Method for executing a safety-critical function of a computing unit in a cyber-physical system

1. A method for executing a safety-critical function of a computing unit in a cyber-physical system, the method comprising:

receiving a request by a first computing unit in the cyber-physical system from a second computing unit, separate from the first computing unit, for an execution of the a safety-critical function at the first computing unit, the safety-critical function being a cryptographic operation;

acquiring at least one of an environment-specific measurement value and a user-specific measurement value by at least one sensor of the first computing unit, the environment-specific measurement value describing an environment of the first computing unit, the user-specific measurement value describing an interaction of a user with the first computing unit;

determining, by the first computing unit, whether the acquired at least one of the environment-specific measurement value and the user user-specific measurement value fulfills a specified criterion, wherein the specified criterion describe a specific manner in which the user interacts with the first computing unit;

in response to the determination that the values fulfills the specified criterion, executing, by the first computing unit, a physical unclonable function as the safety-critical function;

generating a cryptographic key by the physical unclonable function; and

encrypting communication between the first computing unit and second computing unit using the generated cryptographic key.

2. The method as recited in claim 1 , wherein the specified criterion describes a specific manner in which a user interacts with the first computing unit.

3. The method as recited in claim 2 , wherein the specified criterion describes at least one of: whether the user is holding the first computing unit in a hand, whether the user has physical contact with the first computing unit, whether the user is situated in a specific region around the first computing unit, and whether the user is carrying out a specific movement.

4. The method as recited in claim 1 , wherein the specified criterion describes at least one of whether the first computing unit is situated in a specific environment, whether specific further computing units stand in connection with the first computing unit, and whether specific further computing devices are situated in a specific region around the first computing unit.

5. The method as recited in claim 1 , wherein the at least one sensor includes a temperature sensor, wherein the at least one of an environment-specific measurement value and a user-specific measurement value includes a temperature of the first computing unit measured using the temperature sensor, and wherein the determining includes ascertaining whether the measured temperature exceeds a threshold value, the threshold value being exceeded only when a user is holding the first computing unit.

6. The method as recited in claim 1 , further comprising:

creating an expanded request for the execution of the safety-critical function from the received request and from the at least one of the acquired environment-specific value and the user-specific measurement value; and

executing the safety-critical function if a validity of the expanded request is recognized, the validity of the expanded request being a function of the specified criterion.

7. The method as recited in claim 6 , wherein the expanded request for the execution of the safety-critical function is created from the received request and from the at least one of the acquired environment-specific measurement value and the user-specific measurement value, and the method further comprises:

checking whether the at least one of its acquired environment-specific and the user-specific measurement value fulfills the specified criterion;

permitting the created expanded request if at least one of the acquired environment-specific measurement value and the user-specific measurement value fulfills the specified criterion; and

executing the safety-critical function if the created expanded request is permitted and if the validity of the expanded request is recognized.

8. The method as recited in claim 7 , further comprising:

acquiring at least one of a first environment-specific measurement value and a first user-specific measurement value and at least one of a second environment-specific measurement value and a second user-specific measurement value by the at least one sensor of the first computing unit;

creating the expanded request for executing the safety-critical function from the received request and from the at least one of the first acquired environment-specific measurement value and its first user-specific measurement value;

checking whether the at least one of the second acquired environment-specific measurement value and the second user-specific measurement value fulfills the specified criterion;

permitting the created expanded request if the at least one of the second acquired environment-specific and the second user-specific measurement value fulfills the specified criterion; and

executing the safety-critical function if the created expanded request is permitted and if the validity of the expanded request is recognized.

9. The method as recited in claim 1 , wherein the first computing unit wirelessly receives the request from the second computing unit using a wireless communication network.

10. The method as recited claim 1 , wherein the first computing unit is used in an Internet of things.

11. A first computing unit for executing a safety-critical function of a computing unit in a cyber-physical system, the first computing unit comprising:

an electronic microsystem; and

a plurality of sensors;

the electronic microsystem is configured to:

receive a request from a second computing unit, separate from the first computing unit, for an execution of the a safety-critical function at the first computing unit, wherein the safety-critical function is a cryptographic operation;

acquire at least one of an environment-specific measurement value and a user-specific measurement value by at least one sensor of the first computing unit, the environment-specific measurement value describing an environment of the first computing unit, the user-specific measurement value describing an interaction of a user with the first computing unit;

determine whether the acquired at least one of the environment-specific measurement value and the user user-specific measurement value fulfills a specified criterion, wherein the specified criterion describe a specific manner in which the user interacts with the first computing unit;

execute the safety-critical function based on results of the determination;

in response to the determination that the values fulfills the specified criterion, execute a physical unclonable function as the safety-critical function;

generate a cryptographic key using the physical unclonable function; and

encrypt communication between the first computing unit and second computing unit using the generated cryptographic key.

12. The first computing unit as recited in claim 11 , wherein the at least one sensor includes a temperature sensor, wherein the at least one of an environment-specific measurement value and a user-specific measurement value includes a temperature of the first computing unit measured using the temperature sensor, and wherein the determination includes ascertaining whether the measured temperature exceeds a threshold value, the threshold value being exceeded only when a user is holding the first computing unit.

13. The first computing unit as recited in claim 11 , wherein the first computing unit wirelessly receives the request from the second computing unit using a wireless communication network.

14. A non-transitory machine-readable storage medium storing a computer program for executing a safety-critical function of a first computing unit in a cyber-physical system, the computer program, when executed by the first computing unit, causing the computing unit to perform:

receiving a request by a first computing unit in the cyber-physical system from a second computing unit, separate from the first computing unit, for an execution of the a safety-critical function at the first computing unit, the safety-critical function being a cryptographic operation:

acquiring at least one of an environment-specific measurement value and a user-specific measurement value by at least one sensor of the first computing unit, the environment-specific measurement value describing an environment of the first computing unit, the user-specific measurement value describing an interaction of a user with the first computing unit;

determining, by the first computing unit, whether the acquired at least one of the environment-specific measurement value and the user user-specific measurement value fulfills a specified criterion, wherein the specified criterion describe a specific manner in which the user interacts with the first computing unit;

in response to the determination that the values fulfills the specified criterion, executing, by the first computing unit, a physical unclonable function as the safety-critical function;

generating a cryptographic key by the physical unclonable function; and

encrypting communication between the first computing unit and second computing unit using the generated cryptographic key.

15. The non-transitory machine-readable storage medium as recited in claim 14 , wherein the at least one sensor includes a temperature sensor, wherein the at least one of an environment-specific measurement value and a user-specific measurement value includes a temperature of the first computing unit measured using the temperature sensor, and wherein the determining includes ascertaining whether the measured temperature exceeds a threshold value, the threshold value being exceeded only when a user is holding the first computing unit.

16. The non-transitory machine-readable storage medium as recited in claim 14 , wherein the first computing unit wirelessly receives the request from the second computing unit using a wireless communication network.