Maxim Integrated / Mbed OS MAXREFDES155#

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/SensorNode.cpp@17:5926077e5345, 2019-10-04 (annotated)

Committer:
IanBenzMaxim
Date:
Fri Oct 04 12:10:11 2019 -0500
Revision:
17:5926077e5345
Parent:
16:a004191a79ab 
Set pin maps through the mbed configuration system. Added support for MAX32625MBED target. Updated mbed-os to version 5.7.7 for MAX32625 I2C fixes. Consolidated simplelink hook definitions.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
IanBenzMaxim 0:33d4e66780c0 1 /*******************************************************************************
IanBenzMaxim 16:a004191a79ab 2 * Copyright (C) Maxim Integrated Products, Inc., All Rights Reserved.
IanBenzMaxim 0:33d4e66780c0 3 *
IanBenzMaxim 0:33d4e66780c0 4 * Permission is hereby granted, free of charge, to any person obtaining a
IanBenzMaxim 0:33d4e66780c0 5 * copy of this software and associated documentation files (the "Software"),
IanBenzMaxim 0:33d4e66780c0 6 * to deal in the Software without restriction, including without limitation
IanBenzMaxim 0:33d4e66780c0 7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
IanBenzMaxim 0:33d4e66780c0 8 * and/or sell copies of the Software, and to permit persons to whom the
IanBenzMaxim 0:33d4e66780c0 9 * Software is furnished to do so, subject to the following conditions:
IanBenzMaxim 0:33d4e66780c0 10 *
IanBenzMaxim 0:33d4e66780c0 11 * The above copyright notice and this permission notice shall be included
IanBenzMaxim 0:33d4e66780c0 12 * in all copies or substantial portions of the Software.
IanBenzMaxim 0:33d4e66780c0 13 *
IanBenzMaxim 0:33d4e66780c0 14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
IanBenzMaxim 0:33d4e66780c0 15 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
IanBenzMaxim 0:33d4e66780c0 16 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IanBenzMaxim 0:33d4e66780c0 17 * IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
IanBenzMaxim 0:33d4e66780c0 18 * OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
IanBenzMaxim 0:33d4e66780c0 19 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
IanBenzMaxim 0:33d4e66780c0 20 * OTHER DEALINGS IN THE SOFTWARE.
IanBenzMaxim 0:33d4e66780c0 21 *
IanBenzMaxim 0:33d4e66780c0 22 * Except as contained in this notice, the name of Maxim Integrated
IanBenzMaxim 0:33d4e66780c0 23 * Products, Inc. shall not be used except as stated in the Maxim Integrated
IanBenzMaxim 0:33d4e66780c0 24 * Products, Inc. Branding Policy.
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IanBenzMaxim 0:33d4e66780c0 26 * The mere transfer of this software does not imply any licenses
IanBenzMaxim 0:33d4e66780c0 27 * of trade secrets, proprietary technology, copyrights, patents,
IanBenzMaxim 0:33d4e66780c0 28 * trademarks, maskwork rights, or any other form of intellectual
IanBenzMaxim 0:33d4e66780c0 29 * property whatsoever. Maxim Integrated Products, Inc. retains all
IanBenzMaxim 0:33d4e66780c0 30 * ownership rights.
IanBenzMaxim 0:33d4e66780c0 31 *******************************************************************************/
IanBenzMaxim 0:33d4e66780c0 32
IanBenzMaxim 0:33d4e66780c0 33 #include <string>
IanBenzMaxim 16:a004191a79ab 34 #include <MaximInterfaceCore/HexString.hpp>
IanBenzMaxim 16:a004191a79ab 35 #include <mbed-os/drivers/I2C.h>
IanBenzMaxim 0:33d4e66780c0 36 #include "SensorNode.hpp"
IanBenzMaxim 0:33d4e66780c0 37
IanBenzMaxim 16:a004191a79ab 38 #define TRY MaximInterfaceCore_TRY
IanBenzMaxim 16:a004191a79ab 39 #define TRY_VALUE MaximInterfaceCore_TRY_VALUE
IanBenzMaxim 16:a004191a79ab 40
IanBenzMaxim 16:a004191a79ab 41 using namespace MaximInterfaceCore;
IanBenzMaxim 16:a004191a79ab 42 using MaximInterfaceDevices::DS2476;
IanBenzMaxim 16:a004191a79ab 43 using MaximInterfaceDevices::DS28C36;
IanBenzMaxim 13:6a6225690c2e 44
IanBenzMaxim 0:33d4e66780c0 45 // I2C address of the MLX90614.
