Patent Publication Number: US-10776080-B2

Title: Integrated development tool for an internet of things (IOT) system

Description:
BACKGROUND 
     Field of the Invention 
     This invention relates generally to the field of computer systems. More particularly, the invention relates to an integrated development tool for an Internet of Things (IoT) system. 
     Description of the Related Art 
     The “Internet of Things” refers to the interconnection of uniquely-identifiable embedded devices within the Internet infrastructure. Ultimately, IoT is expected to result in new, wide-ranging types of applications in which virtually any type of physical thing may provide information about itself or its surroundings and/or may be controlled remotely via client devices over the Internet. 
     IoT development and adoption has been slow due to issues related to connectivity, power, and a lack of standardization. For example, one obstacle to IoT development and adoption is that no standard platform exists to allow developers to design and offer new IoT devices and services. In order enter into the IoT market, a developer must design the entire IoT platform from the ground up, including the network protocols and infrastructure, hardware, software and services required to support the desired IoT implementation. As a result, each provider of IoT devices uses proprietary techniques for designing and connecting the IoT devices, making the adoption of multiple types of IoT devices burdensome for end users. Another obstacle to IoT adoption is the difficulty associated with connecting and powering IoT devices. Connecting appliances such as refrigerators, garage door openers, environmental sensors, home security sensors/controllers, etc, for example, requires an electrical source to power each connected IoT device, and such an electrical source is often not conveniently located. 
     In addition, IoT development has been slow due to the lack of integrated development tools. For example, developers must independently design code and hardware for each individual IoT device and for each IoT service, resulting in inefficiencies in the design process. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A better understanding of the present invention can be obtained from the following detailed description in conjunction with the following drawings, in which: 
         FIGS. 1A-B  illustrates different embodiments of an IoT system architecture; 
         FIG. 2  illustrates an IoT device in accordance with one embodiment of the invention; 
         FIG. 3  illustrates an IoT hub in accordance with one embodiment of the invention; 
         FIG. 4A-B  illustrate embodiments of the invention for controlling and collecting data from IoT devices, and generating notifications; 
         FIG. 5  illustrates embodiments of the invention for collecting data from IoT devices and generating notifications from an IoT hub and/or IoT service; 
         FIG. 6  illustrates one embodiment of a system in which an intermediary mobile device collects data from a stationary IoT device and provides the data to an IoT hub; 
         FIG. 7  illustrates intermediary connection logic implemented in one embodiment of the invention; 
         FIG. 8  illustrates a method in accordance with one embodiment of the invention; 
         FIG. 9A  illustrates an embodiment in which program code and data updates are provided to the IoT device; 
         FIG. 9B  illustrates an embodiment of a method in which program code and data updates are provided to the IoT device; 
         FIG. 10  illustrates a high level view of one embodiment of a security architecture; 
         FIG. 11  illustrates one embodiment of an architecture in which a subscriber identity module (SIM) is used to store keys on IoT devices; 
         FIG. 12A  illustrates one embodiment in which IoT devices are registered using barcodes or QR codes; 
         FIG. 12B  illustrates one embodiment in which pairing is performed using barcodes or QR codes; 
         FIG. 13  illustrates one embodiment of a method for programming a SIM using an IoT hub; 
         FIG. 14  illustrates one embodiment of a method for registering an IoT device with an IoT hub and IoT service; and 
         FIG. 15  illustrates one embodiment of a method for encrypting data to be transmitted to an IoT device; 
         FIGS. 16A-B  illustrate different embodiments of the invention for encrypting data between an IoT service and an IoT device; 
         FIG. 17  illustrates embodiments of the invention for performing a secure key exchange, generating a common secret, and using the secret to generate a key stream; 
         FIG. 18  illustrates a packet structure in accordance with one embodiment of the invention; 
         FIG. 19  illustrates techniques employed in one embodiment for writing and reading data to/from an IoT device without formally pairing with the IoT device; 
         FIG. 20  illustrates an exemplary set of command packets employed in one embodiment of the invention; 
         FIG. 21  illustrates an exemplary sequence of transactions using command packets; 
         FIG. 22  illustrates a method in accordance with one embodiment of the invention; and 
         FIG. 23A-C  illustrates a method for secure pairing in accordance with one embodiment of the invention; 
         FIG. 24  illustrates one embodiment of an interface between a microcontroller unit and a secure communication module; 
         FIG. 25  illustrates additional details for an embodiment of an interface between a microcontroller unit and a secure communication module; and 
         FIG. 26  illustrates a communication format employed in one embodiment of the invention. 
         FIG. 27  illustrates one embodiment of an integrated development tool 
         FIG. 28  illustrates one embodiment of a method implemented by an integrated development tool. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the invention described below. It will be apparent, however, to one skilled in the art that the embodiments of the invention may be practiced without some of these specific details. In other instances, well-known structures and devices are shown in block diagram form to avoid obscuring the underlying principles of the embodiments of the invention. 
     One embodiment of the invention comprises an Internet of Things (IoT) platform which may be utilized by developers to design and build new IoT devices and applications. In particular, one embodiment includes a base hardware/software platform for IoT devices including a predefined networking protocol stack and an IoT hub through which the IoT devices are coupled to the Internet. In addition, one embodiment includes an IoT service through which the IoT hubs and connected IoT devices may be accessed and managed as described below. In addition, one embodiment of the IoT platform includes an IoT app or Web application (e.g., executed on a client device) to access and configured the IoT service, hub and connected devices. Existing online retailers and other Website operators may leverage the IoT platform described herein to readily provide unique IoT functionality to existing user bases. 
       FIG. 1A  illustrates an overview of an architectural platform on which embodiments of the invention may be implemented. In particular, the illustrated embodiment includes a plurality of IoT devices  101 - 105  communicatively coupled over local communication channels  130  to a central IoT hub  110  which is itself communicatively coupled to an IoT service  120  over the Internet  220 . Each of the IoT devices  101 - 105  may initially be paired to the IoT hub  110  (e.g., using the pairing techniques described below) in order to enable each of the local communication channels  130 . In one embodiment, the IoT service  120  includes an end user database  122  for maintaining user account information and data collected from each user&#39;s IoT devices. For example, if the IoT devices include sensors (e.g., temperature sensors, accelerometers, heat sensors, motion detectore, etc), the database  122  may be continually updated to store the data collected by the IoT devices  101 - 105 . The data stored in the database  122  may then be made accessible to the end user via the IoT app or browser installed on the user&#39;s device  135  (or via a desktop or other client computer system) and to web clients (e.g., such as websites  130  subscribing to the IoT service  120 ). 
     The IoT devices  101 - 105  may be equipped with various types of sensors to collect information about themselves and their surroundings and provide the collected information to the IoT service  120 , user devices  135  and/or external Websites  130  via the IoT hub  110 . Some of the IoT devices  101 - 105  may perform a specified function in response to control commands sent through the IoT hub  110 . Various specific examples of information collected by the IoT devices  101 - 105  and control commands are provided below. In one embodiment described below, the IoT device  101  is a user input device designed to record user selections and send the user selections to the IoT service  120  and/or Website. 
     In one embodiment, the IoT hub  110  includes a cellular radio to establish a connection to the Internet  220  via a cellular service  115  such as a 4G (e.g., Mobile WiMAX, LTE) or 5G cellular data service. Alternatively, or in addition, the IoT hub  110  may include a WiFi radio to establish a WiFi connection through a WiFi access point or router  116  which couples the IoT hub  110  to the Internet (e.g., via an Internet Service Provider providing Internet service to the end user). Of course, it should be noted that the underlying principles of the invention are not limited to any particular type of communication channel or protocol. 
     In one embodiment, the IoT devices  101 - 105  are ultra low-power devices capable of operating for extended periods of time on battery power (e.g., years). To conserve power, the local communication channels  130  may be implemented using a low-power wireless communication technology such as Bluetooth Low Energy (LE). In this embodiment, each of the IoT devices  101 - 105  and the IoT hub  110  are equipped with Bluetooth LE radios and protocol stacks. 
     As mentioned, in one embodiment, the IoT platform includes an IoT app or Web application executed on user devices  135  to allow users to access and configure the connected IoT devices  101 - 105 , IoT hub  110 , and/or IoT service  120 . In one embodiment, the app or web application may be designed by the operator of a Website  130  to provide IoT functionality to its user base. As illustrated, the Website may maintain a user database  131  containing account records related to each user. 
       FIG. 1B  illustrates additional connection options for a plurality of IoT hubs  110 - 111 ,  190  In this embodiment a single user may have multiple hubs  110 - 111  installed onsite at a single user premises  180  (e.g., the user&#39;s home or business). This may be done, for example, to extend the wireless range needed to connect all of the IoT devices  101 - 105 . As indicated, if a user has multiple hubs  110 ,  111  they may be connected via a local communication channel (e.g., Wifi, Ethernet, Power Line Networking, etc). In one embodiment, each of the hubs  110 - 111  may establish a direct connection to the IoT service  120  through a cellular  115  or WiFi  116  connection (not explicitly shown in  FIG. 1B ). Alternatively, or in addition, one of the IoT hubs such as IoT hub  110  may act as a “master” hub which provides connectivity and/or local services to all of the other IoT hubs on the user premises  180 , such as IoT hub  111  (as indicated by the dotted line connecting IoT hub  110  and IoT hub  111 ). For example, the master IoT hub  110  may be the only IoT hub to establish a direct connection to the IoT service  120 . In one embodiment, only the “master” IoT hub  110  is equipped with a cellular communication interface to establish the connection to the IoT service  120 . As such, all communication between the IoT service  120  and the other IoT hubs  111  will flow through the master IoT hub  110 . In this role, the master IoT hub  110  may be provided with additional program code to perform filtering operations on the data exchanged between the other IoT hubs  111  and IoT service  120  (e.g., servicing some data requests locally when possible). 
     Regardless of how the IoT hubs  110 - 111  are connected, in one embodiment, the IoT service  120  will logically associate the hubs with the user and combine all of the attached IoT devices  101 - 105  under a single comprehensive user interface, accessible via a user device with the installed app  135  (and/or a browser-based interface). 
     In this embodiment, the master IoT hub  110  and one or more slave IoT hubs  111  may connect over a local network which may be a WiFi network  116 , an Ethernet network, and/or a using power-line communications (PLC) networking (e.g., where all or portions of the network are run through the user&#39;s power lines). In addition, to the IoT hubs  110 - 111 , each of the IoT devices  101 - 105  may be interconnected with the IoT hubs  110 - 111  using any type of local network channel such as WiFi, Ethernet, PLC, or Bluetooth LE, to name a few. 
       FIG. 1B  also shows an IoT hub  190  installed at a second user premises  181 . A virtually unlimited number of such IoT hubs  190  may be installed and configured to collect data from IoT devices  191 - 192  at user premises around the world. In one embodiment, the two user premises  180 - 181  may be configured for the same user. For example, one user premises  180  may be the user&#39;s primary home and the other user premises  181  may be the user&#39;s vacation home. In such a case, the IoT service  120  will logically associate the IoT hubs  110 - 111 ,  190  with the user and combine all of the attached IoT devices  101 - 105 ,  191 - 192  under a single comprehensive user interface, accessible via a user device with the installed app  135  (and/or a browser-based interface). 
     As illustrated in  FIG. 2 , an exemplary embodiment of an IoT device  101  includes a memory  210  for storing program code and data  201 - 203  and a low power microcontroller  200  for executing the program code and processing the data. The memory  210  may be a volatile memory such as dynamic random access memory (DRAM) or may be a non-volatile memory such as Flash memory. In one embodiment, a non-volatile memory may be used for persistent storage and a volatile memory may be used for execution of the program code and data at runtime. Moreover, the memory  210  may be integrated within the low power microcontroller  200  or may be coupled to the low power microcontroller  200  via a bus or communication fabric. The underlying principles of the invention are not limited to any particular implementation of the memory  210 . 
     As illustrated, the program code may include application program code  203  defining an application-specific set of functions to be performed by the IoT device  201  and library code  202  comprising a set of predefined building blocks which may be utilized by the application developer of the IoT device  101 . In one embodiment, the library code  202  comprises a set of basic functions required to implement an IoT device such as a communication protocol stack  201  for enabling communication between each IoT device  101  and the IoT hub  110 . As mentioned, in one embodiment, the communication protocol stack  201  comprises a Bluetooth LE protocol stack. In this embodiment, Bluetooth LE radio and antenna  207  may be integrated within the low power microcontroller  200 . However, the underlying principles of the invention are not limited to any particular communication protocol. 
     The particular embodiment shown in  FIG. 2  also includes a plurality of input devices or sensors  210  to receive user input and provide the user input to the low power microcontroller, which processes the user input in accordance with the application code  203  and library code  202 . In one embodiment, each of the input devices include an LED  209  to provide feedback to the end user. 
