :

Communication interrupted

Communication provides wrong information

Communication is active in an uncontrolled manner

Communication provides information at the wrong time

Communication is misdirected

Figure 1 shows the procedure of the CARTRONIC ^® based security analysis. The procedure can be structured as follows:

Step 1: Identify global impacts based on the CARTRONIC ^® functional structure or the

CARTRONIC ^® UML model Step 2: Assess global impacts through

Security levels (SL) Step 3: Analysis of FS error causes (see definition

3), i.e. Component failure or

Analyze communication relationships Step 4: Assignment of a component's misconduct to the global effects Step 5: Measures for error detection and / or

Determination of control Step 6: Creation or addition of a CARTRONIC ^® -

Security structure step 7: verification of the resulting functional and

Security structure under security aspects In the following the procedure of the CARTRONIC ^® based security analysis is described using an example. A simplified braking system was chosen as an example. The CARTRONIC ^® functional structure and the CARTRONIC ^® -UML model of the simplified braking system are shown in Figure 2 and Figure 3. The example system consists of the components torque distributor, propulsion, braking system,

Brake system coordinator, brake actuator and brake light. In the logical, hierarchical functional structure of CARTRONIC ^® , the components of the brake system coordinator and brake actuator are in the detailing of the brake system. The components N02r1e.n distributor, propulsion and brake system are details of the propulsion and brake. In the functional structure, propulsion and braking is a detailing of the vehicle movement. The brake light component is in the detailing of light and light signals, which is a detailing of exterior lighting. This in turn is a refinement of the visibility and signaling components in the body and interior. The detailing of the vehicle movement and body and interior are placed on the vehicle level. The vehicle level is the top level of the CARTRONIC ^® functional structure. The torque distributor is responsible for distributing the torque requests of the driver. The components of the brake system coordinator and propulsion request moments from the torque distributor via the communications R1 and R2. If there is only one request from jacking, the torque distributor queries the minimum and maximum permissible torque values from the jacking component through communication II and then ensures implementation by order 02.If there is only one request from the braking system, it is answered by the Order 01 realized. If there are requirements for propulsion and braking system, the braking system has priority. The brake system coordinator component in the detailing of the brake system ensures that the moments are implemented by request 03 to the brake actuator and with request R3 that Activation of the brake light, so that the driver's request is signaled to following vehicles.

The findings of the CARTRONIC ^® -based safety analysis are summarized and saved in the form of a table, the CSA table.

The CSA table provides an assignment of a malfunction of an individual component to error dependencies within the functional structure. The FS errors documented in the CSA table can be those listed above

Error types can be refined. The refined types of errors can be interpreted at the abstract system level as the cause of the FS errors. Furthermore, the "internal effects" (misconduct of a component) are assigned to the global effects. In this way, complex dependencies between

Structure-dependent error dependencies and global effects can be seen.

The procedure described below represents the cause analysis is a "bottom-up" approach, since the possible causes are identified on the basis of a potential misconduct. The procedure is now explained using the example explained above and steps 1-7 already described:

Step 1: identify global impacts

Global effects arise when considering the system interface to the environment. The actuators, which are controlled by the subsystem under consideration, represent the interfaces to the environment. In the context considered here, the environment means the motor vehicle as a whole. The actuators for the example system shown in FIG. 2 and FIG. 3 are the brake system or, in the detailing, the brake actuator, the Propulsion and the brake light. Only those global effects are considered and, for example, recorded in a computer system that are the responsibility of the subsystem to be examined. For example, it does not make sense for you to have the Adaptive Cruise Control (ACC) subsystem that controls the braking system

Blame total loss of braking effect. These correlations can be recorded using assignment tables or expert systems and are made accessible in the course of the process by the computer system. In an iterative procedure, different relationships in the form shown above can then be used depending on the iteration process. This also applies to the further procedure as described below.

For the example shown in FIG. 2, the following global effects can be identified, for example: Q acceleration effect - propulsion

• Uncontrolled acceleration o Acceleration too strong o Acceleration too weak

• No acceleration

□ Braking effect - ^ brake actuator

• No braking effect

• Insufficient braking effect

□ Signaling -> brake light

• No display

• Continuous display (contains scenario brake light is on, although there is no braking)

FIG. 4 shows the table header with the global effects of the CSA table.