IanBenzMaxim 0:33d4e66780c0 46 static const uint8_t mlx90614Addr = 0xB4;
IanBenzMaxim 0:33d4e66780c0 47
IanBenzMaxim 16:a004191a79ab 48 SensorNode::SensorNode(Sleep & sleep, I2CMaster & i2c, DS2476 & ds2476)
IanBenzMaxim 16:a004191a79ab 49 : i2c(&i2c), ds28c36(sleep, i2c), ds2476(&ds2476) {}
IanBenzMaxim 13:6a6225690c2e 50
IanBenzMaxim 16:a004191a79ab 51 SensorNode::State SensorNode::detect() {
IanBenzMaxim 16:a004191a79ab 52 if (Result<DS28C36::Page::array> page =
IanBenzMaxim 16:a004191a79ab 53 ds28c36.readMemory(DS28C36::romOptionsPage)) {
IanBenzMaxim 16:a004191a79ab 54 const DS28C36::RomOptions romOptions(page.value());
IanBenzMaxim 16:a004191a79ab 55 copy(romOptions.romId(), make_span(romId));
IanBenzMaxim 16:a004191a79ab 56 copy(romOptions.manId(), make_span(manId));
IanBenzMaxim 16:a004191a79ab 57 } else {
IanBenzMaxim 16:a004191a79ab 58 return Disconnected;
IanBenzMaxim 13:6a6225690c2e 59 }
IanBenzMaxim 13:6a6225690c2e 60
IanBenzMaxim 16:a004191a79ab 61 if (!valid(romId)) {
IanBenzMaxim 16:a004191a79ab 62 return Disconnected;
IanBenzMaxim 13:6a6225690c2e 63 }
IanBenzMaxim 13:6a6225690c2e 64
IanBenzMaxim 16:a004191a79ab 65 {
IanBenzMaxim 16:a004191a79ab 66 const Result<void> result = authenticate();
IanBenzMaxim 16:a004191a79ab 67 if (!result) {
IanBenzMaxim 16:a004191a79ab 68 return (result.error() == DS28C36::AuthenticationError) ? Invalid
IanBenzMaxim 16:a004191a79ab 69 : Disconnected;
IanBenzMaxim 16:a004191a79ab 70 }
IanBenzMaxim 13:6a6225690c2e 71 }
IanBenzMaxim 13:6a6225690c2e 72
IanBenzMaxim 16:a004191a79ab 73 const Result<bool> laserEnabled = getLaserEnabled();
IanBenzMaxim 16:a004191a79ab 74 return laserEnabled
IanBenzMaxim 16:a004191a79ab 75 ? (laserEnabled.value() ? ValidLaserEnabled : ValidLaserDisabled)
IanBenzMaxim 16:a004191a79ab 76 : Disconnected;
IanBenzMaxim 0:33d4e66780c0 77 }
IanBenzMaxim 0:33d4e66780c0 78
IanBenzMaxim 16:a004191a79ab 79 Result<double> SensorNode::readTemp(TempStyle style) {
IanBenzMaxim 13:6a6225690c2e 80 uint8_t data[2];
IanBenzMaxim 13:6a6225690c2e 81 switch (style) {
IanBenzMaxim 13:6a6225690c2e 82 case ObjectTemp:
IanBenzMaxim 13:6a6225690c2e 83 default:
IanBenzMaxim 13:6a6225690c2e 84 data[0] = 0x07;
IanBenzMaxim 13:6a6225690c2e 85 break;
IanBenzMaxim 0:33d4e66780c0 86
IanBenzMaxim 13:6a6225690c2e 87 case AmbientTemp:
IanBenzMaxim 13:6a6225690c2e 88 data[0] = 0x06;
IanBenzMaxim 13:6a6225690c2e 89 break;
IanBenzMaxim 13:6a6225690c2e 90 }
IanBenzMaxim 16:a004191a79ab 91 TRY(i2c->writePacket(mlx90614Addr, make_span(data, 1),
IanBenzMaxim 16:a004191a79ab 92 I2CMaster::StopOnError));
IanBenzMaxim 16:a004191a79ab 93 TRY(i2c->readPacket(mlx90614Addr, data, I2CMaster::Stop));
IanBenzMaxim 16:a004191a79ab 94 return ((static_cast<unsigned int>(data[1]) << 8) | data[0]) * 0.02 - 273.15;
IanBenzMaxim 0:33d4e66780c0 95 }
IanBenzMaxim 0:33d4e66780c0 96
IanBenzMaxim 16:a004191a79ab 97 Result<void> SensorNode::authenticate() {
IanBenzMaxim 13:6a6225690c2e 98 // Compute slave secret on coprocessor.
