DE102017128421A1 - Method for the secure exchange of data by radio in automation technology - Google Patents

Abstract

The invention relates to a method for the secure exchange of data by radio between at least one field device (1) of automation technology and an operating tool (2) for operating the at least one field device (1), the method comprising the following method steps:
during commissioning of the field device (1), a code is input by an operator via a first input unit (3) assigned to the field device (1); Based on the at least four-digit code, a pseudorandom number is generated as a network key in the at least one field device (1) via a pseudo-random number generator (4), the pseudo-random number having more digits than the four-digit code; in the operating tool (2), the same at least four-digit code is entered via a second input unit (5) or the at least four-digit code is read from a memory (6) assigned to the operating tool (2); the same pseudo-random generator (4) assigned to the operating tool (2) generates the same pseudo-random number for the operating tool (2) as a network key; Between the operating tool (2) and the at least one field device (1), data is transmitted via a radio link secured by the generated network key.

Description

The invention relates to a method for the secure exchange of data by radio between at least one field device of the automation technology and a control tool for operating the at least one field device. Furthermore, the invention relates to a device for carrying out the method.

In process automation technology as well as in factory automation technology, field devices are often used to detect and / or influence process variables. Measuring devices or sensors, such as level gauges, flowmeters, pressure and temperature measuring devices, pH redox potential measuring devices, conductivity measuring devices, etc., which record the corresponding process variables level, flow, pressure, temperature, pH value or conductivity, are used to record process variables. To influence process variables are actuators, such as valves or pumps, via which the flow of a liquid in a pipeline or the level can be changed in a container.

In the context of the invention, field devices are in principle all devices which are used close to the process and supply or process the process-relevant information. In addition to the abovementioned measuring devices / sensors and actuators, field devices generally also refer to those units which are connected directly to a field bus and serve to communicate with the higher-level units, such as, for example, Remote I / Os, Gateways, Edge Devices, Linking Devices and Wireless Adapters.

A large number of such field devices are manufactured and distributed by the Endress + Hauser Group.

In modern industrial plants, field devices are generally distributed over fieldbus systems, e.g. Profibus®, Foundation Fieldbus®, HART®, etc. connected to a higher-level unit. The higher-level unit can be a control system or a control unit, such as a PLC (Programmable Logic Controller) or a PLC (Programmable Logic Controller). The higher-level units serve, among other things, for process control, process visualization, process monitoring and commissioning of the field devices. The communication on the bus system can be wired or wireless.

Usually, the field devices integrated in a fieldbus network can also be operated via an operating tool. The term "operating the field device" is understood in connection with the invention in particular the configuration and parameterization of the field device, but also the display or the collection of measurement, diagnostic and / or status information. Operation with the operating tool can be wired or wireless.

In many automation systems, the communication in the bus system must meet the highest safety requirements. Unauthorized interventions in the process running in the automation system and unauthorized manipulation of the field devices used must be reliably ruled out. This security aspect gains particular importance in wireless fieldbus networks.

From the prior art solutions have become known in which only those components communicate on a wireless network, which have the correct password or the correct network key. To minimize the likelihood of a successful hacker attack, the password must consist of as many digits as possible of different alphanumeric characters (numbers, letters, and special characters). This ensures that only authorized persons have access to the radio network, e.g. Make changes to parameters or retrieve information.

For the communication to be possible, a network key or a multi-digit code must be entered into the field device, in particular when the field devices are put into operation in the radio network. This input is manual and cumbersome, since field devices usually have only a few keys for entering data. Often, the input via DIP switches - an input that costs time, annoying and quite error-prone.

It is therefore an object of the invention to propose a method that allows a user-friendly commissioning of a radio network with multiple field devices.

• • bei der Inbetriebnahme des Feldgeräts wird über eine dem Feldgerät zugeordnete Eingabeeinheit ein Code von einer Bedienperson eingegeben,
• • anhand des zumindest vierstelligen Codes wird in dem zumindest einen Feldgerät über einen Pseudozufallsgenerator eine Pseudozufallszahl als Netzwerkschlüssel erzeugt, wobei die Pseudozufallszahl mehr Stellen aufweist als der vierstellige Code,
• • bei dem Bedientool wird über eine zweite Eingabeeinheit der gleiche zumindest vierstellige Code eingegeben oder der zumindest vierstellige Code wird aus einem dem Bedientool zugeordneten Speicher ausgelesen,
• • der gleiche, dem Bedientool zugeordnete Pseudozufallsgenerator erzeugt für das Bedientool die gleiche Pseudozufallszahl als Netzwerkschlüssel,
• • zwischen dem Bedientool und dem zumindest einen Feldgerät werden Daten über eine durch den erzeugten Netzwerkschlüssel gesicherte Funkverbindung übertragen.