Step 2: Assess global impacts through security levels The assessment of the global effects is based on the requirement classes defined in DIN V 19250. The requirement classes in the standard are generally defined for MSR protective devices (MSR - measuring, controlling, regulating). The requirements set out there cannot be directly applied to motor vehicles. The points flow in this standard

□ length of stay in the danger zone

□ one or more people are affected by the potential impact of an error in the assessment. In the case of motor vehicles, however, it is not sensible to take these cases into account. They are to be viewed on the premise that when certain machines are operated, a person who operates the machine operates them from a test bench and only under certain conditions for a limited period of time, e.g. during maintenance work, is exposed to a potential danger. In the motor vehicle, however, you are constantly exposed to a potential danger. In addition, several people can always be affected by the effects of an error. With this in mind

There are objections to adapted “requirement classes” for automobiles, which are referred to as safety levels (SL) in the context of the CSA. The assignment of the safety levels to the effects of errors is shown in the risk graph of FIG. 5.

A distinction is made between whether an impact occurs in individual cases or as a rule. In individual cases, this means that in the overwhelming majority of cases the corresponding impact should not be expected. Event frequencies can be assigned to the security levels. Such

The frequency of events is to be understood as the target quantity that must be at least fulfilled by the later implementation of a component. An a priori verification of the event frequencies is generally not possible, since reliable data is often only available after a series application. However, it is possible to subsequently compare the setpoint of the event frequency associated with a security level with a recorded actual value. If there is a discrepancy, ie the event frequency actually determined is greater than the permissible event frequency of a security level, we must

Measures to reduce the frequency of events are taken.

FIG. 6 shows the assessment of the global effects of the braking system by means of security levels. A braking system is an extremely important functionality of a motor vehicle, which must be guaranteed under all circumstances. The global impact "no braking effect" generally represents a threat to life and limb that cannot be controlled by the driver. Therefore, security level SL4 must be assigned here. For the impact "no acceleration", security level SLl is assigned because here in As a rule, it can be assumed that maximum minor injuries can be expected, e.g. due to rear-end collisions with low speed difference. In individual cases, there may be a risk to life and limb that is manageable, e.g. switch on the hazard warning lights.

In order to obtain a clear overview in the following, the table column "Uncontrolled Acceleration" is not refined.

Step 3: functional structure failure cause analysis

The root cause analysis asks the question: What causes a component to malfunction {torque distributor, propulsion, brake system, brake system coordinator, brake actuator, brake light}?

The cause analysis examines what could lead to a malfunction of the CARTRONIC ^® components (torque distributor, propulsion, brake system, brake system coordinator, brake actuator, brake light). A misconduct is investigated by Components and their details, insofar as they are known. For the cause analysis, the CARTRONIC ^® function structure of the system under consideration is adopted in the "Function structure" header of the CSA table. In addition, the CARTRONIC ^® function structure is adopted in the "Components malfunction" column (see Figure 7).

If an FS error in a component causes a malfunction in the same component, the component is assigned from the functional structure to a malfunction in the same component (marked with "x", see FIG. 7).

In addition, FS errors of the communication relationships that are relevant for the component are also taken into account. If an FS error in a communication relationship causes misconduct, an assignment to the functional structure is also made, which reflects the type and name of the communication under consideration. The type of communication relationship is identified with the uppercase initial letter of the English expression of communication. As a result, an "0" is used for an order, an "R" for a request, and an "I" for an inquiry. An underscore follows the type of communication " _ ", followed by the name of the communication relationship (eg I_I1).

When analyzing the cause of a component failure, the Q component itself, as well

□ incoming orders

□ incoming requests Q outgoing queries considered. In the further course, the error dependencies are examined. It is thus determined which other components and communications can be responsible for a malfunction of the component under consideration. For this, the communication (s) in column M of a component traced and the newly found component (s) assigned to the component malfunction in the same line. One of the newly found components serves as a new starting point. The communication (s) assigned to this component are determined and recorded in column M of the corresponding component. The communications associated with this component are in turn traced. This will find new starting components. This process is continued iteratively until no further communications are available or all accessible components have been run through (see the following example and FIG. 8).