     In addition, the illustrated embodiment includes a battery  208  for supplying power to the low power microcontroller. In one embodiment, a non-chargeable coin cell battery is used. However, in an alternate embodiment, an integrated rechargeable battery may be used (e.g., rechargeable by connecting the IoT device to an AC power supply (not shown)). 
     A speaker  205  is also provided for generating audio. In one embodiment, the low power microcontroller  299  includes audio decoding logic for decoding a compressed audio stream (e.g., such as an MPEG-4/Advanced Audio Coding (AAC) stream) to generate audio on the speaker  205 . Alternatively, the low power microcontroller  200  and/or the application code/data  203  may include digitally sampled snippets of audio to provide verbal feedback to the end user as the user enters selections via the input devices  210 . 
     In one embodiment, one or more other/alternate I/O devices or sensors  250  may be included on the IoT device  101  based on the particular application for which the IoT device  101  is designed. For example, an environmental sensor may be included to measure temperature, pressure, humidity, etc. A security sensor and/or door lock opener may be included if the IoT device is used as a security device. Of course, these examples are provided merely for the purposes of illustration. The underlying principles of the invention are not limited to any particular type of IoT device. In fact, given the highly programmable nature of the low power microcontroller  200  equipped with the library code  202 , an application developer may readily develop new application code  203  and new I/O devices  250  to interface with the low power microcontroller for virtually any type of IoT application. 
     In one embodiment, the low power microcontroller  200  also includes a secure key store for storing encryption keys for encrypting communications and/or generating signatures. Alternatively, the keys may be secured in a subscriber identify module (SIM). 
     A wakeup receiver  207  is included in one embodiment to wake the IoT device from an ultra low power state in which it is consuming virtually no power. In one embodiment, the wakeup receiver  207  is configured to cause the IoT device  101  to exit this low power state in response to a wakeup signal received from a wakeup transmitter  307  configured on the IoT hub  110  as shown in  FIG. 3 . In particular, in one embodiment, the transmitter  307  and receiver  207  together form an electrical resonant transformer circuit such as a Tesla coil. In operation, energy is transmitted via radio frequency signals from the transmitter  307  to the receiver  207  when the hub  110  needs to wake the IoT device  101  from a very low power state. Because of the energy transfer, the IoT device  101  may be configured to consume virtually no power when it is in its low power state because it does not need to continually “listen” for a signal from the hub (as is the case with network protocols which allow devices to be awakened via a network signal). Rather, the microcontroller  200  of the IoT device  101  may be configured to wake up after being effectively powered down by using the energy electrically transmitted from the transmitter  307  to the receiver  207 . 
     As illustrated in  FIG. 3 , the IoT hub  110  also includes a memory  317  for storing program code and data  305  and hardware logic  301  such as a microcontroller for executing the program code and processing the data. A wide area network (WAN) interface  302  and antenna  310  couple the IoT hub  110  to the cellular service  115 . Alternatively, as mentioned above, the IoT hub  110  may also include a local network interface (not shown) such as a WiFi interface (and WiFi antenna) or Ethernet interface for establishing a local area network communication channel. In one embodiment, the hardware logic  301  also includes a secure key store for storing encryption keys for encrypting communications and generating/verifying signatures. Alternatively, the keys may be secured in a subscriber identify module (SIM). 
     A local communication interface  303  and antenna  311  establishes local communication channels with each of the IoT devices  101 - 105 . As mentioned above, in one embodiment, the local communication interface  303 /antenna  311  implements the Bluetooth LE standard. However, the underlying principles of the invention are not limited to any particular protocols for establishing the local communication channels with the IoT devices  101 - 105 . Although illustrated as separate units in  FIG. 3 , the WAN interface  302  and/or local communication interface  303  may be embedded within the same chip as the hardware logic  301 . 
     In one embodiment, the program code and data includes a communication protocol stack  308  which may include separate stacks for communicating over the local communication interface  303  and the WAN interface  302 . In addition, device pairing program code and data  306  may be stored in the memory to allow the IoT hub to pair with new IoT devices. In one embodiment, each new IoT device  101 - 105  is assigned a unique code which is communicated to the IoT hub  110  during the pairing process. For example, the unique code may be embedded in a barcode on the IoT device and may be read by the barcode reader  106  or may be communicated over the local communication channel  130 . In an alternate embodiment, the unique ID code is embedded magnetically on the IoT device and the IoT hub has a magnetic sensor such as an radio frequency ID (RFID) or near field communication (NFC) sensor to detect the code when the IoT device  101  is moved within a few inches of the IoT hub  110 . 
     In one embodiment, once the unique ID has been communicated, the IoT hub  110  may verify the unique ID by querying a local database (not shown), performing a hash to verify that the code is acceptable, and/or communicating with the IoT service  120 , user device  135  and/or Website  130  to validate the ID code. Once validated, in one embodiment, the IoT hub  110  pairs the IoT device  101  and stores the pairing data in memory  317  (which, as mentioned, may include non-volatile memory). Once pairing is complete, the IoT hub  110  may connect with the IoT device  101  to perform the various IoT functions described herein. 
     In one embodiment, the organization running the IoT service  120  may provide the IoT hub  110  and a basic hardware/software platform to allow developers to easily design new IoT services. In particular, in addition to the IoT hub  110 , developers may be provided with a software development kit (SDK) to update the program code and data  305  executed within the hub  110 . In addition, for IoT devices  101 , the SDK may include an extensive set of library code  202  designed for the base IoT hardware (e.g., the low power microcontroller  200  and other components shown in  FIG. 2 ) to facilitate the design of various different types of applications  101 . In one embodiment, the SDK includes a graphical design interface in which the developer needs only to specify input and outputs for the IoT device. All of the networking code, including the communication stack  201  that allows the IoT device  101  to connect to the hub  110  and the service  120 , is already in place for the developer. In addition, in one embodiment, the SDK also includes a library code base to facilitate the design of apps for mobile devices (e.g., iPhone and Android devices). 
     In one embodiment, the IoT hub  110  manages a continuous bi-directional stream of data between the IoT devices  101 - 105  and the IoT service  120 . In circumstances where updates to/from the IoT devices  101 - 105  are required in real time (e.g., where a user needs to view the current status of security devices or environmental readings), the IoT hub may maintain an open TCP socket to provide regular updates to the user device  135  and/or external Websites  130 . The specific networking protocol used to provide updates may be tweaked based on the needs of the underlying application. For example, in some cases, where may not make sense to have a continuous bi-directional stream, a simple request/response protocol may be used to gather information when needed. 
     In one embodiment, both the IoT hub  110  and the IoT devices  101 - 105  are automatically upgradeable over the network. In particular, when a new update is available for the IoT hub  110  it may automatically download and install the update from the IoT service  120 . It may first copy the updated code into a local memory, run and verify the update before swapping out the older program code. Similarly, when updates are available for each of the IoT devices  101 - 105 , they may initially be downloaded by the IoT hub  110  and pushed out to each of the IoT devices  101 - 105 . Each IoT device  101 - 105  may then apply the update in a similar manner as described above for the IoT hub and report back the results of the update to the IoT hub  110 . If the update is successful, then the IoT hub  110  may delete the update from its memory and record the latest version of code installed on each IoT device (e.g., so that it may continue to check for new updates for each IoT device). 
     In one embodiment, the IoT hub  110  is powered via A/C power. In particular, the IoT hub  110  may include a power unit  390  with a transformer for transforming A/C voltage supplied via an A/C power cord to a lower DC voltage. 
       FIG. 4A  illustrates one embodiment of the invention for performing universal remote control operations using the IoT system. In particular, in this embodiment, a set of IoT devices  101 - 103  are equipped with infrared (IR) and/or radio frequency (RF) blasters  401 - 403 , respectively, for transmitting remote control codes to control various different types of electronics equipment including air conditioners/heaters  430 , lighting systems  431 , and audiovisual equipment  432  (to name just a few). In the embodiment shown in  FIG. 4A , the IoT devices  101 - 103  are also equipped with sensors  404 - 406 , respectively, for detecting the operation of the devices which they control, as described below. 
     For example, sensor  404  in IoT device  101  may be a temperature and/or humidity sensor for sensing the current temperature/humidity and responsively controlling the air conditioner/heater  430  based on a current desired temperature. In this embodiment, the air conditioner/heater  430  is one which is designed to be controlled via a remote control device (typically a remote control which itself has a temperature sensor embedded therein). In one embodiment, the user provides the desired temperature to the IoT hub  110  via an app or browser installed on a user device  135 . Control logic  412  executed on the IoT hub  110  receives the current temperature/humidity data from the sensor  404  and responsively transmits commands to the IoT device  101  to control the IR/RF blaster  401  in accordance with the desired temperature/humidity. For example, if the temperature is below the desired temperature, then the control logic  412  may transmit a command to the air conditioner/heater via the IR/RF blaster  401  to increase the temperature (e.g., either by turning off the air conditioner or turning on the heater). The command may include the necessary remote control code stored in a database  413  on the IoT hub  110 . Alternatively, or in addition, the IoT service  421  may implement control logic  421  to control the electronics equipment  430 - 432  based on specified user preferences and stored control codes  422 . 
     IoT device  102  in the illustrated example is used to control lighting  431 . In particular, sensor  405  in IoT device  102  may photosensor or photodetector configured to detect the current brightness of the light being produced by a light fixture  431  (or other lighting apparatus). The user may specify a desired lighting level (including an indication of ON or OFF) to the IoT hub  110  via the user device  135 . In response, the control logic  412  will transmit commands to the IR/RF blaster  402  to control the current brightness level of the lights  431  (e.g., increasing the lighting if the current brightness is too low or decreasing the lighting if the current brightness is too high; or simply turning the lights ON or OFF). 
     IoT device  103  in the illustrated example is configured to control audiovisual equipment  432  (e.g., a television, A/V receiver, cable/satellite receiver, AppleTV™, etc). Sensor  406  in IoT device  103  may be an audio sensor (e.g., a microphone and associated logic) for detecting a current ambient volume level and/or a photosensor to detect whether a television is on or off based on the light generated by the television (e.g., by measuring the light within a specified spectrum). Alternatively, sensor  406  may include a temperature sensor connected to the audiovisual equipment to detect whether the audio equipment is on or off based on the detected temperature. Once again, in response to user input via the user device  135 , the control logic  412  may transmit commands to the audiovisual equipment via the IR blaster  403  of the IoT device  103 . 
     It should be noted that the foregoing are merely illustrative examples of one embodiment of the invention. The underlying principles of the invention are not limited to any particular type of sensors or equipment to be controlled by IoT devices. 
     In an embodiment in which the IoT devices  101 - 103  are coupled to the IoT hub  110  via a Bluetooth LE connection, the sensor data and commands are sent over the Bluetooth LE channel. However, the underlying principles of the invention are not limited to Bluetooth LE or any other communication standard. 
     In one embodiment, the control codes required to control each of the pieces of electronics equipment are stored in a database  413  on the IoT hub  110  and/or a database  422  on the IoT service  120 . As illustrated in  FIG. 4B , the control codes may be provided to the IoT hub  110  from a master database of control codes  422  for different pieces of equipment maintained on the IoT service  120 . The end user may specify the types of electronic (or other) equipment to be controlled via the app or browser executed on the user device  135  and, in response, a remote control code learning module  491  on the IoT hub may retrieve the required IR/RF codes from the remote control code database  492  on the IoT service  120  (e.g., identifying each piece of electronic equipment with a unique ID). 
     In addition, in one embodiment, the IoT hub  110  is equipped with an IR/RF interface  490  to allow the remote control code learning module  491  to “learn” new remote control codes directly from the original remote control  495  provided with the electronic equipment. For example, if control codes for the original remote control provided with the air conditioner  430  is not included in the remote control database, the user may interact with the IoT hub  110  via the app/browser on the user device  135  to teach the IoT hub  110  the various control codes generated by the original remote control (e.g., increase temperature, decrease temperature, etc). Once the remote control codes are learned they may be stored in the control code database  413  on the IoT hub  110  and/or sent back to the IoT service  120  to be included in the central remote control code database  492  (and subsequently used by other users with the same air conditioner unit  430 ). 
     In one embodiment, each of the IoT devices  101 - 103  have an extremely small form factor and may be affixed on or near their respective electronics equipment  430 - 432  using double-sided tape, a small nail, a magnetic attachment, etc. For control of a piece of equipment such as the air conditioner  430 , it would be desirable to place the IoT device  101  sufficiently far away so that the sensor  404  can accurately measure the ambient temperature in the home (e.g., placing the IoT device directly on the air conditioner would result in a temperature measurement which would be too low when the air conditioner was running or too high when the heater was running). In contrast, the IoT device  102  used for controlling lighting may be placed on or near the lighting fixture  431  for the sensor  405  to detect the current lighting level. 