The object is achieved by a method for the secure exchange of data by radio between at least one field device of the automation technology and an operating tool for operating the at least one field device. The process according to the invention comprises the following process steps:

• During commissioning of the field device, a code is entered by an operator via an input unit assigned to the field device,
• • Based on the at least four-digit code, a pseudo-random number is generated in the at least one field device via a pseudo-random generator generated as a network key, wherein the pseudo-random number has more digits than the four-digit code,
• In the operating tool, the same at least four-digit code is input via a second input unit or the at least four-digit code is read from a memory associated with the operating tool,
• The same pseudo-random generator assigned to the operating tool generates the same pseudorandom number for the operating tool as a network key,
• Between the operating tool and the at least one field device, data is transmitted via a radio link secured by the generated network key.

Pseudo-random numbers are understood to be numbers that appear unsystematic and random, but which reproducibly always have the same values. A network key, e.g. has at least 12 points, is hacker safe. Possibly. the determined pseudo-random number is converted into a character string consisting of numeric and alphanumeric characters.

A significant advantage of the invention is the fact that due to the reduced number of digits of the code to enter a wireless network can be taken much faster and safer in operation. Another advantage of the method according to the invention is the fact that a user does not know the multi-digit activation code that allows access to the network. The network key remains secret and can not accidentally or deliberately fall into the wrong hands.

In order to further increase safety, an advantageous further development of the method according to the invention provides that in addition to the at least four-digit code, a starting value for the pseudo-random generator is specified or that the starting value is entered freely selectable by the operator. This start value causes pseudorandom number series deviating from the at least 4-digit code to be generated by the same algorithm.

Preferably, an algorithm is selected as the pseudo-random generator for the network key, which is iteratively traversed n times until the code with the number of desired digits is generated.

If the control tool is an Internet-enabled device, e.g. a smart phone, a laptop or even an internet-enabled edge device, it is provided that the pseudo-random generator is loaded as an app or as part of an app in the operating tool.

A device suitable for carrying out the method according to the invention has at least one edge device and a multiplicity of field devices for determining and / or monitoring at least one process variable in automation technology. The Edge Device collects information about the data exchanged on a field-level network and translates the transmission protocol used in the field-level network to the transmission protocol used in a network at the control or operating level. For example, the transmission protocol used between the field devices at the field level is the WirelessHART protocol, while at the control and operation level, e.g. as transmission protocol an internet protocol is used.

• 1: eine schematische Darstellung einer Vorrichtung, die zur Durchführung des erfindungsgemäßen Verfahrens geeignet ist,
• 2: ein Flussdiagramm, das die einzelnen Verfahrensschritte des erfindungsgemäßen Verfahrens zeigt, und
• 3: eine Skizze, die zeigt, wie erfindungsgemäß der sichere Netzwerkschlüssel erzeugt wird.

The invention will be explained in more detail with reference to the following figures. It shows:

• 1 : a schematic representation of a device which is suitable for carrying out the method according to the invention,
• 2 FIG. 2 is a flowchart showing the individual method steps of the method according to the invention, and FIG
• 3 : a sketch showing how the secure network key is generated according to the invention.

1 shows a schematic representation of an apparatus which is suitable for carrying out the method according to the invention. The device or the system consists of a higher-level control unit 7 , at least one edge device 8th and a variety of field devices 1 for determining and / or monitoring at least one process variable in automation technology. The Edge Device 8th is used to collect or display measurement, diagnostic and / or status information. Furthermore, the edge device does 8th a conversion between a transmission protocol used in the network of the field level and a transmission protocol used in the network on the control or operating level. At least at the field level, communication takes place between the edge device 8th and the field devices 1 wireless. In the case shown, the communication takes place at the field level, eg via the WirelessHART protocol, while at the control or operating level, for example, an Internet protocol is used. It goes without saying, however, that the solution according to the invention is completely independent of the particular communication protocol used. In addition, as an "operating tool" of course not an edge device 8th be used. With the operating tool 2 It can also be a handheld, such as a smartphone or a laptop.

2 shows a flow chart, the essential procedural steps of the inventive method for the secure exchange of data by radio between at least one field device 1 automation technology and an operating tool 2 or Edge Device 8th visualized.