Example:

A malfunction of the component torque distributor (fc. ^) Is due to the fact that a component error in the component torque distributor (fc ₁ ) itself

Communication error in query II or request Rl or request R2, a component error in the propulsion component (fc ₃ ) or a communication error in order 02 or a component error in the component

Brake system coordinator (FC ₂₁ ) or occurred in order 01.

The brake system component (fc ₂ ) has malfunctioned

The reason for this is that there is either a component fault in the brake system (fc ₂ ) itself or a

Communication error in order 01 or a component error in the torque distributor (fc with the potential communication errors to be considered here, request Rl, request R2 and query II, or an error in the propulsion component (f ^c ₃ ) or a communication error in order 02.

The entries in the CSA table for the example shown in FIG. 2 can be seen in FIG. 8, in particular FIG. 8a.

If a malfunction of a component is considered in the refinement, the envelope for the cause analysis is not from Interest, since only communication relationships from the higher level are forwarded to the 'refinement. The column brake system (brake system (fc ₂ ) is the envelope of the brake system coordinator and brake actuator) of the "functional structure" must be used for the cause analysis

Misconduct of the component brake system coordinator (line brake system coordinator (fc ₂₁ ) in the column "Misconduct component") are not taken into account. When analyzing the cause of a misconduct of the component brake light, it is not necessary to carry out the analysis for the component brake system if the analysis for the refinement of the Brake system component was carried out Possible causes are already taken into account when considering the refinement (brake system coordinator and brake actuator).

The CSA table thus enables logical error dependencies to be tracked. The columns of the function structure with many entries, e.g. column torque distributor (fc _x ) and column propulsion (fc ₃ ), are important components, since an error affects large parts of the system.

Step 4: Mapping a component's misconduct to its global impact

First of all, the global impacts identified in step 1 are assigned to the components whose misconduct causes a global impact. These components are the system interfaces (see step 1).

This assignment is already shown in step 1.

□ Acceleration effect -> malfunctioning propulsion Q braking effect -> malfunctioning brake actuator

Q signaling -> malfunction of brake light

This assignment in the CSA table can be seen in FIG. 8b. The error dependencies that were determined in step 3 provide an assignment of the other components to the global effects. This is achieved by looking at the columns of the functional structure for the rows of the system interfaces (malfunction of the components brake actuator (fc ₂₂ ), propulsion (fc ₃ ) and brake light (fc ₄ )). Each column of the functional structure that is assigned to a malfunction of the system interfaces, ie marked with an "x", can cause the same global effects. The shell of a detail is assigned all global effects that are assigned to the components of the detail The result of this step is shown in FIG. 8c.

Example: In the following, the component torque distributor (fc _α ) is considered in the functional structure. The component Nominal distributor (fC _j ) in the functional structure is assigned to the line Brake actuator malfunction (fc ₂₂ ), ie an FS error in the Torque distributor component can cause the brake actuator to malfunction. It can be concluded from this that a malfunction of the torque distributor component can also cause the global effects of the brake actuator. The global effects of a malfunction of the brake actuator ("no braking effect" and "insufficient braking effect") are thus also

Misbehavior assigned to the torque distributor. In addition, an FS error in the torque distributor component (fc _x ) can cause propulsion to malfunction (fc ₃ ). A malfunction of the torque distributor component can therefore also have the global effects of "uncontrolled acceleration" and "no acceleration". An FS error in the torque distributor component (fc _χ ) can cause the brake light (fc ₄ ) to behave incorrectly. Thus, a malfunction of the torque distributor component can cause the global effects "no display" and "continuous display". A malfunction of the brake system (fc ₂ ) as a shell of the components brake system coordinator (fc _2X ) and brake actuator (fc ₂₂ ) can cause the global effects of all its components in the detailing.

Step 4.1: Assign security levels to component malfunction

The maximum value of the security level of global effects, which is assigned to a misconduct in a row, is entered in the corresponding element of the SL column. The procedure is illustrated in Figure 8d.

Step 5: measures for error detection and / or control

The following two tables contain measures for error detection and control for components (Table 2) and communication relationships (Table 3).

Table 2: Compilation of measures for error detection and control for functional components.