     In addition to providing general control functions as described, one embodiment of the IoT hub  110  and/or IoT service  120  transmits notifications to the end user related to the current status of each piece of electronics equipment. The notifications, which may be text messages and/or app-specific notifications, may then be displayed on the display of the user&#39;s mobile device  135 . For example, if the user&#39;s air conditioner has been on for an extended period of time but the temperature has not changed, the IoT hub  110  and/or IoT service  120  may send the user a notification that the air conditioner is not functioning properly. If the user is not home (which may be detected via motion sensors or based on the user&#39;s current detected location), and the sensors  406  indicate that audiovisual equipment  430  is on or sensors  405  indicate that the lights are on, then a notification may be sent to the user, asking if the user would like to turn off the audiovisual equipment  432  and/or lights  431 . The same type of notification may be sent for any equipment type. 
     Once the user receives a notification, he/she may remotely control the electronics equipment  430 - 432  via the app or browser on the user device  135 . In one embodiment, the user device  135  is a touchscreen device and the app or browser displays an image of a remote control with user-selectable buttons for controlling the equipment  430 - 432 . Upon receiving a notification, the user may open the graphical remote control and turn off or adjust the various different pieces of equipment. If connected via the IoT service  120 , the user&#39;s selections may be forwarded from the IoT service  120  to the IoT hub  110  which will then control the equipment via the control logic  412 . Alternatively, the user input may be sent directly to the IoT hub  110  from the user device  135 . 
     In one embodiment, the user may program the control logic  412  on the IoT hub  110  to perform various automatic control functions with respect to the electronics equipment  430 - 432 . In addition to maintaining a desired temperature, brightness level, and volume level as described above, the control logic  412  may automatically turn off the electronics equipment if certain conditions are detected. For example, if the control logic  412  detects that the user is not home and that the air conditioner is not functioning, it may automatically turn off the air conditioner. Similarly, if the user is not home, and the sensors  406  indicate that audiovisual equipment  430  is on or sensors  405  indicate that the lights are on, then the control logic  412  may automatically transmit commands via the IR/RF blasters  403  and  402 , to turn off the audiovisual equipment and lights, respectively. 
       FIG. 5  illustrates additional embodiments of IoT devices  104 - 105  equipped with sensors  503 - 504  for monitoring electronic equipment  530 - 531 . In particular, the IoT device  104  of this embodiment includes a temperature sensor  503  which may be placed on or near a stove  530  to detect when the stove has been left on. In one embodiment, the IoT device  104  transmits the current temperature measured by the temperature sensor  503  to the IoT hub  110  and/or the IoT service  120 . If the stove is detected to be on for more than a threshold time period (e.g., based on the measured temperature), then control logic  512  may transmit a notification to the end user&#39;s device  135  informing the user that the stove  530  is on. In addition, in one embodiment, the IoT device  104  may include a control module  501  to turn off the stove, either in response to receiving an instruction from the user or automatically (if the control logic  512  is programmed to do so by the user). In one embodiment, the control logic  501  comprises a switch to cut off electricity or gas to the stove  530 . However, in other embodiments, the control logic  501  may be integrated within the stove itself. 
       FIG. 5  also illustrates an IoT device  105  with a motion sensor  504  for detecting the motion of certain types of electronics equipment such as a washer and/or dryer. Another sensor that may be used is an audio sensor (e.g., microphone and logic) for detecting an ambient volume level. As with the other embodiments described above, this embodiment may transmit notifications to the end user if certain specified conditions are met (e.g., if motion is detected for an extended period of time, indicating that the washer/dryer are not turning off). Although not shown in  FIG. 5 , IoT device  105  may also be equipped with a control module to turn off the washer/dryer  531  (e.g., by switching off electric/gas), automatically, and/or in response to user input. 
     In one embodiment, a first IoT device with control logic and a switch may be configured to turn off all power in the user&#39;s home and a second IoT device with control logic and a switch may be configured to turn off all gas in the user&#39;s home. IoT devices with sensors may then be positioned on or near electronic or gas-powered equipment in the user&#39;s home. If the user is notified that a particular piece of equipment has been left on (e.g., the stove  530 ), the user may then send a command to turn off all electricity or gas in the home to prevent damage. Alternatively, the control logic  512  in the IoT hub  110  and/or the IoT service  120  may be configured to automatically turn off electricity or gas in such situations. 
     In one embodiment, the IoT hub  110  and IoT service  120  communicate at periodic intervals. If the IoT service  120  detects that the connection to the IoT hub  110  has been lost (e.g., by failing to receive a request or response from the IoT hub for a specified duration), it will communicate this information to the end user&#39;s device  135  (e.g., by sending a text message or app-specific notification). 
     Apparatus and Method for Communicating Data Through an Intermediary Device 
     As mentioned above, because the wireless technologies used to interconnect IoT devices such as Bluetooth LE are generally short range technologies, if the hub for an IoT implementation is outside the range of an IoT device, the IoT device will not be able to transmit data to the IoT hub (and vice versa). 
     To address this deficiency, one embodiment of the invention provides a mechanism for an IoT device which is outside of the wireless range of the IoT hub to periodically connect with one or more mobile devices when the mobile devices are within range. Once connected, the IoT device can transmit any data which needs to be provided to the IoT hub to the mobile device which then forwards the data to the IoT hub. 
     As illustrated in  FIG. 6  one embodiment includes an IoT hub  110 , an IoT device  601  which is out of range of the IoT hub  110  and a mobile device  611 . The out of range IoT device  601  may include any form of IoT device capable of collecting and communicating data. For example, the IoT device  601  may comprise a data collection device configured within a refrigerator to monitor the food items available in the refrigerator, the users who consume the food items, and the current temperature. Of course, the underlying principles of the invention are not limited to any particular type of IoT device. The techniques described herein may be implemented using any type of IoT device including those used to collect and transmit data for smart meters, stoves, washers, dryers, lighting systems, HVAC systems, and audiovisual equipment, to name just a few. 
     Moreover, the mobile device In operation, the IoT device  611  illustrated in  FIG. 6  may be any form of mobile device capable of communicating and storing data. For example, in one embodiment, the mobile device  611  is a smartphone with an app installed thereon to facilitate the techniques described herein. In another embodiment, the mobile device  611  comprises a wearable device such as a communication token affixed to a neckless or bracelet, a smartwatch or a fitness device. The wearable token may be particularly useful for elderly users or other users who do not own a smartphone device. 
     In operation, the out of range IoT device  601  may periodically or continually check for connectivity with a mobile device  611 . Upon establishing a connection (e.g., as the result of the user moving within the vicinity of the refrigerator) any collected data  605  on the IoT device  601  is automatically transmitted to a temporary data repository  615  on the mobile device  611 . In one embodiment, the IoT device  601  and mobile device  611  establish a local wireless communication channel using a low power wireless standard such as BTLE. In such a case, the mobile device  611  may initially be paired with the IoT device  601  using known pairing techniques. 
     One the data has been transferred to the temporary data repository, the mobile device  611  will transmit the data once communication is established with the IoT hub  110  (e.g., when the user walks within the range of the IoT hub  110 ). The IoT hub may then store the data in a central data repository  413  and/or send the data over the Internet to one or more services and/or other user devices. In one embodiment, the mobile device  611  may use a different type of communication channel to provide the data to the IoT hub  110  (potentially a higher power communication channel such as WiFi). 
     The out of range IoT device  601 , the mobile device  611 , and the IoT hub may all be configured with program code and/or logic to implement the techniques described herein. As illustrated in  FIG. 7 , for example, the IoT device  601  may be configured with intermediary connection logic and/or application, the mobile device  611  may be configured with an intermediary connection logic/application, and the IoT hub  110  may be configured with an intermediary connection logic/application  721  to perform the operations described herein. The intermediary connection logic/application on each device may be implemented in hardware, software, or any combination thereof. In one embodiment, the intermediary connection logic/application  701  of the IoT device  601  searches and establishes a connection with the intermediary connection logic/application  711  on the mobile device (which may be implemented as a device app) to transfer the data to the temporary data repository  615 . The intermediary connection logic/application  701  on the mobile device  611  then forwards the data to the intermediary connection logic/application on the IoT hub, which stores the data in the central data repository  413 . 
     As illustrated in  FIG. 7 , the intermediary connection logic/applications  701 ,  711 ,  721 , on each device may be configured based on the application at hand. For example, for a refrigerator, the connection logic/application  701  may only need to transmit a few packets on a periodic basis. For other applications (e.g., temperature sensors), the connection logic/application  701  may need to transmit more frequent updates. 
     Rather than a mobile device  611 , in one embodiment, the IoT device  601  may be configured to establish a wireless connection with one or more intermediary IoT devices, which are located within range of the IoT hub  110 . In this embodiment, any IoT devices  601  out of range of the IoT hub may be linked to the hub by forming a “chain” using other IoT devices. 
     In addition, while only a single mobile device  611  is illustrated in  FIGS. 6-7  for simplicity, in one embodiment, multiple such mobile devices of different users may be configured to communicate with the IoT device  601 . Moreover, the same techniques may be implemented for multiple other IoT devices, thereby forming an intermediary device data collection system across the entire home. 
     Moreover, in one embodiment, the techniques described herein may be used to collect various different types of pertinent data. For example, in one embodiment, each time the mobile device  611  connects with the IoT device  601 , the identity of the user may be included with the collected data  605 . In this manner, the IoT system may be used to track the behavior of different users within the home. For example, if used within a refrigerator, the collected data  605  may then include the identify of each user who passes by fridge, each user who opens the fridge, and the specific food items consumed by each user. Different types of data may be collected from other types of IoT devices. Using this data the system is able to determine, for example, which user washes clothes, which user watches TV on a given day, the times at which each user goes to sleep and wakes up, etc. All of this crowd-sourced data may then be compiled within the data repository  413  of the IoT hub and/or forwarded to an external service or user. 
     Another beneficial application of the techniques described herein is for monitoring elderly users who may need assistance. For this application, the mobile device  611  may be a very small token worn by the elderly user to collect the information in different rooms of the user&#39;s home. Each time the user opens the refrigerator, for example, this data will be included with the collected data  605  and transferred to the IoT hub  110  via the token. The IoT hub may then provide the data to one or more external users (e.g., the children or other individuals who care for the elderly user). If data has not been collected for a specified period of time (e.g., 12 hours), then this means that the elderly user has not been moving around the home and/or has not been opening the refrigerator. The IoT hub  110  or an external service connected to the IoT hub may then transmit an alert notification to these other individuals, informing them that they should check on the elderly user. In addition, the collected data  605  may include other pertinent information such as the food being consumed by the user and whether a trip to the grocery store is needed, whether and how frequently the elderly user is watching TV, the frequency with which the elderly user washes clothes, etc. 
     In another implementation, the if there is a problem with an electronic device such as a washer, refrigerator, HVAC system, etc, the collected data may include an indication of a part that needs to be replaced. In such a case, a notification may be sent to a technician with a request to fix the problem. The technician may then arrive at the home with the needed replacement part. 
     A method in accordance with one embodiment of the invention is illustrated in  FIG. 8 . The method may be implemented within the context of the architectures described above, but is not limited to any particular architecture. 
     At  801 , an IoT device which is out of range of the IoT hub periodically collects data (e.g., opening of the refrigerator door, food items used, etc). At  802  the IoT device periodically or continually checks for connectivity with a mobile device (e.g., using standard local wireless techniques for establishing a connection such as those specified by the BTLE standard). If the connection to the mobile device is established, determined at  802 , then at  803 , the collected data is transferred to the mobile device at  803 . At  804 , the mobile device transfers the data to the IoT hub, an external service and/or a user. As mentioned, the mobile device may transmit the data immediately if it is already connected (e.g., via a WiFi link). 
     In addition to collecting data from IoT devices, in one embodiment, the techniques described herein may be used to update or otherwise provide data to IoT devices. One example is shown in  FIG. 9A , which shows an IoT hub  110  with program code updates  901  that need to be installed on an IoT device  601  (or a group of such IoT devices). The program code updates may include system updates, patches, configuration data and any other data needed for the IoT device to operate as desired by the user. In one embodiment, the user may specify configuration options for the IoT device  601  via a mobile device or computer which are then stored on the IoT hub  110  and provided to the IoT device using the techniques described herein. Specifically, in one embodiment, the intermediary connection logic/application  721  on the IoT hub  110  communicates with the intermediary connection logic/application  711  on the mobile device  611  to store the program code updates within a temporary storage  615 . When the mobile device  611  enters the range of the IoT device  601 , the intermediary connection logic/application  711  on the mobile device  611  connects with the intermediary/connection logic/application  701  on the IoT device  601  to provide the program code updates to the device. In one embodiment, the IoT device  601  may then enter into an automated update process to install the new program code updates and/or data. 