IanBenzMaxim 16:a004191a79ab 99 DS28C36::PageAuthenticationData message;
IanBenzMaxim 16:a004191a79ab 100 message.setPageNum(0);
IanBenzMaxim 16:a004191a79ab 101 if (const Result<DS28C36::Page::array> page =
IanBenzMaxim 16:a004191a79ab 102 ds28c36.readMemory(message.pageNum())) {
IanBenzMaxim 16:a004191a79ab 103 message.setPage(page.value());
IanBenzMaxim 16:a004191a79ab 104 } else {
IanBenzMaxim 16:a004191a79ab 105 return page.error();
IanBenzMaxim 16:a004191a79ab 106 }
IanBenzMaxim 16:a004191a79ab 107 message.setRomId(romId);
IanBenzMaxim 16:a004191a79ab 108 message.setManId(manId);
IanBenzMaxim 16:a004191a79ab 109 TRY(ds2476->writeBuffer(message.result()));
IanBenzMaxim 16:a004191a79ab 110 TRY(ds2476->computeSha2UniqueSecret(DS2476::SecretNumA));
IanBenzMaxim 13:6a6225690c2e 111
IanBenzMaxim 13:6a6225690c2e 112 // Compute HMAC on coprocessor.
IanBenzMaxim 13:6a6225690c2e 113 // ROM ID, Page 0, and MAN ID are already in message.
IanBenzMaxim 16:a004191a79ab 114 TRY(ds2476->readRng(message.challenge()));
IanBenzMaxim 16:a004191a79ab 115 TRY(ds2476->writeBuffer(message.result()));
IanBenzMaxim 16:a004191a79ab 116 DS2476::Page::array computedHmac;
IanBenzMaxim 16:a004191a79ab 117 TRY_VALUE(computedHmac, ds2476->computeSha2Hmac());
IanBenzMaxim 13:6a6225690c2e 118
IanBenzMaxim 13:6a6225690c2e 119 // Compute HMAC on device.
IanBenzMaxim 16:a004191a79ab 120 TRY(ds28c36.writeBuffer(message.challenge()));
IanBenzMaxim 16:a004191a79ab 121 DS28C36::Page::array deviceHmac;
IanBenzMaxim 16:a004191a79ab 122 TRY_VALUE(deviceHmac, ds28c36.computeAndReadPageAuthentication(
IanBenzMaxim 16:a004191a79ab 123 message.pageNum(), DS28C36::SecretNumA));
IanBenzMaxim 13:6a6225690c2e 124
IanBenzMaxim 16:a004191a79ab 125 return (computedHmac == deviceHmac) ? makeResult(none)
IanBenzMaxim 16:a004191a79ab 126 : DS28C36::AuthenticationError;
IanBenzMaxim 0:33d4e66780c0 127 }
IanBenzMaxim 0:33d4e66780c0 128
IanBenzMaxim 16:a004191a79ab 129 Result<void> SensorNode::setLaserEnabled(bool enabled,
IanBenzMaxim 16:a004191a79ab 130 const PrintHandler & print) {
IanBenzMaxim 13:6a6225690c2e 131 if (print) {
IanBenzMaxim 13:6a6225690c2e 132 print((std::string(enabled ? "Enabling" : "Disabling") + " laser").c_str());
IanBenzMaxim 13:6a6225690c2e 133 }
IanBenzMaxim 13:6a6225690c2e 134
IanBenzMaxim 13:6a6225690c2e 135 // Compute write HMAC.
IanBenzMaxim 13:6a6225690c2e 136 // ROM ID and MAN ID are already in message.