Table 3: Compilation of measures for error detection and control for communication relationships

It is difficult to specify measures for error detection and / or error control at a high level of abstraction if there is no concrete system implementation yet. For many abstract errors in the CSA table only effective and economically sensible can be

Specify measures for error detection and control if these are specified depending on the implementation, i.e. for a concrete system topology. When looking at the implementation independently, there are otherwise too many options that can be given at the abstract level for a solution (cf.

Table 2 and Table 3). The measures indicate possibilities for recognizing and mastering the abstract causes. These abstract causes can be understood as error modes (types of errors) of the more general FS errors (see definition 3). At a high level of abstraction, measures can be specified that are already evident in an early development phase.

This includes measures that prevent the spread of errors or are based on plausibility. So it can be obvious that a signal may only lie within certain limit values. Error propagation can be limited by redundancy.

Redundant structures can be used in later development phases, i.e. with detailed knowledge of the implemented topology can be converted into cost-effective measures. Examples of this are codes for error detection and correction. The plain text information in the tables is in the program or

Computer system can be shortened and assigned by coding.

An optimal technical and economical solution can only be found if one considers an error within a known topology. If the cause "provides incorrect information" is identified as critical for a query, the measure to be taken depends very much on how the query is implemented. If the value is queried within a processor system (eg internal memory), there may be none Measure to be taken (intrinsically safe) or you can consider the processor system as an entire unit and thus monitor a large number of operations with a single measure, for example watchdog timers. If the communication runs over an external connection (cable, bus system), the connection / message transmission may have to be designed redundantly. In the case of EMC problems, it may be sufficient to be able to guarantee a connection via a shielded cable without any additional electronic effort.

Step 6: CARTRONIC ^® - security structure

The CARTRONIC ^® representation of a system (shown for an example in FIG. 2) can be mapped into a CARTRONIC ⁸¹ -UML model (FIG. 3). This allows a more formal system specification than CARTRONIC ^® . UML is also an internationally standardized language. To describe a system topology, however, it is necessary to expand the existing CARTRONIC ^® -UML model. The extension must include the mapping of measures for error detection and control, the partitioning of the functions on control units and the representation of temporal and logical processes. The expanded structure can be used to document the security measures used. A representation in which structure, functionality and topology are included is also suitable for future quantitative system analyzes, in particular for automated implementation.

Step 7: verification

During the verification, it is checked whether the results of the CARTRONIC ^® based safety analysis lead to a product specification being met. It is examined whether the assigned security levels correspond to the requirements of the specification, i.e. whether the security levels to be achieved correspond to those that can be specified and thus achieved. Is this If this is not the case, a further iteration of the CARTRONIC ^® based security analysis can be carried out. This iterative improvement process continues until all requirements of the specification or the specified security levels are met.

FIG. 12 shows the classification of the CSA in a development process. The development process used is based on the V-model. The V-Modell is a federal development standard for IT systems. It is possible to adapt the V-Modell to specific project conditions. This process is called tailoring. Activities (activities) and their products are defined in the V-Modell. The incremental, iterative V-model (UV-model) adapted for the CARTRONIC ^® based development process is applied on the three levels system level, subsystem level and partial realization level. The IIV model is navigated along the arrows. It is possible to go from the left to the right side of a level of the V-model (test cases) and back (iterations). Several increments are also possible between the levels. At the partial implementation level, it can be recognized, for example, that additional functions are required for implementation. An additional increment can then be run through by introducing the functions and their interactions at the subsystem level and then implementing them at the partial implementation level. At the system level, the motor vehicle is viewed as a whole. The subsystem level details the overall motor vehicle system in subsystems. These subsystems can be, for example, the engine control, the brake system, the transmission or an adaptive cruise control. The subsystem level represents the subsystems of the motor vehicle independently of the implementation, ie only the functionality but not the technical implementation is considered. On the

At the partial realization level, each subsystem is further detailed. A decision is made about a topology and whether a function as software, computer hardware, hydraulics, electronics, electrics, mechanics, etc. is implemented. A corresponding subsystem is then created and, if necessary, the software is implemented. At each level of the IIV model, a requirements analysis is carried out on the left side of the V model and a draft is drawn up. The right side of the IIV model is used for integration and verification of the draft created at the corresponding level. In addition to the processes described, a validation can be carried out at the system level. A validation checks whether the system specification meets the requirements placed on it. The verification, however, checks a product against the specification. The steps 1 to 5 are described in the