     A method for updating an IoT device is shown in  FIG. 9B . The method may be implemented within the context of the system architectures described above, but is not limited to any particular system architectures. 
     At  900  new program code or data updates are made available on the IoT hub and/or an external service (e.g., coupled to the mobile device over the Internet). At  901 , the mobile device receives and stores the program code or data updates on behalf of the IoT device. The IoT device and/or mobile device periodically check to determine whether a connection has been established at  902 . If a connection is established, determined at  903 , then at  904  the updates are transferred to the IoT device and installed. 
     Embodiments for Improved Security 
     In one embodiment, the low power microcontroller  200  of each IoT device  101  and the low power logic/microcontroller  301  of the IoT hub  110  include a secure key store for storing encryption keys used by the embodiments described below (see, e.g.,  FIGS. 10-15  and associated text). Alternatively, the keys may be secured in a subscriber identify module (SIM) as discussed below. 
       FIG. 10  illustrates a high level architecture which uses public key infrastructure (PKI) techniques and/or symmetric key exchange/encryption techniques to encrypt communications between the IoT Service  120 , the IoT hub  110  and the IoT devices  101 - 102 . 
     Embodiments which use public/private key pairs will first be described, followed by embodiments which use symmetric key exchange/encryption techniques. In particular, in an embodiment which uses PKI, a unique public/private key pair is associated with each IoT device  101 - 102 , each IoT hub  110  and the IoT service  120 . In one embodiment, when a new IoT hub  110  is set up, its public key is provided to the IoT service  120  and when a new IoT device  101  is set up, it&#39;s public key is provided to both the IoT hub  110  and the IoT service  120 . Various techniques for securely exchanging the public keys between devices are described below. In one embodiment, all public keys are signed by a master key known to all of the receiving devices (i.e., a form of certificate) so that any receiving device can verify the validity of the public keys by validating the signatures. Thus, these certificates would be exchanged rather than merely exchanging the raw public keys. 
     As illustrated, in one embodiment, each IoT device  101 ,  102  includes a secure key storage  1001 ,  1003 , respectively, for security storing each device&#39;s private key. Security logic  1002 ,  1304  then utilizes the securely stored private keys to perform the encryption/decryption operations described herein. Similarly, the IoT hub  110  includes a secure storage  1011  for storing the IoT hub private key and the public keys of the IoT devices  101 - 102  and the IoT service  120 ; as well as security logic  1012  for using the keys to perform encryption/decryption operations. Finally, the IoT service  120  may include a secure storage  1021  for security storing its own private key, the public keys of various IoT devices and IoT hubs, and a security logic  1013  for using the keys to encrypt/decrypt communication with IoT hubs and devices. In one embodiment, when the IoT hub  110  receives a public key certificate from an IoT device it can verify it (e.g., by validating the signature using the master key as described above), and then extract the public key from within it and store that public key in it&#39;s secure key store  1011 . 
     By way of example, in one embodiment, when the IoT service  120  needs to transmit a command or data to an IoT device  101  (e.g., a command to unlock a door, a request to read a sensor, data to be processed/displayed by the IoT device, etc) the security logic  1013  encrypts the data/command using the public key of the IoT device  101  to generate an encrypted IoT device packet. In one embodiment, it then encrypts the IoT device packet using the public key of the IoT hub  110  to generate an IoT hub packet and transmits the IoT hub packet to the IoT hub  110 . In one embodiment, the service  120  signs the encrypted message with it&#39;s private key or the master key mentioned above so that the device  101  can verify it is receiving an unaltered message from a trusted source. The device  101  may then validate the signature using the public key corresponding to the private key and/or the master key. As mentioned above, symmetric key exchange/encryption techniques may be used instead of public/private key encryption. In these embodiments, rather than privately storing one key and providing a corresponding public key to other devices, the devices may each be provided with a copy of the same symmetric key to be used for encryption and to validate signatures. One example of a symmetric key algorithm is the Advanced Encryption Standard (AES), although the underlying principles of the invention are not limited to any type of specific symmetric keys. 
     Using a symmetric key implementation, each device  101  enters into a secure key exchange protocol to exchange a symmetric key with the IoT hub  110 . A secure key provisioning protocol such as the Dynamic Symmetric Key Provisioning Protocol (DSKPP) may be used to exchange the keys over a secure communication channel (see, e.g., Request for Comments (RFC) 6063). However, the underlying principles of the invention are not limited to any particular key provisioning protocol. 
     Once the symmetric keys have been exchanged, they may be used by each device  101  and the IoT hub  110  to encrypt communications. Similarly, the IoT hub  110  and IoT service  120  may perform a secure symmetric key exchange and then use the exchanged symmetric keys to encrypt communications. In one embodiment a new symmetric key is exchanged periodically between the devices  101  and the hub  110  and between the hub  110  and the IoT service  120 . In one embodiment, a new symmetric key is exchanged with each new communication session between the devices  101 , the hub  110 , and the service  120  (e.g., a new key is generated and securely exchanged for each communication session). In one embodiment, if the security module  1012  in the IoT hub is trusted, the service  120  could negotiate a session key with the hub security module  1312  and then the security module  1012  would negotiate a session key with each device  120 . Messages from the service  120  would then be decrypted and verified in the hub security module  1012  before being re-encrypted for transmission to the device  101 . 
     In one embodiment, to prevent a compromise on the hub security module  1012  a one-time (permanent) installation key may be negotiated between the device  101  and service  120  at installation time. When sending a message to a device  101  the service  120  could first encrypt/MAC with this device installation key, then encrypt/MAC that with the hub&#39;s session key. The hub  110  would then verify and extract the encrypted device blob and send that to the device. 
     In one embodiment of the invention, a counter mechanism is implemented to prevent replay attacks. For example, each successive communication from the device  101  to the hub  110  (or vice versa) may be assigned a continually increasing counter value. Both the hub  110  and device  101  will track this value and verify that the value is correct in each successive communication between the devices. The same techniques may be implemented between the hub  110  and the service  120 . Using a counter in this manner would make it more difficult to spoof the communication between each of the devices (because the counter value would be incorrect). However, even without this a shared installation key between the service and device would prevent network (hub) wide attacks to all devices. 
     In one embodiment, when using public/private key encryption, the IoT hub  110  uses its private key to decrypt the IoT hub packet and generate the encrypted IoT device packet, which it transmits to the associated IoT device  101 . The IoT device  101  then uses its private key to decrypt the IoT device packet to generate the command/data originated from the IoT service  120 . It may then process the data and/or execute the command. Using symmetric encryption, each device would encrypt and decrypt with the shared symmetric key. If either case, each transmitting device may also sign the message with it&#39;s private key so that the receiving device can verify it&#39;s authenticity. 
     A different set of keys may be used to encrypt communication from the IoT device  101  to the IoT hub  110  and to the IoT service  120 . For example, using a public/private key arrangement, in one embodiment, the security logic  1002  on the IoT device  101  uses the public key of the IoT hub  110  to encrypt data packets sent to the IoT hub  110 . The security logic  1012  on the IoT hub  110  may then decrypt the data packets using the IoT hub&#39;s private key. Similarly, the security logic  1002  on the IoT device  101  and/or the security logic  1012  on the IoT hub  110  may encrypt data packets sent to the IoT service  120  using the public key of the IoT service  120  (which may then be decrypted by the security logic  1013  on the IoT service  120  using the service&#39;s private key). Using symmetric keys, the device  101  and hub  110  may share a symmetric key while the hub and service  120  may share a different symmetric key. 
     While certain specific details are set forth above in the description above, it should be noted that the underlying principles of the invention may be implemented using various different encryption techniques. For example, while some embodiments discussed above use asymmetric public/private key pairs, an alternate embodiment may use symmetric keys securely exchanged between the various IoT devices  101 - 102 , IoT hubs  110 , and the IoT service  120 . Moreover, in some embodiments, the data/command itself is not encrypted, but a key is used to generate a signature over the data/command (or other data structure). The recipient may then use its key to validate the signature. 
     As illustrated in  FIG. 11 , in one embodiment, the secure key storage on each IoT device  101  is implemented using a programmable subscriber identity module (SIM)  1101 . In this embodiment, the IoT device  101  may initially be provided to the end user with an un-programmed SIM card  1101  seated within a SIM interface  1100  on the IoT device  101 . In order to program the SIM with a set of one or more encryption keys, the user takes the programmable SIM card  1101  out of the SIM interface  500  and inserts it into a SIM programming interface  1102  on the IoT hub  110 . Programming logic  1125  on the IoT hub then securely programs the SIM card  1101  to register/pair the IoT device  101  with the IoT hub  110  and IoT service  120 . In one embodiment, a public/private key pair may be randomly generated by the programming logic  1125  and the public key of the pair may then be stored in the IoT hub&#39;s secure storage device  411  while the private key may be stored within the programmable SIM  1101 . In addition, the programming logic  525  may store the public keys of the IoT hub  110 , the IoT service  120 , and/or any other IoT devices  101  on the SIM card  1401  (to be used by the security logic  1302  on the IoT device  101  to encrypt outgoing data). Once the SIM  1101  is programmed, the new IoT device  101  may be provisioned with the IoT Service  120  using the SIM as a secure identifier (e.g., using existing techniques for registering a device using a SIM). Following provisioning, both the IoT hub  110  and the IoT service  120  will securely store a copy of the IoT device&#39;s public key to be used when encrypting communication with the IoT device  101 . 
     The techniques described above with respect to  FIG. 11  provide enormous flexibility when providing new IoT devices to end users. Rather than requiring a user to directly register each SIM with a particular service provider upon sale/purchase (as is currently done), the SIM may be programmed directly by the end user via the IoT hub  110  and the results of the programming may be securely communicated to the IoT service  120 . Consequently, new IoT devices  101  may be sold to end users from online or local retailers and later securely provisioned with the IoT service  120 . 
     While the registration and encryption techniques are described above within the specific context of a SIM (Subscriber Identity Module), the underlying principles of the invention are not limited to a “SIM” device. Rather, the underlying principles of the invention may be implemented using any type of device having secure storage for storing a set of encryption keys. Moreover, while the embodiments above include a removable SIM device, in one embodiment, the SIM device is not removable but the IoT device itself may be inserted within the programming interface  1102  of the IoT hub  110 . 
     In one embodiment, rather than requiring the user to program the SIM (or other device), the SIM is pre-programmed into the IoT device  101 , prior to distribution to the end user. In this embodiment, when the user sets up the IoT device  101 , various techniques described herein may be used to securely exchange encryption keys between the IoT hub  110 /IoT service  120  and the new IoT device  101 . 
     For example, as illustrated in  FIG. 12A  each IoT device  101  or SIM  401  may be packaged with a barcode or QR code  1501  uniquely identifying the IoT device  101  and/or SIM  1001 . In one embodiment, the barcode or QR code  1201  comprises an encoded representation of the public key for the IoT device  101  or SIM  1001 . Alternatively, the barcode or QR code  1201  may be used by the IoT hub  110  and/or IoT service  120  to identify or generate the public key (e.g., used as a pointer to the public key which is already stored in secure storage). The barcode or QR code  601  may be printed on a separate card (as shown in  FIG. 12A ) or may be printed directly on the IoT device itself. Regardless of where the barcode is printed, in one embodiment, the IoT hub  110  is equipped with a barcode reader  206  for reading the barcode and providing the resulting data to the security logic  1012  on the IoT hub  110  and/or the security logic  1013  on the IoT service  120 . The security logic  1012  on the IoT hub  110  may then store the public key for the IoT device within its secure key storage  1011  and the security logic  1013  on the IoT service  120  may store the public key within its secure storage  1021  (to be used for subsequent encrypted communication). 
     In one embodiment, the data contained in the barcode or QR code  1201  may also be captured via a user device  135  (e.g., such as an iPhone or Android device) with an installed IoT app or browser-based applet designed by the IoT service provider. Once captured, the barcode data may be securely communicated to the IoT service  120  over a secure connection (e.g., such as a secure sockets layer (SSL) connection). The barcode data may also be provided from the client device  135  to the IoT hub  110  over a secure local connection (e.g., over a local WiFi or Bluetooth LE connection). 
     The security logic  1002  on the IoT device  101  and the security logic  1012  on the IoT hub  110  may be implemented using hardware, software, firmware or any combination thereof. For example, in one embodiment, the security logic  1002 ,  1012  is implemented within the chips used for establishing the local communication channel  130  between the IoT device  101  and the IoT hub  110  (e.g., the Bluetooth LE chip if the local channel  130  is Bluetooth LE). Regardless of the specific location of the security logic  1002 ,  1012 , in one embodiment, the security logic  1002 ,  1012  is designed to establish a secure execution environment for executing certain types of program code. This may be implemented, for example, by using TrustZone technology (available on some ARM processors) and/or Trusted Execution Technology (designed by Intel). Of course, the underlying principles of the invention are not limited to any particular type of secure execution technology. 
