FIELD OF THE DISCLOSURE

The subject matter disclosed herein relates to the field of data communications and more particularly relates to a system and method of secure communications encryption/decryption for use in a wireless communication system such as IO-Link Wireless.

BACKGROUND OF THE INVENTION

Mission critical wireless link (MCWL) communications requires wireless communications standards that ensure the highest available reliability of wireless communications (e.g., low packet error rate, minimal undetected error rates, etc.), coupled with low and bounded latency in the various protocol layers. An example of such systems are industrial and production plants that employ a large number of connected devices and require MCWL communication to produce the desired products.

Industrial systems include a variety of components, including a multitude of sensors and actuators that are implemented to execute various automated tasks in order to produce a desired product or carry out a specific process. Each individual industrial component is typically either controlled or communicated with. For example, a controlled component such as an actuator is instructed to move a robotic arm in a particular manner. A sensor, for example, is communicated with when a sensor value reading is required to adjust a process accordingly.

Historically, industrial systems used direct individual connections, such as cables running between a controller, such as a programmable logic controller (PLC), and each component of a system. This setup was costly and produced many inefficiencies as it required a multitude of controllers even for a single machine having multiple components. The control signal was transmitted using an analog or a digital signal over the individual cables. While simple in theory, such a setup requires high maintenance, high setup cost, and significant amounts of time for the configuration and setup of each component of a system.

The next evolution of automated industrial systems included a critical mission link system with a master device (i.e. the “master”) connected to a controller and configured to communicate with multiple industrial components (i.e. slaves or “devices”). The master offers a more centralized approach, with a single master connected to many components. A standardized protocol, such as the IO-Link® protocol, is an example implementation of such a system. A master is configured to connect to multiple devices, which may be easily connected to actuators, sensors, and the like. The sensors may include smart sensors that are able to provide valuable diagnostic information as well as updated status reports. The devices are configured with plug and play functionality, allowing for the seamless recognition of newly added components.

This scheme, however, retains a number of drawbacks of the previous systems, most notably the requirement of physical cables running from a controller to each component of the system. The setup of such wiring is expensive and time consuming and can be limiting in many industrial applications. For example, running cables in a sealed clean room used in many industries can be awkward and compromise the sealed nature of the room. Further, certain mobile systems that require automated vehicles, e.g., robots configured to move stock or equipment around a warehouse, would be heavily encumbered by requiring a physical cable attached to each vehicle.

With the onset of the Industry 4.0 (i.e. Industrial IoT) evolution, communication needs are changing rapidly. Machine-to-machine (M2M) communication such as connected robots, warehouse automation, and factory processing machinery are becoming more and more prevalent and demanding higher availability, better robustness, lower latency, and deterministic patterns. In this evolution, cable based communication simply cannot fulfil the requirements demanded by the tremendous increase in connected devices in terms of flexibility, mobility, and monitoring.

IO-Link is a short distance, bidirectional, digital, point-to-point, wired or wireless industrial communications networking standard (IEC 61131-9) used for connecting digital sensors and actuators to either a type of industrial fieldbus or a type of industrial Ethernet. It provides a technological platform that enables the development and use of sensors and actuators that can produce and consume enriched sets of data that in turn can be used for economically optimizing industrial automated processes and operations.

In response to these concerns, a critical mission wireless link (CMWL) system has been developed to implement a critical mission link system over wireless communication, obviating the need for cumbersome wires. The IO-Link® Wireless (IOLW) specification is an example of a critical mission link system between a master and one or more devices, and describes a time division multiplexing (TDM) uplink network configured to communicate with multiple devices.

IO-Link Wireless defines wireless network communication between sensors, actuators and controllers (PLC) in the factory automation environment. It was designed to provide a similar level of performance and backward compatible interface as with cables (IO-Link wired) so that the migration from wired to wireless systems is made easy. IO-Link Wireless provides deterministic minimal latency of 5 msec communication with 40 nodes which may be sensors or actuators. It presents reliability that is better than 10−9packet error rate (PER) in ideal cases. In comparison, other wireless standards such as WLAN, Bluetooth, and Zigbee have PERs that are six orders of magnitude less reliable (e.g., 10−3) in industrial environments.

Within networks such as IO-Link, it is necessary to ensure accurate and efficient delivery of process data, e.g., critical cycle data, between paired devices and the master, i.e. between the actuators and sensors of the system and the master. The system often operates over the 2.4 GHz industrial, scientific, and medical (ISM) radio band, which is also used for many common wireless devices, including wireless routers, monitors, cordless telephones, and the like.

The wireless communications sent over the current IO-Link Wireless implementation is not encrypted and the master and devices are not securely paired, thus opening up communications to malicious attacks. Examples of such attacks include eavesdropping, man-in-the-middle attacks, spoofing, and other hacking attempts. While many encryption services are available in general, implementing them within such a system efficiently is challenging.

Any latency introduced into the network may cause unacceptable lags in communication, which may produce errors as well as safety concerns within the industrial system controlled by the IO-Link Wireless communications. Many systems that implement such protocols require elevated security to ensure not only protection from malicious actors, but highly reliable connections to ensure the internal safety of the industrial operation is fully reliable and not compromised. Further, secure pairing between a master and one or more devices must be not only efficient, but sufficiently robust to withstand unplanned circumstances, such as maintaining pairing abilities even after a power outage or other event that disrupts communications between the master and devices.

