MAXREFDES143#: DeepCover Embedded Security in IoT Authenticated Sensing & Notification

Dependencies:   MaximInterface mbed

The MAXREFDES143# is an Internet of Things (IoT) embedded security reference design, built to protect an industrial sensing node by means of authentication and notification to a web server. The hardware includes a peripheral module representing a protected sensor node monitoring operating temperature and remaining life of a filter (simulated through ambient light sensing) and an mbed shield representing a controller node responsible for monitoring one or more sensor nodes. The design is hierarchical with each controller node communicating data from connected sensor nodes to a web server that maintains a centralized log and dispatches notifications as necessary. The mbed shield contains a Wi-Fi module, a DS2465 coprocessor with 1-Wire® master function, an LCD, LEDs, and pushbuttons. The protected sensor node contains a DS28E15 authenticator, a DS7505 temperature sensor, and a MAX44009 light sensor. The mbed shield communicates to a web server by the onboard Wi-Fi module and to the protected sensor node with I2C and 1-Wire. The MAXREFDES143# is equipped with a standard shield connector for immediate testing using an mbed board such as the MAX32600MBED#. The simplicity of this design enables rapid integration into any star-topology IoT network requiring the heightened security with low overhead provided by the SHA-256 symmetric-key algorithm.

More information about the MAXREFDES143# is available on the Maxim Integrated website.

SensorNode.hpp

Committer:
IanBenzMaxim
Date:
19 months ago
Revision:
35:3d414ba9ab6c
Parent:
32:0a09505a656d

File content as of revision 35:3d414ba9ab6c:

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#ifndef SENSORNODE_HPP
#define SENSORNODE_HPP

#include <stdint.h>
#include <MaximInterface/Devices/DS28E15_22_25.hpp>
#include <MaximInterface/Utilities/RomId.hpp>
#include <MaximInterface/Utilities/ManId.hpp>
#include "DS7505.hpp"
#include "MAX44009.hpp"

class SensorData;
namespace MaximInterface { class DS2465; }
namespace mbed { class I2C; }

/// Interface to the Authenticated Sensor Node peripheral board.
class SensorNode {
public:
  enum State {
    UnableToCommunicate, ///< I2C or 1-Wire communication failure.
    NotProvisioned,      ///< DS28E15 has not been provisioned.
    NotAuthentic,        ///< DS28E15 is not authentic.
    Authentic            ///< DS218E15 is authentic.
  };

  /// @param i2c Configured I2C communication interface.
  /// @param ds7505_i2c_addr I2C bus address of the DS7505 in mbed format.
  /// @param max44009_i2c_addr I2C bus address of the MAX44009 in mbed format.
  /// @param ds2465 Interface to DS2465 on the Controller.
  SensorNode(mbed::I2C & i2c, uint8_t ds7505_i2c_addr,
             uint8_t max44009_i2c_addr, MaximInterface::DS2465 & ds2465);

  /// Detect if an authentic Sensor Node is connected.
  /// @param userEntropy Additional entropy to supply to the RNG.
  /// @returns Authentic on success.
  State detect(unsigned int userEntropy);

  /// Read the current temperature and filter life measurements with authentication.
  /// @param userEntropy Additional entropy to supply to the RNG.
  /// @param sensorData Measurements output location.
  /// @returns Authentic on success.
  State authenticatedReadSensorData(unsigned int userEntropy,
                                    SensorData & sensorData);

  /// Reads the current temperature and filter life measurements.
  /// @param sensorData Measurements output location.
  /// @returns True on success or false if unable to communicate with a sensor.
  bool readSensorData(SensorData & sensorData);

  /// Get the ROM ID for this sensor node.
  const MaximInterface::RomId romId() const { return romId_; }

  /// Get the initial lux measurement for this sensor node.
  double initialLux() const { return initialLux_; }

  // Grant access to hardware interfaces for provisioning.
  friend bool provisionCoprocessor(MaximInterface::DS2465 & ds2465);
  friend bool provisionSensorNode(SensorNode & sensorNode, bool validSecret);

private:
  /// Authenticated data stored in DS28E15.
  struct AuthData {
    static const uint8_t initialFilterLife = 100;
    MaximInterface::DS28E15::Segment segment;
    int pageNum, segmentNum;

    uint8_t & filterLife() { return segment[0]; }
    const uint8_t & filterLife() const { return segment[0]; }

    AuthData() : pageNum(0), segmentNum(0) { reset(); }

    void reset() {
      segment.fill(0);
      filterLife() = initialFilterLife;
    }
  };

  /// Padding value used in creation of the Slave Secret.
  static const uint8_t defaultPaddingByte = 0x00;

  static const MaximInterface::ManId manId;

  /// Indicates hardware RNG is initialized.
  static bool rngInitialized;
  // Initialize the hardware RNG.
  static void initializeRng();

  /// Initial lux measurement taken on initialization.
  /// Assumed to be the maximum intensity that will be observed.
  double initialLux_;

  /// Authenticated data stored on the DS28E15.
  AuthData authData;

  // Hardware interfaces
  MaximInterface::DS2465 & ds2465; ///< Interface to DS2465 on Controller.
  MaximInterface::DS28E15 ds28e15; ///< DS28E15 for authentication.
  MaximInterface::RomId romId_;
  DS7505 ds7505;     ///< DS7505 temperature sensor.
  MAX44009 max44009; ///< MAX44009 optical light sensor.

  /// Initialize sensors for measurement.
  /// @returns True on success.
  bool initializeSensors();

  /// Select the Slave Secret for this Sensor Node in the Controller.
  /// @returns True on success.
  bool setSecret();

  /// Check if the Sensor Board is provisioned.
  /// @param provisioned True if the sensor board is provisioned.
  /// @returns True if provisioning check was successful.
  bool checkProvisioned(bool & provisioned);

  /// Check if the Sensor Board is authentic.
  /// @param userEntropy Additional entropy to supply to the RNG.
  /// @returns True if the Sensor Board passed the authentication check.
  bool checkAuthentic(unsigned int userEntropy);

  /// Checks if the authenticated data stored in the DS28E15 needs to be updated.
  /// Updates the authenticated data if necessary.
  /// @param sensorData Current sensor data to check.
  /// @returns True on success.
  bool checkAndWriteAuthData(SensorData & sensorData);
};

#endif