     In one embodiment, the barcode or QR code  1501  may be used to pair each IoT device  101  with the IoT hub  110 . For example, rather than using the standard wireless pairing process currently used to pair Bluetooth LE devices, a pairing code embedded within the barcode or QR code  1501  may be provided to the IoT hub  110  to pair the IoT hub with the corresponding IoT device. 
       FIG. 12B  illustrates one embodiment in which the barcode reader  206  on the IoT hub  110  captures the barcode/QR code  1201  associated with the IoT device  101 . As mentioned, the barcode/QR code  1201  may be printed directly on the IoT device  101  or may be printed on a separate card provided with the IoT device  101 . In either case, the barcode reader  206  reads the pairing code from the barcode/QR code  1201  and provides the pairing code to the local communication module  1280 . In one embodiment, the local communication module  1280  is a Bluetooth LE chip and associated software, although the underlying principles of the invention are not limited to any particular protocol standard. Once the pairing code is received, it is stored in a secure storage containing pairing data  1285  and the IoT device  101  and IoT hub  110  are automatically paired. Each time the IoT hub is paired with a new IoT device in this manner, the pairing data for that pairing is stored within the secure storage  685 . In one embodiment, once the local communication module  1280  of the IoT hub  110  receives the pairing code, it may use the code as a key to encrypt communications over the local wireless channel with the IoT device  101 . 
     Similarly, on the IoT device  101  side, the local communication module  1590  stores pairing data within a local secure storage device  1595  indicating the pairing with the IoT hub. The pairing data  1295  may include the pre-programmed pairing code identified in the barcode/QR code  1201 . The pairing data  1295  may also include pairing data received from the local communication module  1280  on the IoT hub  110  required for establishing a secure local communication channel (e.g., an additional key to encrypt communication with the IoT hub  110 ). 
     Thus, the barcode/QR code  1201  may be used to perform local pairing in a far more secure manner than current wireless pairing protocols because the pairing code is not transmitted over the air. In addition, in one embodiment, the same barcode/QR code  1201  used for pairing may be used to identify encryption keys to build a secure connection from the IoT device  101  to the IoT hub  110  and from the IoT hub  110  to the IoT service  120 . 
     A method for programming a SIM card in accordance with one embodiment of the invention is illustrated in  FIG. 13 . The method may be implemented within the system architecture described above, but is not limited to any particular system architecture. 
     At  1301 , a user receives a new IoT device with a blank SIM card and, at  1602 , the user inserts the blank SIM card into an IoT hub. At  1303 , the user programs the blank SIM card with a set of one or more encryption keys. For example, as mentioned above, in one embodiment, the IoT hub may randomly generate a public/private key pair and store the private key on the SIM card and the public key in its local secure storage. In addition, at  1304 , at least the public key is transmitted to the IoT service so that it may be used to identify the IoT device and establish encrypted communication with the IoT device. As mentioned above, in one embodiment, a programmable device other than a “SIM” card may be used to perform the same functions as the SIM card in the method shown in  FIG. 13 . 
     A method for integrating a new IoT device into a network is illustrated in  FIG. 14 . The method may be implemented within the system architecture described above, but is not limited to any particular system architecture. 
     At  1401 , a user receives a new IoT device to which an encryption key has been pre-assigned. At  1402 , the key is securely provided to the IoT hub. As mentioned above, in one embodiment, this involves reading a barcode associated with the IoT device to identify the public key of a public/private key pair assigned to the device. The barcode may be read directly by the IoT hub or captured via a mobile device via an app or browser. In an alternate embodiment, a secure communication channel such as a Bluetooth LE channel, a near field communication (NFC) channel or a secure WiFi channel may be established between the IoT device and the IoT hub to exchange the key. Regardless of how the key is transmitted, once received, it is stored in the secure keystore of the IoT hub device. As mentioned above, various secure execution technologies may be used on the IoT hub to store and protect the key such as Secure Enclaves, Trusted Execution Technology (TXT), and/or Trustzone. In addition, at  803 , the key is securely transmitted to the IoT service which stores the key in its own secure keystore. It may then use the key to encrypt communication with the IoT device. One again, the exchange may be implemented using a certificate/signed key. Within the hub  110  it is particularly important to prevent modification/addition/removal of the stored keys. 
     A method for securely communicating commands/data to an IoT device using public/private keys is illustrated in  FIG. 15 . The method may be implemented within the system architecture described above, but is not limited to any particular system architecture. 
     At  1501 , the IoT service encrypts the data/commands using the IoT device public key to create an IoT device packet. It then encrypts the IoT device packet using IoT hub&#39;s public key to create the IoT hub packet (e.g., creating an IoT hub wrapper around the IoT device packet). At  1502 , the IoT service transmits the IoT hub packet to the IoT hub. At  1503 , the IoT hub decrypts the IoT hub packet using the IoT hub&#39;s private key to generate the IoT device packet. At  1504  it then transmits the IoT device packet to the IoT device which, at  1505 , decrypts the IoT device packet using the IoT device private key to generate the data/commands. At  1506 , the IoT device processes the data/commands. 
     In an embodiment which uses symmetric keys, a symmetric key exchange may be negotiated between each of the devices (e.g., each device and the hub and between the hub and the service). Once the key exchange is complete, each transmitting device encrypts and/or signs each transmission using the symmetric key before transmitting data to the receiving device. 
     Apparatus and Method for Establishing Secure Communication Channels in an Internet of Things (IoT) System 
     In one embodiment of the invention, encryption and decryption of data is performed between the IoT service  120  and each IoT device  101 , regardless of the intermediate devices used to support the communication channel (e.g., such as the user&#39;s mobile device  611  and/or the IoT hub  110 ). One embodiment which communicates via an IoT hub  110  is illustrated in  FIG. 16A  and another embodiment which does not require an IoT hub is illustrated in  FIG. 16B . 
     Turning first to  FIG. 16A , the IoT service  120  includes an encryption engine  1660  which manages a set of “service session keys”  1650  and each IoT device  101  includes an encryption engine  1661  which manages a set of “device session keys”  1651  for encrypting/decrypting communication between the IoT device  101  and IoT service  120 . The encryption engines may rely on different hardware modules when performing the security/encryption techniques described herein including a hardware security module  1630 - 1631  for (among other things) generating a session public/private key pair and preventing access to the private session key of the pair and a key stream generation module  1640 - 1641  for generating a key stream using a derived secret. In one embodiment, the service session keys  1650  and the device session keys  1651  comprise related public/private key pairs. For example, in one embodiment, the device session keys  1651  on the IoT device  101  include a public key of the IoT service  120  and a private key of the IoT device  101 . As discussed in detail below, in one embodiment, to establish a secure communication session, the public/private session key pairs,  1650  and  1651 , are used by each encryption engine,  1660  and  1661 , respectively, to generate the same secret which is then used by the SKGMs  1640 - 1641  to generate a key stream to encrypt and decrypt communication between the IoT service  120  and the IoT device  101 . Additional details associated with generation and use of the secret in accordance with one embodiment of the invention are provided below. 
     In  FIG. 16A , once the secret has been generated using the keys  1650 - 1651 , the client will always send messages to the IoT device  101  through the IoT service  120 , as indicated by Clear transaction  1611 . “Clear” as used herein is meant to indicate that the underlying message is not encrypted using the encryption techniques described herein. However, as illustrated, in one embodiment, a secure sockets layer (SSL) channel or other secure channel (e.g., an Internet Protocol Security (IPSEC) channel) is established between the client device  611  and IoT service  120  to protect the communication. The encryption engine  1660  on the IoT service  120  then encrypts the message using the generated secret and transmits the encrypted message to the IoT hub  110  at  1602 . Rather than using the secret to encrypt the message directly, in one embodiment, the secret and a counter value are used to generate a key stream, which is used to encrypt each message packet. Details of this embodiment are described below with respect to  FIG. 17 . 
     As illustrated, an SSL connection or other secure channel may be established between the IoT service  120  and the IoT hub  110 . The IoT hub  110  (which does not have the ability to decrypt the message in one embodiment) transmits the encrypted message to the IoT device at  1603  (e.g., over a Bluetooth Low Energy (BTLE) communication channel). The encryption engine  1661  on the IoT device  101  may then decrypt the message using the secret and process the message contents. In an embodiment which uses the secret to generate a key stream, the encryption engine  1661  may generate the key stream using the secret and a counter value and then use the key stream for decryption of the message packet. 
     The message itself may comprise any form of communication between the IoT service  120  and IoT device  101 . For example, the message may comprise a command packet instructing the IoT device  101  to perform a particular function such as taking a measurement and reporting the result back to the client device  611  or may include configuration data to configure the operation of the IoT device  101 . 
     If a response is required, the encryption engine  1661  on the IoT device  101  uses the secret or a derived key stream to encrypt the response and transmits the encrypted response to the IoT hub  110  at  1604 , which forwards the response to the IoT service  120  at  1605 . The encryption engine  1660  on the IoT service  120  then decrypts the response using the secret or a derived key stream and transmits the decrypted response to the client device  611  at  1606  (e.g., over the SSL or other secure communication channel). 
       FIG. 16B  illustrates an embodiment which does not require an IoT hub. Rather, in this embodiment, communication between the IoT device  101  and IoT service  120  occurs through the client device  611  (e.g., as in the embodiments described above with respect to  FIGS. 6-9B ). In this embodiment, to transmit a message to the IoT device  101  the client device  611  transmits an unencrypted version of the message to the IoT service  120  at  1611 . The encryption engine  1660  encrypts the message using the secret or the derived key stream and transmits the encrypted message back to the client device  611  at  1612 . The client device  611  then forwards the encrypted message to the IoT device  101  at  1613 , and the encryption engine  1661  decrypts the message using the secret or the derived key stream. The IoT device  101  may then process the message as described herein. If a response is required, the encryption engine  1661  encrypts the response using the secret and transmits the encrypted response to the client device  611  at  1614 , which forwards the encrypted response to the IoT service  120  at  1615 . The encryption engine  1660  then decrypts the response and transmits the decrypted response to the client device  611  at  1616 . 
       FIG. 17  illustrates a key exchange and key stream generation which may initially be performed between the IoT service  120  and the IoT device  101 . In one embodiment, this key exchange may be performed each time the IoT service  120  and IoT device  101  establish a new communication session. Alternatively, the key exchange may be performed and the exchanged session keys may be used for a specified period of time (e.g., a day, a week, etc). While no intermediate devices are shown in  FIG. 17  for simplicity, communication may occur through the IoT hub  110  and/or the client device  611 . 
     In one embodiment, the encryption engine  1660  of the IoT service  120  sends a command to the HSM  1630  (e.g., which may be such as a CloudHSM offered by Amazon®) to generate a session public/private key pair. The HSM  1630  may subsequently prevent access to the private session key of the pair. Similarly, the encryption engine on the IoT device  101  may transmit a command to the HSM  1631  (e.g., such as an Atecc508 HSM from Atmel Corporation®) which generates a session public/private key pair and prevents access to the session private key of the pair. Of course, the underlying principles of the invention are not limited to any specific type of encryption engine or manufacturer. 
     In one embodiment, the IoT service  120  transmits its session public key generated using the HSM  1630  to the IoT device  101  at  1701 . The IoT device uses its HSM  1631  to generate its own session public/private key pair and, at  1702 , transmits its public key of the pair to the IoT service  120 . In one embodiment, the encryption engines  1660 - 1661  use an Elliptic curve Diffie-Hellman (ECDH) protocol, which is an anonymous key agreement that allows two parties with an elliptic curve public-private key pair, to establish a shared secret. In one embodiment, using these techniques, at  1703 , the encryption engine  1660  of the IoT service  120  generates the secret using the IoT device session public key and its own session private key. Similarly, at  1704 , the encryption engine  1661  of the IoT device  101  independently generates the same secret using the IoT service  120  session public key and its own session private key. More specifically, in one embodiment, the encryption engine  1660  on the IoT service  120  generates the secret according to the formula secret=IoT device session pub key*IoT service session private key, where “*” means that the IoT device session public key is point-multiplied by the IoT service session private key. The encryption engine  1661  on the IoT device  101  generates the secret according to the formula secret=IoT service session pub key*IoT device session private key, where the IoT service session public key is point multiplied by the IoT device session private key. In the end, the IoT service  120  and IoT device  101  have both generated the same secret to be used to encrypt communication as described below. In one embodiment, the encryption engines  1660 - 1661  rely on a hardware module such as the KSGMs  1640 - 1641  respectively to perform the above operations for generating the secret. 