There is a thus a need for a secure and encrypted wireless IO-Link Wireless implementation with secure pairing and secure key exchange to provide efficient and optimal performance that overcomes the problems and challenges described supra.

SUMMARY OF THE INVENTION

The present invention is a mechanism for providing security features to a wireless communications system that otherwise does not have such features. The invention is applicable in wireless communication systems such as IO-Link Wireless but is applicable to other wireless systems as well. Security features including encryption and decryption of communications, including secure key exchange, secure pairing, and secure re-pairing are provided. The security features are able to thwart several security vulnerabilities including eavesdropping, man in the middle attacks, replay, spoofing, tampering, etc.

In one embodiment, the encryption/decryption mechanism uses AES-256 block cypher with counter mode to generate blocks of cypher bits that are used to encrypt and decrypt communications between the master and devices. An optional nonce and counter value are input to the AES-256 block cypher along with a shared session key that was mutually derived on both the master and devices. Session keys are generated using a random salt and a shared permanent key (device or random key). The random salt is generated using a secure random number generator such as the well-known CSPRNG algorithms. A master key (or device key) is also used in generating session keys. Session keys are not permanent and are used to encrypt/decrypt only a finite amount of data. Once exhausted, the session key is replaced by a new one and cypher bits are generated using the new session key. A synchronized key jump procedure ensures that the master and device switch to the new session key at the same time.

The mechanism of the invention is useful to improve wireless transmission performance in industrial environments, and in particular, in IO-Link Wireless networks. The mechanisms of the present invention are particularly useful in wireless networks such those operating under the IO-Link Wireless standard. The description of the invention is provided in the context of the IO-Link Wireless standard. It is appreciated, however, that the mechanisms of the invention are applicable to other wireless networks as well.

There is thus provided in accordance with the invention, a method of secure communications between a master and a plurality of devices in a wireless communications network, the method comprising encrypting, on the master, downlink plaintext for multicast transmission to a plurality of devices over a wireless communications link utilizing a symmetric key encryption algorithm in accordance with a first counter value and a shared symmetric session key, and decrypting, on one of the devices, multicast downlink cyphertext received from the master over the wireless communications link utilizing a symmetric key decryption algorithm in accordance with a second counter value and the shared symmetric session key.

There is also provided in accordance with the invention, a method of secure communications between a plurality of devices and a master in a wireless communications network, the method comprising encrypting uplink plaintext for unicast transmission to the master over a wireless communications link utilizing a symmetric key encryption algorithm in accordance with a first counter value and a shared symmetric session key, and decrypting unicast uplink cyphertext received from one of the devices over the wireless communications link utilizing a symmetric key decryption algorithm in accordance with a second counter value and the shared symmetric session key.

There is further provided in accordance with the invention, a method of secure communications between a master and a plurality of devices in a wireless communications network, the method comprising encrypting downlink plaintext for multicast transmission to a plurality of devices over a wireless communications link utilizing a symmetric key encryption algorithm in accordance with a first counter value and a first symmetric session key, and decrypting unicast uplink cyphertext received from each device over the wireless communications link utilizing a symmetric key decryption algorithm in accordance with a second counter value and a second symmetric session key.

There is also provided in accordance with the invention, a method of secure communications between a plurality of devices and a master in a wireless communications network, the method comprising encrypting uplink plaintext for unicast transmission to the master over a wireless communications link utilizing a symmetric key encryption algorithm in accordance with a first nonce, a first counter value, and a first symmetric session key, and decrypting multicast downlink cyphertext received from the master over the wireless communications link utilizing a symmetric key decryption algorithm in accordance with a second nonce, a second counter value, and a second symmetric session key.

There is further provided in accordance with the invention, an apparatus for secure communications between a master and a plurality of devices in a wireless communications network, comprising a frequency hopping radio transmitter, a frequency hopping radio receiver, a processor coupled to and operative to control the frequency hopping radio transmitter and the frequency hopping radio receiver, the processor programmed to encrypt downlink plaintext for multicast transmission to a plurality of devices over a wireless communications link utilizing a symmetric key encryption algorithm in accordance with a first nonce, a first counter value, and a first symmetric session key, and decrypt unicast uplink cyphertext received from each device over the wireless communications link utilizing a symmetric key decryption algorithm in accordance with a second nonce, a second counter value, and a second symmetric session key.

There is also provided in accordance with the invention, an apparatus for secure communications between a plurality of devices and a master in a wireless communications network, comprising a frequency hopping radio transmitter, a frequency hopping radio receiver, a processor coupled to and operative to control the frequency hopping radio transmitter and the frequency hopping radio receiver, the processor programmed to encrypt uplink plaintext for unicast transmission to the master over a wireless communications link utilizing a symmetric key encryption algorithm in accordance with a first nonce, a first counter value, and a first symmetric session key, and decrypt multicast downlink cyphertext received from the master over the wireless communications link utilizing a symmetric key decryption algorithm in accordance with a second nonce, a second counter value, and a second symmetric session key.

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description section. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