IanBenzMaxim 13:6a6225690c2e 137 if (print) {
IanBenzMaxim 13:6a6225690c2e 138 print("Reading GPIO Control page");
IanBenzMaxim 13:6a6225690c2e 139 print((std::string(
IanBenzMaxim 13:6a6225690c2e 140 "Modify copy of GPIO Control page to set GPIO B state to ") +
IanBenzMaxim 16:a004191a79ab 141 (enabled ? "conducting" : "high-impedance"))
IanBenzMaxim 16:a004191a79ab 142 .c_str());
IanBenzMaxim 13:6a6225690c2e 143 }
IanBenzMaxim 16:a004191a79ab 144 DS28C36::WriteAuthenticationData message;
IanBenzMaxim 16:a004191a79ab 145 message.setPageNum(DS28C36::gpioControlPage);
IanBenzMaxim 16:a004191a79ab 146 if (const Result<DS28C36::Page::array> oldPage =
IanBenzMaxim 16:a004191a79ab 147 ds28c36.readMemory(message.pageNum())) {
IanBenzMaxim 16:a004191a79ab 148 message.setOldPage(oldPage.value());
IanBenzMaxim 16:a004191a79ab 149 } else {
IanBenzMaxim 16:a004191a79ab 150 return oldPage.error();
IanBenzMaxim 16:a004191a79ab 151 }
IanBenzMaxim 16:a004191a79ab 152 message.setNewPage(message.oldPage());
IanBenzMaxim 16:a004191a79ab 153 DS28C36::GpioControl(message.newPage()).setPiobConducting(enabled);
IanBenzMaxim 16:a004191a79ab 154 message.setRomId(romId);
IanBenzMaxim 16:a004191a79ab 155 message.setManId(manId);
IanBenzMaxim 13:6a6225690c2e 156 if (print) {
IanBenzMaxim 13:6a6225690c2e 157 print(("Creating HMAC message (ROM ID | Old Page Data | New Page Data | "
IanBenzMaxim 13:6a6225690c2e 158 "Page # | MAN ID): " +
IanBenzMaxim 16:a004191a79ab 159 toHexString(message.result()))
IanBenzMaxim 16:a004191a79ab 160 .c_str());
IanBenzMaxim 13:6a6225690c2e 161 print("Writing HMAC message to DS2476 buffer");
IanBenzMaxim 13:6a6225690c2e 162 }
IanBenzMaxim 16:a004191a79ab 163 TRY(ds2476->writeBuffer(message.result()));
IanBenzMaxim 16:a004191a79ab 164 DS2476::Page::array hmac;
IanBenzMaxim 16:a004191a79ab 165 TRY_VALUE(hmac, ds2476->computeSha2Hmac());
IanBenzMaxim 13:6a6225690c2e 166
IanBenzMaxim 13:6a6225690c2e 167 if (print) {
IanBenzMaxim 13:6a6225690c2e 168 print(("DS2476 computes write authentication HMAC from slave secret "
IanBenzMaxim 13:6a6225690c2e 169 "(Secret S) and message in buffer: " +
IanBenzMaxim 16:a004191a79ab 170 toHexString(hmac))
IanBenzMaxim 16:a004191a79ab 171 .c_str());
IanBenzMaxim 13:6a6225690c2e 172 print("Write authentication HMAC is written to DS28C36 buffer");
IanBenzMaxim 13:6a6225690c2e 173 print("DS28C36 computes an HMAC to compare to the write authentication "
IanBenzMaxim 13:6a6225690c2e 174 "HMAC after receiving Page # and New Page Data");
IanBenzMaxim 13:6a6225690c2e 175 }
IanBenzMaxim 13:6a6225690c2e 176
IanBenzMaxim 13:6a6225690c2e 177 // Write page data.
IanBenzMaxim 16:a004191a79ab 178 TRY(ds28c36.writeBuffer(hmac));
IanBenzMaxim 16:a004191a79ab 179 TRY(ds28c36.authenticatedSha2WriteMemory(
IanBenzMaxim 16:a004191a79ab 180 message.pageNum(), DS28C36::SecretNumA, message.newPage()));
IanBenzMaxim 13:6a6225690c2e 181 if (print) {
IanBenzMaxim 13:6a6225690c2e 182 print("DS28C36 updates page data which changes GPIO B state");
IanBenzMaxim 13:6a6225690c2e 183 print((std::string("Laser is now ") + (enabled ? "enabled" : "disabled"))
IanBenzMaxim 13:6a6225690c2e 184 .c_str());
IanBenzMaxim 13:6a6225690c2e 185 }
IanBenzMaxim 16:a004191a79ab 186 return none;
IanBenzMaxim 0:33d4e66780c0 187 }
IanBenzMaxim 0:33d4e66780c0 188
IanBenzMaxim 16:a004191a79ab 189 Result<bool> SensorNode::getLaserEnabled() {
IanBenzMaxim 16:a004191a79ab 190 DS28C36::Page::array page;
IanBenzMaxim 16:a004191a79ab 191 TRY_VALUE(page, ds28c36.readMemory(DS28C36::gpioControlPage));
IanBenzMaxim 16:a004191a79ab 192 return DS28C36::GpioControl(page).piobConducting();
IanBenzMaxim 0:33d4e66780c0 193 }