     Once the secret has been determined, it may be used by the encryption engines  1660  and  1661  to encrypt and decrypt data directly. Alternatively, in one embodiment, the encryption engines  1660 - 1661  send commands to the KSGMs  1640 - 1641  to generate a new key stream using the secret to encrypt/decrypt each data packet (i.e., a new key stream data structure is generated for each packet). In particular, one embodiment of the key stream generation module  1640 - 1641  implements a Galois/Counter Mode (GCM) in which a counter value is incremented for each data packet and is used in combination with the secret to generate the key stream. Thus, to transmit a data packet to the IoT service  120 , the encryption engine  1661  of the IoT device  101  uses the secret and the current counter value to cause the KSGMs  1640 - 1641  to generate a new key stream and increment the counter value for generating the next key stream. The newly-generated key stream is then used to encrypt the data packet prior to transmission to the IoT service  120 . In one embodiment, the key stream is XORed with the data to generate the encrypted data packet. In one embodiment, the IoT device  101  transmits the counter value with the encrypted data packet to the IoT service  120 . The encryption engine  1660  on the IoT service then communicates with the KSGM  1640  which uses the received counter value and the secret to generate the key stream (which should be the same key stream because the same secret and counter value are used) and uses the generated key stream to decrypt the data packet. 
     In one embodiment, data packets transmitted from the IoT service  120  to the IoT device  101  are encrypted in the same manner. Specifically, a counter is incremented for each data packet and used along with the secret to generate a new key stream. The key stream is then used to encrypt the data (e.g., performing an XOR of the data and the key stream) and the encrypted data packet is transmitted with the counter value to the IoT device  101 . The encryption engine  1661  on the IoT device  101  then communicates with the KSGM  1641  which uses the counter value and the secret to generate the same key stream which is used to decrypt the data packet. Thus, in this embodiment, the encryption engines  1660 - 1661  use their own counter values to generate a key stream to encrypt data and use the counter values received with the encrypted data packets to generate a key stream to decrypt the data. 
     In one embodiment, each encryption engine  1660 - 1661  keeps track of the last counter value it received from the other and includes sequencing logic to detect whether a counter value is received out of sequence or if the same counter value is received more than once. If a counter value is received out of sequence, or if the same counter value is received more than once, this may indicate that a replay attack is being attempted. In response, the encryption engines  1660 - 1661  may disconnect from the communication channel and/or may generate a security alert. 
       FIG. 18  illustrates an exemplary encrypted data packet employed in one embodiment of the invention comprising a 4-byte counter value  1800 , a variable-sized encrypted data field  1801 , and a 6-byte tag  1802 . In one embodiment, the tag  1802  comprises a checksum value to validate the decrypted data (once it has been decrypted). 
     As mentioned, in one embodiment, the session public/private key pairs  1650 - 1651  exchanged between the IoT service  120  and IoT device  101  may be generated periodically and/or in response to the initiation of each new communication session. 
     One embodiment of the invention implements additional techniques for authenticating sessions between the IoT service  120  and IoT device  101 . In particular, in one embodiment, hierarchy of public/private key pairs is used including a master key pair, a set of factory key pairs, and a set of IoT service key pairs, and a set of IoT device key pairs. In one embodiment, the master key pair comprises a root of trust for all of the other key pairs and is maintained in a single, highly secure location (e.g., under the control of the organization implementing the IoT systems described herein). The master private key may be used to generate signatures over (and thereby authenticate) various other key pairs such as the factory key pairs. The signatures may then be verified using the master public key. In one embodiment, each factory which manufactures IoT devices is assigned its own factory key pair which may then be used to authenticate IoT service keys and IoT device keys. For example, in one embodiment, a factory private key is used to generate a signature over IoT service public keys and IoT device public keys. These signature may then be verified using the corresponding factory public key. Note that these IoT service/device public keys are not the same as the “session” public/private keys described above with respect to  FIGS. 16A-B . The session public/private keys described above are temporary (i.e., generated for a service/device session) while the IoT service/device key pairs are permanent (i.e., generated at the factory). 
     With the foregoing relationships between master keys, factory keys, service/device keys in mind, one embodiment of the invention performs the following operations to provide additional layers of authentication and security between the IoT service  120  and IoT device  101 : 
     A. In one embodiment, the IoT service  120  initially generates a message containing the following:
         1. The IoT service&#39;s unique ID:
           The IoT service&#39;s serial number;   a Timestamp;   The ID of the factory key used to sign this unique ID;   a Class of the unique ID (i.e., a service);   IoT service&#39;s public key   The signature over the unique ID.   
           2. The Factory Certificate including:
           A timestamp   The ID of the master key used to sign the certificate   The factory public key   The signature of the Factory Certificate   
           3. IoT service session public key (as described above with respect to  FIGS. 16A-B )   4. IoT service session public key signature (e.g., signed with the IoT service&#39;s private key)       

     B. In one embodiment, the message is sent to the IoT device on the negotiation channel (described below). The IoT device parses the message and:
         1. Verifies the signature of the factory certificate (only if present in the message payload)   2. Verifies the signature of the unique ID using the key identified by the unique ID   3. Verifies the IoT service session public key signature using the IoT service&#39;s public key from the unique ID   4. Saves the IoT service&#39;s public key as well as the IoT service&#39;s session public key   5. Generates the IoT device session key pair       

     C. The IoT device then generates a message containing the following:
         1. IoT device&#39;s unique ID
           IoT device serial number   Timestamp   ID of factory key used to sign this unique ID   Class of unique ID (i.e., IoT device)   IoT device&#39;s public key   Signature of unique ID   
           2. IoT device&#39;s session public key   3. Signature of (IoT device session public key+IoT service session public key) signed with IoT device&#39;s key       

     D. This message is sent back to the IoT service. The IoT service parses the message and:
         1. Verifies the signature of the unique ID using the factory public key   2. Verifies the signature of the session public keys using the IoT device&#39;s public key   3. Saves the IoT device&#39;s session public key       

     E. The IoT service then generates a message containing a signature of (IoT device session public key+IoT service session public key) signed with the IoT service&#39;s key. 
     F. The IoT device parses the message and:
         1. Verifies the signature of the session public keys using the IoT service&#39;s public key   2. Generates the key stream from the IoT device session private key and the IoT service&#39;s session public key   3. The IoT device then sends a “messaging available” message.       

     G. The IoT service then does the following:
         1. Generates the key stream from the IoT service session private key and the IoT device&#39;s session public key   2. Creates a new message on the messaging channel which contains the following:
           Generates and stores a random 2 byte value   Set attribute message with the boomerang attribute Id (discussed below) and the random value   
               

     H. The IoT device receives the message and:
         1. Attempts to decrypt the message   2. Emits an Update with the same value on the indicated attribute Id       

     I. The IoT service recognizes the message payload contains a boomerang attribute update and:
         1. Sets its paired state to true   2. Sends a pairing complete message on the negotiator channel       

     J. IoT device receives the message and sets his paired state to true 
     While the above techniques are described with respect to an “IoT service” and an “IoT device,” the underlying principles of the invention may be implemented to establish a secure communication channel between any two devices including user client devices, servers, and Internet services. 
     The above techniques are highly secure because the private keys are never shared over the air (in contrast to current Bluetooth pairing techniques in which a secret is transmitted from one party to the other). An attacker listening to the entire conversation will only have the public keys, which are insufficient to generate the shared secret. These techniques also prevent a man-in-the-middle attack by exchanging signed public keys. In addition, because GCM and separate counters are used on each device, any kind of “replay attack” (where a man in the middle captures the data and sends it again) is prevented. Some embodiments also prevent replay attacks by using asymmetrical counters. 
     Techniques for Exchanging Data and Commands without Formally Pairing Devices 
     GATT is an acronym for the Generic Attribute Profile, and it defines the way that two Bluetooth Low Energy (BTLE) devices transfer data back and forth. It makes use of a generic data protocol called the Attribute Protocol (ATT), which is used to store Services, Characteristics and related data in a simple lookup table using 16-bit Characteristic IDs for each entry in the table. Note that while the “characteristics” are sometimes referred to as “attributes.” 
     On Bluetooth devices, the most commonly used characteristic is the devices “name” (having characteristic ID 10752 (0x2A00)). For example, a Bluetooth device may identify other Bluetooth devices within its vicinity by reading the “Name” characteristic published by those other Bluetooth devices using GATT. Thus, Bluetooth device have the inherent ability to exchange data without formally pairing/bonding the devices (note that “paring” and “bonding” are sometimes used interchangeably; the remainder of this discussion will use the term “pairing”). 
     One embodiment of the invention takes advantage of this capability to communicate with BTLE-enabled IoT devices without formally pairing with these devices. Pairing with each individual IoT device would extremely inefficient because of the amount of time required to pair with each device and because only one paired connection may be established at a time. 
       FIG. 19  illustrates one particular embodiment in which a Bluetooth (BT) device  1910  establishes a network socket abstraction with a BT communication module  1901  of an IoT device  101  without formally establishing a paired BT connection. The BT device  1910  may be included in an IoT hub  110  and/or a client device  611  such as shown in  FIG. 16A . As illustrated, the BT communication module  1901  maintains a data structure containing a list of characteristic IDs, names associated with those characteristic IDs and values for those characteristic IDs. The value for each characteristic may be stored within a 20-byte buffer identified by the characteristic ID in accordance with the current BT standard. However, the underlying principles of the invention are not limited to any particular buffer size. 
     In the example in  FIG. 19 , the “Name” characteristic is a BT-defined characteristic which is assigned a specific value of “IoT Device  14 .” One embodiment of the invention specifies a first set of additional characteristics to be used for negotiating a secure communication channel with the BT device  1910  and a second set of additional characteristics to be used for encrypted communication with the BT device  1910 . In particular, a “negotiation write” characteristic, identified by characteristic ID &lt;65532&gt; in the illustrated example, may be used to transmit outgoing negotiation messages and the “negotiation read” characteristic, identified by characteristic ID &lt;65533&gt; may be used to receive incoming negotiation messages. The “negotiation messages” may include messages used by the BT device  1910  and the BT communication module  1901  to establish a secure communication channel as described herein. By way of example, in  FIG. 17 , the IoT device  101  may receive the IoT service session public key  1701  via the “negotiation read” characteristic &lt;65533&gt;. The key  1701  may be transmitted from the IoT service  120  to a BTLE-enabled IoT hub  110  or client device  611  which may then use GATT to write the key  1701  to the negotiation read value buffer identified by characteristic ID &lt;65533&gt;. IoT device application logic  1902  may then read the key  1701  from the value buffer identified by characteristic ID &lt;65533&gt; and process it as described above (e.g., using it to generate a secret and using the secret to generate a key stream, etc). 
     If the key  1701  is greater than 20 bytes (the maximum buffer size in some current implementations), then it may be written in 20-byte portions. For example, the first 20 bytes may be written by the BT communication module  1903  to characteristic ID &lt;65533&gt; and read by the IoT device application logic  1902 , which may then write an acknowledgement message to the negotiation write value buffer identified by characteristic ID &lt;65532&gt;. Using GATT, the BT communication module  1903  may read this acknowledgement from characteristic ID &lt;65532&gt; and responsively write the next 20 bytes of the key  1701  to the negotiation read value buffer identified by characteristic ID &lt;65533&gt;. In this manner, a network socket abstraction defined by characteristic IDs &lt;65532&gt; and &lt;65533&gt; is established for exchanging negotiation messages used to establish a secure communication channel. 
     In one embodiment, once the secure communication channel is established, a second network socket abstraction is established using characteristic ID &lt;65534&gt; (for transmitting encrypted data packets from IoT device  101 ) and characteristic ID &lt;65533&gt; (for receiving encrypted data packets by IoT device). That is, when BT communication module  1903  has an encrypted data packet to transmit (e.g., such as encrypted message  1603  in  FIG. 16A ), it starts writing the encrypted data packet, 20 bytes at a time, using the message read value buffer identified by characteristic ID &lt;65533&gt;. The IoT device application logic  1902  will then read the encrypted data packet, 20 bytes at a time, from the read value buffer, sending acknowledgement messages to the BT communication module  1903  as needed via the write value buffer identified by characteristic ID &lt;65532&gt;. 
     In one embodiment, the commands of GET, SET, and UPDATE described below are used to exchange data and commands between the two BT communication modules  1901  and  1903 . For example, the BT communication module  1903  may send a packet identifying characteristic ID &lt;65533&gt; and containing the SET command to write into the value field/buffer identified by characteristic ID &lt;65533&gt; which may then be read by the IoT device application logic  1902 . To retrieve data from the IoT device  101 , the BT communication module  1903  may transmit a GET command directed to the value field/buffer identified by characteristic ID &lt;65534&gt;. In response to the GET command, the BT communication module  1901  may transmit an UPDATE packet to the BT communication module  1903  containing the data from the value field/buffer identified by characteristic ID &lt;65534&gt;. In addition, UPDATE packets may be transmitted automatically, in response to changes in a particular attribute on the IoT device  101 . For example, if the IoT device is associated with a lighting system and the user turns on the lights, then an UPDATE packet may be sent to reflect the change to the on/off attribute associated with the lighting application. 