The program is under the program point 10 , preferably as part of a commissioning of the field device 1 via a field device 1 assigned first input unit 3 , a code Z entered by an operator (program item 11 ). In many cases it is the input unit 3 on the field device 1 a so-called DIP switch. Data input via such DIP switches is very cumbersome, so that any digit / number that does not have to be entered is associated with a considerable time saving. Based on the at least four-digit code Z is in the at least one field device 1 via a pseudo-random generator 4 a pseudo-random number K generated as a network key (program point 12 ). The pseudo-random number K has more digits than the four-digit code. For example, the pseudo-random number has K 12 Put. Corresponding network codes K are considered hackersicher.

With the operating tool 2 or Edge Device 8th is via a second input unit 5 the same at least four-digit code entered or the at least four-digit code is from a the operating tool 2 / 8th associated memory 6 read out (program point 11 ). The pseudo-random generator 4 , the one pseudo-random generator 4 corresponds to the field device or the field devices 1 is assigned, thus also generated for the operating tool 2 / 8th the same pseudo-random number as network key (program point 12 ). Below is data between the operating tool 2 / 8th and the at least one field device 1 via a through the generated network key K secured radio connection are transmitted (program point 13 , Program point 14 ).

The sketch in 3 illustrates how the secure network key according to the invention K is produced. In addition to the at least four-digit code Z becomes a start value or an initial value S for the pseudo-random generator 4 entered. Alternatively, it is provided that the starting value is entered freely selectable by the operator. As a pseudo-random generator 4 for the network key K is an algorithm PZ chosen, iteratively iterated n times. With the field devices 1 is the pseudo-random generator 4 usually in memory 6 of the field device 1 deposited, or he is - preferably before commissioning - in the field device 1 loaded. With the operating tool 2 can be the pseudo-random generator 4 Part of an app or part of the app of the operating tool 2 his. The app can, for example, also from the Internet in the operating tool 2 Loading. After the nth iteration of the algorithm PZ is the network key K is generated and used during the subsequent operation of the wireless network for the communication of data. Only field devices 1 , Operating tools 2 or edge devices 8th that are above the identified network key K can participate in the data exchange on the wireless network.

LIST OF REFERENCE NUMBERS

1:

field device

2:

operating tool

3:

first input unit

4:

pseudo-random generator

5:

Second input unit

6:

Storage

7:

Parent control unit

8th:

Edge device

10-14:

program points

Z:

code

K:

key

S:

initial value

PZ:

algorithm

Claims (7)

Method for the secure exchange of data by radio between at least one field device (1) of automation technology and an operating tool (2) for operating the at least one field device (1), the method comprising the following method steps: during commissioning of the field device (1) a code (Z) is input by an operator via a first input unit (3) assigned to the field device (1), a pseudo-random number (K) is entered in the at least one field device (1) via a pseudo-random number generator (4) ) generated as a network key, wherein the pseudo-random number (K) has more digits than the four-digit code (Z), in the operating tool (2) is input via a second input unit (5) the same at least four-digit code (Z) or at least four-digit code (Z) is read from a memory tool (2) associated memory (6), the same, the operating tool (2) associated pseudo-random generator (4) erze generates the same pseudo-random number (K) as the network key for the operating tool (2), between the operating tool (2) and the at least one field device (1), data is transmitted via a radio link secured by the generated network key (K). Method according to Claim 1 , wherein in addition to the at least four-digit code (Z), a start value (S) for the pseudo-random generator (4) is predetermined or wherein the starting value (S) is entered freely selectable by the operator. Method according to Claim 1 or 2 , where as pseudo-random generator (4) for the network key (K) an algorithm (PZ) is selected, which is iteratively traversed n times. Method according to at least one of the preceding claims, wherein the pseudo-random generator (4) is loaded as an app or as part of an app in the operating tool (2). Device for carrying out in at least one of Claims 1 to 4 described method, with a higher-level control unit (7), at least one edge device (8) and a plurality of field devices (1) for determining and / or monitoring at least one process variable in automation technology, wherein the edge device (8) measuring, Collects or displays diagnostic and / or status information and implements a conversion protocol between a transmission protocol used in the field-level network and a transmission protocol used in a network at the control or operating level. Device after Claim 5 , where the transmission protocol used at the field level is the Wireless-HART protocol. Device after Claim 5 or 6 in which the operating tool (2) is a handheld, eg a smartphone, a laptop, etc.

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