Subsystem level analysis phase performed. Step 6 is implemented in the design phase of the subsystem level. Based on the considerations in step 5, namely that a specification of measures for error detection and control often only makes sense with a known system topology, one is recommended

To detail the security measures in step 5 and step 6 on the partial realization level. In this phase the system topology, ie the partitioning of the functionalities on control units, is carried out and the functional realizations are defined. The CSA as described here is mainly used at the subsystem level. However, it is advantageous to continue the CSA at the partial realization level. Here, a requirement analysis is carried out, how security measures are to be designed depending on the topology and the implementation of the subsystem, and a corresponding draft is made. This design and its integration can be verified on the right side of the IIV model. The invention shown can run automatically on a computer system. For this purpose, the individual steps or parts of these steps as well as the tables can be represented as a computer program with data and commands, so that steps 1 to 7 can be stored as program code and executed in a device, in particular a computer system, in order to carry out a method according to the invention. Any conceivable form, such as CD-ROM, DVD, diskette, EPROM, FlashEPROM, ROM, RAM, etc., can be considered as the memory or data carrier, as a result of which a computer program product is present in connection with the computer program. In particular, a transfer of the program via networks such as the Internet from one memory to another memory or network participant is also included.

Claims

Expectations

1. Method for carrying out a security analysis in systems, in particular in a motor vehicle, the systems or the at least one system consisting of several components between which there are communication relationships, the components and their communication relationships forming a functional structure of the systems or of the at least one system, characterized in that errors are determined depending on the functional structure and these error dependencies regarding the functional structure are evaluated.

2. The method according to claim 1, characterized in that the error dependencies in the functional structure are tracked, whereby error paths are generated, global

The effects of the errors can be determined as the conclusion of the error paths.

3. The method according to claim 1, characterized in that the error dependencies in the functional structure are tracked, whereby error paths are generated, global effects of the errors being determined and evaluated as the conclusion of the error paths.

4. The method according to claim 3, characterized in that the global effects are assessed by determining at least one security level.

5. The method according to claim 1, characterized in that, in addition to the error dependencies with respect to the functional structure, errors are determined which cause a component or a communication relationship to malfunction.

6. The method according to claim 2 or 3 and 5, characterized in that incorrect behavior of a component or a communication relationship are assigned to the global effects.

7. The method according to any one of the preceding claims, characterized in that measures for error detection and / or error control are determined.

8. The method according to any one of the preceding claims, characterized in that the functional structure is expanded such that the global effects and / or that misconduct of a component or a communication relationship is taken into account.

9. The method according to any one of the preceding claims, characterized in that the functional structure is expanded to include measures for error detection and / or error control.

10. Method for achieving a predefinable security level in systems, in particular in a motor vehicle, the systems or at least one system consisting of several components between which there are communication relationships, the components and their communication relationships form a functional structure of the systems, errors being determined depending on the functional structure and these error dependencies relating to the functional structure being evaluated with the following steps:

a) Tracking the error dependencies in the functional structure and generation of error paths as well as determining the global effects of the errors, b) Assessing the global effects depending on predefined security levels, c) Determining errors that cause a component or a communication relationship to malfunction, d) Assignment the faulty behavior of a component or a communication relationship to the global effects e) determination of measures for error detection and / or error control, f) determination of the achievable security level and comparison of the determined security level with the security level to be achieved and g) depending on the comparison of a new process start a) until the security level to be achieved is achieved.

11. The method according to claim 10, characterized in that between the steps e) and f) the functional structure is documented.

12. The method according to any one of the preceding claims, characterized in that the functional structure as CARTRONIC ^® - functional structure using the UML is illustrated.

13. A device, in particular a computer system, for carrying out a method according to at least one of claims 1 to 12.

14. Computer program which, when running in a device according to claim 13, executes a method according to at least one of claims 1 to 12.

15. Computer program product, in particular a data carrier with a computer program according to claim 14, which carries out a method according to at least one of claims 1 to 12 when introduced into a device according to claim 13.