       FIG. 20  illustrates exemplary packet formats used for GET, SET, and UPDATE in accordance with one embodiment of the invention. In one embodiment, these packets are transmitted over the message write &lt;65534&gt; and message read &lt;65533&gt; channels following negotiation. In the GET packet  2001 , a first 1-byte field includes a value (0X10) which identifies the packet as a GET packet. A second 1-byte field includes a request ID, which uniquely identifies the current GET command (i.e., identifies the current transaction with which the GET command is associated). For example, each instance of a GET command transmitted from a service or device may be assigned a different request ID. This may be done, for example, by incrementing a counter and using the counter value as the request ID. However, the underlying principles of the invention are not limited to any particular manner for setting the request ID. 
     A 2-byte attribute ID identifies the application-specific attribute to which the packet is directed. For example, if the GET command is being sent to IoT device  101  illustrated in  FIG. 19 , the attribute ID may be used to identify the particular application-specific value being requested. Returning to the above example, the GET command may be directed to an application-specific attribute ID such as power status of a lighting system, which comprises a value identifying whether the lights are powered on or off (e.g., 1=on, 0=off). If the IoT device  101  is a security apparatus associated with a door, then the value field may identify the current status of the door (e.g., 1=opened, 0=closed). In response to the GET command, a response may be transmitting containing the current value identified by the attribute ID. 
     The SET packet  2002  and UPDATE packet  2003  illustrated in  FIG. 20  also include a first 1-byte field identifying the type of packet (i.e., SET and UPDATE), a second 1-byte field containing a request ID, and a 2-byte attribute ID field identifying an application-defined attribute. In addition, the SET packet includes a 2-byte length value identifying the length of data contained in an n-byte value data field. The value data field may include a command to be executed on the IoT device and/or configuration data to configure the operation of the IoT device in some manner (e.g., to set a desired parameter, to power down the IoT device, etc). For example, if the IoT device  101  controls the speed of a fan, the value field may reflect the current fan speed. 
     The UPDATE packet  2003  may be transmitted to provide an update of the results of the SET command. The UPDATE packet  2003  includes a 2-byte length value field to identify the length of the n-byte value data field which may include data related to the results of the SET command. In addition, a 1-byte update state field may identify the current state of the variable being updated. For example, if the SET command attempted to turn off a light controlled by the IoT device, the update state field may indicate whether the light was successfully turned off. 
       FIG. 21  illustrates an exemplary sequence of transactions between the IoT service  120  and an IoT device  101  involving the SET and UPDATE commands. Intermediary devices such as the IoT hub and the user&#39;s mobile device are not shown to avoid obscuring the underlying principles of the invention. At  2101 , the SET command  2101  is transmitted form the IoT service to the IoT device  101  and received by the BT communication module  1901  which responsively updates the GATT value buffer identified by the characteristic ID at  2102 . The SET command is read from the value buffer by the low power microcontroller (MCU)  200  at  2103  (or by program code being executed on the low power MCU such as IoT device application logic  1902  shown in  FIG. 19 ). At  2104 , the MCU  200  or program code performs an operation in response to the SET command. For example, the SET command may include an attribute ID specifying a new configuration parameter such as a new temperature or may include a state value such as on/off (to cause the IoT device to enter into an “on” or a low power state). Thus, at  2104 , the new value is set in the IoT device and an UPDATE command is returned at  2105  and the actual value is updated in a GATT value field at  2106 . In some cases, the actual value will be equal to the desired value. In other cases, the updated value may be different (i.e., because it may take time for the IoT device  101  to update certain types of values). Finally, at  2107 , the UPDATE command is transmitted back to the IoT service  120  containing the actual value from the GATT value field. 
       FIG. 22  illustrates a method for implementing a secure communication channel between an IoT service and an IoT device in accordance with one embodiment of the invention. The method may be implemented within the context of the network architectures described above but is not limited to any specific architecture. 
     At  2201 , the IoT service creates an encrypted channel to communicate with the IoT hub using elliptic curve digital signature algorithm (ECDSA) certificates. At  2202 , the IoT service encrypts data/commands in IoT device packets using the a session secret to create an encrypted device packet. As mentioned above, the session secret may be independently generated by the IoT device and the IoT service. At  2203 , the IoT service transmits the encrypted device packet to the IoT hub over the encrypted channel. At  2204 , without decrypting, the IoT hub passes the encrypted device packet to the IoT device. At  2205 , the IoT device uses the session secret to decrypt the encrypted device packet. As mentioned, in one embodiment this may be accomplished by using the secret and a counter value (provided with the encrypted device packet) to generate a key stream and then using the key stream to decrypt the packet. At  2206 , the IoT device then extracts and processes the data and/or commands contained within the device packet. 
     Thus, using the above techniques, bi-directional, secure network socket abstractions may be established between two BT-enabled devices without formally pairing the BT devices using standard pairing techniques. While these techniques are described above with respect to an IoT device  101  communicating with an IoT service  120 , the underlying principles of the invention may be implemented to negotiate and establish a secure communication channel between any two BT-enabled devices. 
       FIGS. 23A-C  illustrate a detailed method for pairing devices in accordance with one embodiment of the invention. The method may be implemented within the context of the system architectures described above, but is not limited to any specific system architectures. 
     At  2301 , the IoT Service creates a packet containing serial number and public key of the IoT Service. At  2302 , the IoT Service signs the packet using the factory private key. At  2303 , the IoT Service sends the packet over an encrypted channel to the IoT hub and at  2304  the IoT hub forwards the packet to IoT device over an unencrypted channel. At  2305 , the IoT device verifies the signature of packet and, at  2306 , the IoT device generates a packet containing the serial number and public key of the IoT Device. At  2307 , the IoT device signs the packet using the factory private key and at  2308 , the IoT device sends the packet over the unencrypted channel to the IoT hub. 
     At  2309 , the IoT hub forwards the packet to the IoT service over an encrypted channel and at  2310 , the IoT Service verifies the signature of the packet. At  2311 , the IoT Service generates a session key pair, and at  2312  the IoT Service generates a packet containing the session public key. The IoT Service then signs the packet with IoT Service private key at  2313  and, at  2314 , the IoT Service sends the packet to the IoT hub over the encrypted channel. 
     Turning to  FIG. 23B , the IoT hub forwards the packet to the IoT device over the unencrypted channel at  2315  and, at  2316 , the IoT device verifies the signature of packet. At  2317  the IoT device generates session key pair (e.g., using the techniques described above), and, at  2318 , an IoT device packet is generated containing the IoT device session public key. At  2319 , the IoT device signs the IoT device packet with IoT device private key. At  2320 , the IoT device sends the packet to the IoT hub over the unencrypted channel and, at  2321 , the IoT hub forwards the packet to the IoT service over an encrypted channel. 
     At  2322 , the IoT service verifies the signature of the packet (e.g., using the IoT device public key) and, at  2323 , the IoT service uses the IoT service private key and the IoT device public key to generate the session secret (as described in detail above). At  2324 , the IoT device uses the IoT device private key and IoT service public key to generate the session secret (again, as described above) and, at  2325 , the IoT device generates a random number and encrypts it using the session secret. At  2326 , the IoT service sends the encrypted packet to IoT hub over the encrypted channel. At  2327 , the IoT hub forwards the encrypted packet to the IoT device over the unencrypted channel. At  2328 , the IoT device decrypts the packet using the session secret. 
     Turning to  FIG. 23C , the IoT device re-encrypts the packet using the session secret at  2329  and, at  2330 , the IoT device sends the encrypted packet to the IoT hub over the unencrypted channel. At  2331 , the IoT hub forwards the encrypted packet to the IoT service over the encrypted channel. The IoT service decrypts the packet using the session secret at  2332 . At  2333  the IoT service verifies that the random number matches the random number it sent. The IoT service then sends a packet indicating that pairing is complete at  2334  and all subsequent messages are encrypted using the session secret at  2335 . 
     While a dedicated IoT hub  110  is illustrated in many embodiments above, a dedicated IoT hub hardware platform is not required for complying with the underlying principles of the invention. For example, the various IoT hubs described above may be implemented as software executed within various other networking devices such as iPhones® and Android® devices (e.g., an IoT device App). In fact, the IoT hubs described herein may be implemented on any device capable of communicating with IoT devices (e.g., using BTLE or other local wireless protocol) and establishing a connection over the Internet (e.g., to an IoT service using a WiFi or cellular data connection). 
     Interface and Method for Efficient Communication Between a Microcontroller and a Communication Module 
     As mentioned, in one embodiment, each IoT device includes a secure communication module for establishing a secure communication channel with an IoT service and a microcontroller unit (MCU) which executes program code to perform application-specific functions (e.g., in accordance with the specific functions to be performed by the IoT device). In one embodiment, a serial communication interface is communicatively coupled between the MCU and the secure communication module. 
       FIG. 24  illustrates one particular embodiment in which a serial peripheral interface (SPI)  2410  is used to provide bi-directional communication between the MCU  2401  and secure communication module  2402 . An SPI interface  2410  is a synchronous serial communication interface specification used for short distance communication, primarily in embedded systems. In one embodiment, the MCU  2401  operates as the Master and the secure communication module  2402  operates as a Slave in accordance with the SPI communication protocol. Accordingly, in some embodiments described below, the MCU will simply be referred to as the “Master” and the secure communication module will be referred to as the “Slave.” 
     As used herein the SPI interface  2410  refers to both the SPI bus lines connecting the Master  2401  with the Slave  2402  and the SPI interface circuitry on the Master and Slave (described in greater detail below). The communication bus lines of the SPI interface  2410  include a system clock (SCK) generated by the Master  2401 , a chip select (CS) controlled by the Master  2401 , a Master-out-Slave-In (MOSI) communication line for transmitting data from the Master  2401  to the Slave  2402  and a Master-in-Slave-out (MISO) communication line for transmitting data from the Slave  2402  to the Master  2041 . 
     The standard SPI protocol requires the Master to initiate all communication with the Slave. Thus, to receive data from the Slave, the Master must control the chip select (CS) line and indicate to the slave that it needs data or needs to transmit data. After a period of time (which may be as much as 2 ms), when the Slave is ready to respond, it will send the data. Because of the amount of handshaking and waiting time in order to coordinate the communication between the Master and Slave, the current SPI protocol is inefficient, particularly when large amounts of data need to be streamed between the Master and the Slave. 
     As such, in one embodiment, a control line  2410  is added to improve the speed at which the SPI interface can be run between the Master  2401  and the Slave  2402 . In particular, when either the Master  2401  or the Slave  2402  has data that needs to be transmitted to the other, it pulls the control line  2410  low, informing the other that it is ready to send data. This coordinates all of the transactions on the SPI interface  2410  in a more efficient manner because if the Slave  2402  wants to send data, it pulls the control line  2401  low and, upon seeing that the line is low, the Master  2401  initiates the transaction using the SPI interface  2410 . The Slave  2402  then transmits the data. In one embodiment, the transaction is bi-directional so data can be streamed concurrently in both directions. When the transaction is complete, bother the Master  2401  and the Slave  2402  release the control line  2410 , which goes high again, indicating to both the Master and Slave that either party may initiate a new transaction. 
       FIG. 25  illustrates additional details of one embodiment of the invention including interface circuitry  2550  on the Master  2401  and interface circuitry  2560  on the Slave  2402  which include components such as bus drivers to transmit and receive digital data over the MOSI and MISO bus lines. Control logic  2552 ,  2562  controls the communication as described above by pulling the control line  2410  low when either the Master  2401  or the Slave  2402  needs to initiate a new transaction. In the illustrated embodiment, the control logic  2562  of the Slave is electrically coupled to the base of a first transistor  2402  and the control logic  2552  of the Master  2401  is electrically coupled to the base of a second transistor  2503 . The drain of each transistor is connected to ground (GND) and the source of each transistor is coupled to a pull up resistor  2501  on a line to which a voltage is supplied (V). The transistors  2502 - 2503  may be any type of transistors including bipolar junction transistors (BJTs) or field-effect transistors (FETs). 
     In operation, when neither the Master nor the Slave need to initiate a transaction, the control logic  2552  and  2562  keeps the transistors  2503  and  2502 , respectively, in an off state, thereby pulling the control line  2410  high (i.e., pulled up to a voltage V). When either the Master or the Slave need to initiate a transaction, the control logic  2552 ,  2562  applies a voltage to the base of a respective transistor  2503 ,  2502 , which allows current to flow through the transistor, thereby pulling the control line  2410  to ground. 
