DeepCover Embedded Security in IoT: Public-key Secured Data Paths

Dependencies:   MaximInterface

The MAXREFDES155# is an internet-of-things (IoT) embedded-security reference design, built to authenticate and control a sensing node using elliptic-curve-based public-key cryptography with control and notification from a web server.

The hardware includes an ARM® mbed™ shield and attached sensor endpoint. The shield contains a DS2476 DeepCover® ECDSA/SHA-2 coprocessor, Wifi communication, LCD push-button controls, and status LEDs. The sensor endpoint is attached to the shield using a 300mm cable and contains a DS28C36 DeepCover ECDSA/SHA-2 authenticator, IR-thermal sensor, and aiming laser for the IR sensor. The MAXREFDES155# is equipped with a standard Arduino® form-factor shield connector for immediate testing using an mbed board such as the MAX32600MBED#. The combination of these two devices represent an IoT device. Communication to the web server is accomplished with the shield Wifi circuitry. Communication from the shield to the attached sensor module is accomplished over I2C . The sensor module represents an IoT endpoint that generates small data with a requirement for message authenticity/integrity and secure on/off operational control.

The design is hierarchical with each mbed platform and shield communicating data from the sensor node to a web server that maintains a centralized log and dispatches notifications as necessary. The simplicity of this design enables rapid integration into any star-topology IoT network to provide security with the low overhead and cost provided by the ECDSA-P256 asymmetric-key and SHA-256 symmetric-key algorithms.

More information about the MAXREFDES155# is available on the Maxim Integrated website.

src/CC3100.hpp

Committer:
IanBenzMaxim
Date:
2019-10-04
Revision:
17:5926077e5345
Parent:
16:a004191a79ab

File content as of revision 17:5926077e5345:

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#ifndef CC3100_HPP
#define CC3100_HPP

#include <stdint.h>
#include <stddef.h>
#include <ctime>
#include <string>
#include <mbed-os/drivers/DigitalOut.h>
#include <mbed-os/drivers/SPI.h>
#include <mbed-os/features/netsocket/NetworkStack.h>
#include <mbed-os/features/netsocket/WiFiInterface.h>

/// CC3100 Wi-Fi station interface for mbed using SPI.
class CC3100 : public NetworkStack, public WiFiInterface {
public:
  /// SPI bus interface.
  class SPI {
  public:
    SPI(PinName mosi, PinName miso, PinName sclk, PinName ssel);

    void transfer(const uint8_t * txData, size_t dataSize, uint8_t * rxData);

  private:
    mbed::SPI spi;
    mbed::DigitalOut cs;
  };

  /// CC3100 device state.
  enum State {
    Stopped,
    Disconnected,
    ConnectedWithoutIp,
    Connected,
    Pinging
  };

  /// @brief
  /// Result code occurring when the CC3100 is in an invalid state to perform
  /// an operation.
  static const int invalidState = -1;

  /// Retrieve the singleton instance.
  static CC3100 & instance();

  /// Current state of the CC3100.
  State state() const;

  /// Start the CC3100 so that nework functionality is available.
  int start();

  /// Stop the CC3100 and enter a low power state.
  int stop();

  /// Update the networking stack. Should be called regularly to dispatch events.
  void update();

  /// Set the current date and time.
  int setDateTime(const std::tm & dateTime);

  // WiFi station functionality

  virtual int set_credentials(const char * ssid, const char * pass,
                              nsapi_security_t security = NSAPI_SECURITY_NONE);

  virtual int set_channel(uint8_t channel) {
    this->channel = channel;
    return 0;
  }

  virtual int8_t get_rssi() { return 0; } // Not implemented

  virtual int connect(const char * ssid, const char * pass,
                      nsapi_security_t security = NSAPI_SECURITY_NONE,
                      uint8_t channel = 0);

  virtual int connect() {
    return connect(ssid.c_str(), pass.c_str(), security, channel);
  }

  int connect(const char * ssid, const char * username, const char * password);

  virtual int disconnect();

  virtual int scan(WiFiAccessPoint * res, unsigned count) {
    // Not implemented
    return invalidState;
  }

  // Network functionality
  virtual const char * get_ip_address() { return NULL; } // Not implemented

  virtual int gethostbyname(const char * host, SocketAddress * address,
                            nsapi_version_t version = NSAPI_UNSPEC);

  int ping(const SocketAddress & address);
  
  virtual NetworkStack * get_stack() { return this; }

  // Socket functionality

  virtual int socket_open(nsapi_socket_t * handle, nsapi_protocol_t proto);

  int socket_set_cert_path(nsapi_socket_t handle, const char * certPath);

  virtual int socket_close(nsapi_socket_t handle);

  virtual int socket_bind(nsapi_socket_t handle, const SocketAddress & address);

  virtual int socket_listen(nsapi_socket_t handle, int backlog);

  virtual int socket_connect(nsapi_socket_t handle,
                             const SocketAddress & address);

  virtual int socket_accept(nsapi_socket_t server, nsapi_socket_t * handle,
                            SocketAddress * address = 0) {
    // Not implemented
    return invalidState;
  }

  virtual int socket_send(nsapi_socket_t handle, const void * data,
                          unsigned size);

  virtual int socket_recv(nsapi_socket_t handle, void * data, unsigned size);

  virtual int socket_sendto(nsapi_socket_t handle,
                            const SocketAddress & address, const void * data,
                            unsigned size) {
    // Not implemented
    return invalidState;
  }

  virtual int socket_recvfrom(nsapi_socket_t handle, SocketAddress * address,
                              void * buffer, unsigned size) {
    // Not implemented
    return invalidState;
  }

  virtual void socket_attach(nsapi_socket_t handle, void (*callback)(void *),
                             void * data) {
    // Not implemented
  }

private:
  SPI spi;

  std::string ssid;
  std::string pass;
  nsapi_security_t security;
  uint8_t channel;

  CC3100();

  // Uncopyable
  CC3100(const CC3100 &);
  const CC3100 & operator=(const CC3100 &);
};

#endif