# US 2019/0379535 A1 · Method and device for securely operating a field device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0379535 A1 - Document ID: US20190379535A1 - Status: Published application - Kind: A1 - Application number: 16/438,529 - Filed: 2019-06-12 - Published: 2019-12-12 - Earliest claimed: 2018-06-12 - Assignees: ABB Schweiz AG - Applicants: ABB Schweiz AG - Inventors: Frank Fengler - Web page: https://patentgrep.com/patent/US20190379535A1 ## CPC - G05B 19/0425: {Safety, monitoring} - H04L 9/0838: {Key agreement, i.e. key establishment technique in which a shared key is derived by parties as a function of information contributed by, or associated with, each of these (network architectures or network communication protocols for key exchange in a packet data network H04L63/061)} - G06F 21/34: involving the use of external additional devices, e.g. dongles or smart cards - G16Y 30/10: Security thereof - H04L 9/0825: {using asymmetric-key encryption or public key infrastructure [PKI], e.g. key signature or public key certificates} - H04L 9/0869: {involving random numbers or seeds} - H04L 9/0875: {based on channel impulse response [CIR]} - H04L 63/0492: {by using a location-limited connection, e.g. near-field communication or limited proximity of entities} - H04L 67/12: specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks - G05B 2219/24167: Encryption, password, user access privileges - G05B 2219/33331: Test, diagnostic of field device for correct device, correct parameters - G05B 2219/36542: Cryptography, encrypt, access, authorize with key, code, password - G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - G16Y: INFORMATION AND COMMUNICATION TECHNOLOGY SPECIALLY ADAPTED FOR THE INTERNET OF THINGS [IoT] ## Abstract A device for securely operating a field device includes: the field device, which includes at least one human-machine interface having a display device and a keyboard for operating the field device, and a communications interface for connecting a local operating device having a secure connection to a trusted server via a communications network, the secure connection being based upon an authentication feature of a local operator. The field device during use as intended does not have a secure connection to a network for process control. The field device provides and stores a query key. The field device is connected, at least logically, to the local operating device. The trusted server has a private key for providing a signed response key. The signed response key is based upon the query key. ## Claims ### Claim 1 A device for securely operating a field device, the device comprising: the field device, comprising at least one human-machine interface comprising a display device and a keyboard configured to operate the field device, and a communications interface configured to connect a local operating device having a secure connection to a trusted server via a communications network, the secure connection being based upon an authentication feature of a local operator, wherein the field device during use as intended does not have a secure connection to a network for process control, wherein the field device is configured to provide and store a query key, wherein the field device is connected, at least logically, to the local operating device, wherein the trusted server has a private key configured to provide a signed response key, and wherein the signed response key is based upon the query key. ### Claim 2 (depends on 1) The device according to claim 1, wherein the field device comprises a unique identification feature. ### Claim 3 (depends on 1) The device according to claim 1, wherein the field device comprises a random number generator. ### Claim 4 (depends on 3) The device according to claim 3, wherein the random number generator is configured to provide a random number upon request. ### Claim 5 A method for securely operating a field device having at least one human-machine interface comprising a display device and a keyboard configured to operate the field device, and a communications interface configured to connect a local operating device, wherein the field device during use as intended does not have a secure connection to a network for process control, the method comprising: connecting the field device, at least logically, to the local operating device via a local connection; establishing a secure connection between the local operating device and a trusted server using authentication features of a local operator; generating a query key in the field device; transmitting the query key via the local operating device and a secure connection to the trusted server; forming a signed response key by signing the query key with a private key of the trusted server transmitting the signed response key via the secure connection between the trusted server and the local operating device to the local operating device, and further via the local connection to the field device; extracting, in the field device, using the public key, the response key from the signed response key; comparing the response key to the query key; and enabling a predetermined procedure for authenticated unlocking of a local operation of the field device when the response key matches the query key, while maintaining an existing configuration in the field device. ### Claim 6 (depends on 5) The method according to claim 5, wherein the query key is formed from a unique identification feature of the field device and a random number. ### Claim 7 (depends on 5) The method according to claim 5, wherein authorization of the operator for unlocking the field device is checked using the trusted server. ### Claim 8 (depends on 5) The method according to claim 5, wherein validity of the query key is checked using the trusted server.