     Thus, either the Master  2401  or the Slave  2402  may pull the control line low, indicating that a transaction is in progress. In addition, in one embodiment, neither the Master nor the slave will attempt to initiate a transaction when the control line is pulled low, thereby ensuring coordination between the Master  2401  and Slave  2402 . 
     In one embodiment, this coordination is used to establish a bi-directional streaming interface between the Master  2401  and the Slave  2402  operating at a significantly greater speed than current SPI interfaces. In one embodiment, the Master  2401  and Slave  2402  include small (e.g., 10 Byte) data buffers,  2551  and  2561 , respectively, to buffer data streamed between the Master  2401  and the Slave  2402 . Consequently, when an amount of data greater than the size of the data buffers  2551 ,  2561  needs to be transmitted between the Master and the Slave, the control line  2410  may be pulled and maintained low by the party initiating the transaction to ensure that the other party does not attempt to take control of the interface before the transaction is complete. For example, if the Slave  2402  has 100 Bytes to transmit to the Master  2401 , it may take control by pulling the control line  2410  low, transmit the first 10 Bytes, and keep the control line low  2410  while the Master receives the first 10 Bytes. When the Master indicates that it can accept more data, the Slave  2402  transmits the next 10 Bytes. After the entire 100 Bytes of data has been provided to the Master  2401  in 10 Byte increments, the Slave  2402  releases the control line  2410  (allowing it to be pulled high) to indicate that the Master may take control. The Master may also keep the control line  2410  low while it is receiving and processing each 10 Byte buffer of data. Once it has completed receiving and processing the data, it will release the control line  2410 . 
     In one embodiment, a general purpose input/output (GPIO) line may be shared between the Master  2401  and Slave  2402  to enable this communication. The GPIO line may operate in substantially the same manner as described above—i.e., when one party wants to enter into a transaction, it pulls the GPIO line low informing the other party that a transaction is in process. 
     One embodiment of the invention utilizes a special arrangement of bytes to enable bi-direction communication and signaling between the Master  2401  and the Slave  2402 .  FIG. 26  illustrates an exemplary 10 Byte segment, identified as Bytes  0 - 9 , in which Bytes  0  and  1  are used for error correction and control and Bytes  2 - 9  are used for data. In particular, Byte  0  comprises a checksum over the Bytes  1 - 9 , which may be used by the receiving party to detect transmission errors. For example, the receiving party may calculate its own checksum over Bytes  1 - 9  and compare the result with the checksum in Byte  0 . If the result is the same, then it may be assumed that no errors were introduced. If the checksum is not the same, then the receiving party may request retransmission of the 10 Byte segment. 
     In one embodiment, Byte  1  is arranged into a predetermined sequence of bits  2601  (e.g., 001 in the example) used by the receiving party to identify the beginning of the data sequence. In one embodiment, the fourth bit  2602  is used to indicate whether the transmission is the end of a data packet. For example, in as discussed above for a data packet of 100 Bytes, the value  2602  may be set to 1 when the last 10 Bytes is transmitted. The receiving party will then know when the packet transmission is complete. In one embodiment, the next four bytes  2603  (identified as nnnn) are set to indicate the number of Bytes of valid data stored in Bytes  2 - 9 . For example, if only Byte  2  includes valid data, then the value of  2603  may be 0001; if both Bytes  2  and  3  include valid data, then the value of  2603  may be 0010, and so on. The receiving side will then process only the valid data and ignore the rest. In one embodiment, whenever a transaction occurs between the Master and the Slave, the 10 Byte segment is transmitted in both directions (i.e., one from the Master to the Slave and one from the Slave to the Master). However, if a party has no data to send, it will simply set the nnnn value  2603  equal to 0000. If both parties have data to send then they will each send the data concurrently, and indicate the number of valid Bytes by adjusting the nnnn value  2603 . 
     The above techniques significantly increase the speed at which current SPI interfaces are capable of running, establishing a bi-directional streaming protocol over standard SPI bus lines. Using these techniques, an application  2503  running on the MCU  2401  can efficiently stream data to the IoT service  120  and, at the same time, the IoT service can efficiently stream data to the application  2403 . In addition, in one embodiment, the secure communication module  2402  establishes a secure communication channel with the IoT service  120  using the various techniques described above with respect to  FIGS. 16A-23C . 
     Integrated Development Tool for an Internet of Things (IoT) System 
     One embodiment of the invention includes an integrated development tool to allow IoT developers to readily design new IoT devices, services, and client apps for end users. In particular, in one embodiment, the integrated development tool allows the developer to indicate the input/output functions to be performed by each IoT device, the GUI features to be available to end users, and the back-end functions to be performed by the IoT service. In response, the integrated development tool generates a first profile for the IoT device, a second profile for a client device app, and a third profile for the IoT service to realize an end-to-end, fully-functional IoT implementation with limited effort. 
       FIG. 27  illustrates one embodiment of an integrated development tool platform  2701  which includes a development application  2720  with a graphical user interface  2721  usable by a developer to design new IoT implementations. In one embodiment, the integrated development tool (IDT) platform  2701  comprises a computer system with a storage device and memory for storing program code of the development application  2720  and a processor for processing the program code during runtime. In addition, the various other modules illustrated in  FIG. 27  (e.g.,  2730 - 2732 ) may be implemented as program code executed by the processor. 
     A development database  2710  is loaded and continually updated with data related to different IoT device configurations, user interface features for client-side apps, and IoT service configurations. For example, the development database  2710  may include data related to different types of input/output (I/O) functions to be performed by each of the IoT devices  101 - 102  including, but not limited to analog-to-digital (A/D) functions (e.g., capturing an analog voltage level), digital-to-analog (D/A) functions (e.g., providing an analog voltage output), binary on/off functions (e.g., unlocking a door, triggering an alarm, turning on a light, etc), and various General Purpose I/O (GPIO) functions. 
     In addition, as discussed below, the developer may specify whether the IoT device  102  is to be designed with a stand-alone secure communication module  2402  or whether the IoT device  101  is to be designed with both a secure communication nodule  2402  and MCU  2401  (e.g., interconnected via an SPI interface as discussed above). A stand-alone implementation may be used for relatively simpler IoT implementations such as those which perform simple on/off functions (e.g., a switch integrated on a lightbulb) whereas the MCU implementation may be used for more complex data collection and monitoring (e.g., a remotely-controllable video camera triggered by a motion sensor). 
     In one embodiment, once the developer has specified the particular I/O functions to be performed by an IoT device via the development application  2720 , an IoT device engine  2730  uses the configuration data provided from the development application to generate an IoT device profile  2740 , specifying the configuration parameters for the secure communication module  2402 . This may include, for example, the mode that the secure communication module is in, including whether the secure communication module  2402  is in a stand-alone mode or coupled to an MCU  2401 . If in stand-alone mode, the IoT device profile  2740  configures the various I/O lines  2407  of the secure communication module  2402  to perform the functions required by the IoT device  102 . If used with an MCU  2401 , the IoT device profile  2740  may configure the I/O lines  2407  of the secure communication module  2402  and the I/O lines  2408  of the MCU and may also specify how the secure communication module  2402  is to interact with the MCU  2401  (e.g., communicating over an SPI bus to exchange data and commands with the application executed on the MCU as described above). 
     In one embodiment, the IoT device profile  2740  may be loaded into a non-volatile memory on the secure communication module  2402  (e.g., Flash memory) to implement the IoT functions (see, e.g.,  FIG. 2  showing app code  203 , library code  202 , and communication stack code  201  executed by the low power uC  200 ). In alternate embodiments, the IoT device profile  2740  may be used to configure an application-specific integrated circuit or field-programmable gate array (FPGA). The underlying principles of the invention are not limited to any particular configuration for secure communication module  2402 . 
     In addition to configuring the IoT device, in one embodiment, once the developer has specified the particular I/O functions to be performed by an IoT device via the development application  2720 , an IoT device engine  2730  uses the configuration data from the development application to generate a user experience (UX) profile  2741  to be used to implement the IoT app or application on the client device  611 . The UX profile, for example, may specify various graphical I/O elements to be displayed within the GUI of the IoT app or application and the configurations to be used for those graphical I/O elements. For example, if the IoT device  102  is a light switch (or other simple on/off device such as a door lock), then the UX profile may include a simple on/off switch to control the IoT device  102 . If the IoT device  101  is a video capture device then the UX profile may specify a graphical element to cause video to be displayed on the client  611  and the specific parameters for displaying the video (e.g., scaling to be used, location on the client display, etc). A virtually unlimited number of different user interface features may be specified by the UX profile while still complying with the underlying principles of the invention. 
     In addition, in one embodiment, an IoT service engine  2732  generates a cloud API profile  2742  to accommodate the service-side requirements of the new IoT devices  101 - 102 . This may include, for example, the manner in which the IoT service  120  is to exchange commands and data with the new IoT devices and/or notifications to be sent to the user&#39;s client device  611  in response to data received from the IoT devices. For example, if the IoT device is a door lock, then the cloud API profile may specify that a notification is to be sent to the client device  611  whenever the door is opened and the user is not home. In addition, the cloud API profile  2742  may specify the commands to be used to control the new IoT devices. In one embodiment, the cloud API profile  2742  specifies the manner in which the IoT service  120  is to communicate with external IoT services such as the IoT services run by the designer of the new IoT devices  101 - 102  (e.g., exposing an API to the external IoT services). 
     A method implemented by an integrated development tool for an IoT system is illustrated in  FIG. 28 . The method may be implemented within the context of the system architectures described above, but is not limited to any particular system architecture. 
     At  2801 , the designer enters parameters for the new IoT device via the GUI of the development application. This may include, for example, the I/O functions to be performed by the IoT device and the manner in which the IoT device is to interact with the IoT service. At  2802 , using data from the development application, the IoT device engine generates an IoT device profile. In addition to the I/O function specification, this may include an indication as to whether the secure communication module is in stand-alone mode or used with an MCU. At  2803 , the IoT device profile is applied to the IoT device. In one embodiment, this involves copying the program code to a non-volatile storage on the IoT device. 
     At  2804 , using data from the development application, the client app engine generates a UX profile specifying (among other things) the user interface to be displayed on the client when interacting with the new IoT devices. At  2805 , the UX profile is applied to the client. 
     At  2806 , using data from the development application, the IoT service engine generates a cloud API profile specifying the manner in which the IoT service is to interoperate with the new IoT devices, the client device and/or any external IoT services. For example, as described above, the IoT service may expose an API to enable communication with one or more external IoT services. At  2805 , the cloud API profile is applied to the IoT cloud service. 
     Thus, using the integrated development techniques described herein, a developer can concurrently program a new IoT device, an IoT service, and a user app, thereby saving a significant amount of time and effort compared with current implementations in which each component must be independently programmed and configured. 
     Embodiments of the invention may include various steps, which have been described above. The steps may be embodied in machine-executable instructions which may be used to cause a general-purpose or special-purpose processor to perform the steps. Alternatively, these steps may be performed by specific hardware components that contain hardwired logic for performing the steps, or by any combination of programmed computer components and custom hardware components. 
     As described herein, instructions may refer to specific configurations of hardware such as application specific integrated circuits (ASICs) configured to perform certain operations or having a predetermined functionality or software instructions stored in memory embodied in a non-transitory computer readable medium. Thus, the techniques shown in the figures can be implemented using code and data stored and executed on one or more electronic devices (e.g., an end station, a network element, etc.). Such electronic devices store and communicate (internally and/or with other electronic devices over a network) code and data using computer machine-readable media, such as non-transitory computer machine-readable storage media (e.g., magnetic disks; optical disks; random access memory; read only memory; flash memory devices; phase-change memory) and transitory computer machine-readable communication media (e.g., electrical, optical, acoustical or other form of propagated signals—such as carrier waves, infrared signals, digital signals, etc.). In addition, such electronic devices typically include a set of one or more processors coupled to one or more other components, such as one or more storage devices (non-transitory machine-readable storage media), user input/output devices (e.g., a keyboard, a touchscreen, and/or a display), and network connections. The coupling of the set of processors and other components is typically through one or more busses and bridges (also termed as bus controllers). The storage device and signals carrying the network traffic respectively represent one or more machine-readable storage media and machine-readable communication media. Thus, the storage device of a given electronic device typically stores code and/or data for execution on the set of one or more processors of that electronic device. Of course, one or more parts of an embodiment of the invention may be implemented using different combinations of software, firmware, and/or hardware. 
     Throughout this detailed description, for the purposes of explanation, numerous specific details were set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the invention may be practiced without some of these specific details. In certain instances, well known structures and functions were not described in elaborate detail in order to avoid obscuring the subject matter of the present invention. Accordingly, the scope and spirit of the invention should be judged in terms of the claims which follow.