Michael Mars, Cloud IoT Architect at Softimize.co, provided techniques for initial setup and pairing of IoT devices in April 2018. The document describes sample device pairing flows involving turning on a Fast Pair-enabled device, establishing a Bluetooth connection when the user taps to pair, and downloading a companion app. It also discusses Bluetooth secured pairing as a 3-phase procedure to establish keys for encrypted links and Bluetooth simple pairing models like numeric comparison, just works, out of band, and passkey entry. Wi-Fi protected setup methods like push button configuration, PIN entry, and out of band channels are also summarized. Finally, an overall architecture for handling device data on onboarding, organization, monitoring, and remote management is

1. Michael Mars, Cloud IoT Architect
michaelma@Softimize.co
Techniques for
Initial Setup and Pairing of
IoT Devices
April 2018

2. Your R&D Team
1. Turn on a Fast Pair-enabled device and
put it in pairing mode
o Android scans for BLE broadcasts in
close proximity of the user's phone
and discovers a Fast Pair packet
(if Bluetooth and Location are turned on)
o The packet is sent to server to
get back the device's product image,
product name and companion app
2. The user receives a notification asking
them to "Tap to pair" to the device.
The notification contains the product name and image
3. When the user taps on the notification, we use classic Bluetooth to establish a connection
4. A success notification is shown which contains a link to download the companion app
Let’s start with a pairing example
Source: https://android-developers.googleblog.com/2017/10/announcing-fast-pair-effortless.html

3. Your R&D Team
What are customers doing with IoT devices?

4. Your R&D Team
Overall architecture for handling device data

5. Your R&D Team
Sample Device Pairing Flow

6. Bluetooth Simple Pairing
 Bluetooth network consisting of one master and its slaves is called a piconet.
The master controls the timing of all Bluetooth communications on a piconet.
 The process of adding a new slave device to a Bluetooth piconet is called pairing.
 Bluetooth Simple Pairing is a set of security enhancements to the Bluetooth pairing mechanism.
The goal of Bluetooth Simple Pairing is to establish authentication credentials between the Bluetooth
master and slave devices.
Bluetooth Simple Pairing supports four different pairing models:
“Numeric Comparison” “Just Works” “Out of Band” and “Passkey Entry”
 Wireless communication is inherently vulnerable to message injection and eavesdropping attacks.
We cannot rely on the wireless channel alone for establishing credentials.
Thus, we rely on an additional out-of-band channel.
 We assume Dolev-Yao active attacker, who can eavesdrop, insert, modify, delay, and reorder
messages sent in the in-band channel.
Source: Kuo, Cynthia, Jesse Walker, and Adrian Perrig. "Low-cost manufacturing, usability, and security: an analysis of bluetooth simple pairing
and Wi-Fi protected setup." International Conference on Financial Cryptography and Data Security. Springer, Berlin, Heidelberg, 2007.

7. Your R&D Team
Bluetooth Secured Pairing
 Pairing is a three-phase procedure to establish keys to use for an encrypted link
 Pairing phase 1 allows 2 devices to exchange their input/output capabilities, which will decide what
security scheme can be used
 Phase 2 and 3 allows 2 devices to share keys that will be used at different stages of security features
 3 phases :
• Phase 1: Pairing request & response
• Phase 2: Pairing over SM protocol +
short-term encryption
• Phase 3: Keys exchange +
long-term encryption
 Bonding devices store encryption keys for
later secure communication

8. Bluetooth LE Pairing Process (cont.)

9. Bluetooth Simple Pairing
 Numeric Comparison
◦ When both master and slave can display a 6-digit number and
both provide “Yes” and “No” buttons
◦ Each device displays a 6-digit number computed from the pairing protocol
◦ 6 digits in the PIN (= 106 ≈ 220 possibilities),
an attacker can compromise the PIN with a probability of at least 2−20
 Just Works
◦ At least one of the devices has no display or “Yes/No” buttons (e.g. Bluetooth headset)
◦ Uses Numeric Comparison internally,
but does not display the six digits for comparison even if one of the devices has a suitable display
◦ No security against active attack
 “Out-of-band”
◦ When alternate communication medium exists on both devices, such as Near Field Communication (NFC)
◦ The alternate medium transfers a key between the devices and functions as the out of-band channel in the standard model.
◦ Transfer of a large key can provide more security
◦ Security depends on the user properly exercising the alternate communication channel
 Passkey Entry
◦ When one of the devices has a display and the other a keypad
◦ The device with the display randomly generates a 6-digit number, and the user enters this on the other device using the keypad
◦ The protocol splits the passkey into 20 bits and reveals one bit over 20 rounds of exchanges
◦ An eavesdropper can compute each bit of the passkey after it has been sent
(thus, a passkey can only be used securely once)
Pairing Algorithms

10. Wi-Fi Protected Setup
 Developed to address consumers’ credential configuration problem
 Wi-Fi Protected Setup supports three setup methods:
Push Button Configuration, PIN entry, and Out-of-band channel
 Wi-Fi, or IEEE 802.11, is a Local Area Network standard.
Usually deployed as an infrastructure network, which consists of one or more access points, and one or more mobile
devices called stations.
Each station forms a connection, called an association, with a single access point.
 Wi-Fi attempts to address more complex relationships among wireless devices:
The Wi-Fi scheme uses three different devices:
the registrar, which is the network enrollment center; an access point; and
an enrollee, which is the device being added to the network.
 For security Wi-Fi uses the 802.11i standard, also called WPA2.
WPA2 uses the IETF EAP protocol to mutually authenticate a station and the network and to derive a session key.
The session key provides confidentiality, integrity, and origin authenticity for each frame that a station and its access
point exchange.
Thus, Wi-Fi security relies on a long-lived authentication credential being established between the station and the
network.

11. Wi-Fi Protected Setup
 Push Button Configuration (PBC)
◦ The user pushes buttons on both the registrar and the enrollee devices.
The button push causes both to initiate an unauthenticated Diffie-Hellman exchange
◦ Has no security in the standard model
◦ The method assumes that the Diffie-Hellman peer is the correct device, i.e.,
that a malicious active attacker is not present.
◦ There is no out-of-band channel
 PIN
◦ The enrollee device has a four- or eight-digit PIN which is entered on the registrar’s keypad
◦ The PIN method uses the PIN as an authentication key to protect a Diffie-Hellman exchange
◦ The transfer of the PIN from the enrollee device to the registrar is the out-of-band channel for the PIN
method
◦ A random eight-digit PIN represents 108 = 226.65 possibilities. However, the PIN protocol splits the PIN
into two four-digit numbers. Each side commits to its value for each half of the PIN and exchanges
 “Out-of-band”
◦ An alternate communication channel, such as an NFC channel, transfers some information between the
registrar and the enrollee
◦ It is possible to obtain an arbitrary amount of security in the standard model,
provided the user actively participates in protecting the alternate channel from attack

12. Security Characteristics of Setup Models
Source: Kuo, Cynthia, Jesse Walker, and Adrian Perrig. "Low-cost manufacturing, usability, and security: an analysis of bluetooth simple pairing
and Wi-Fi protected setup." International Conference on Financial Cryptography and Data Security. Springer, Berlin, Heidelberg, 2007.

13. Pairing Process with NFC
The telephone contains a
BT device and an NFC reader
The headset contains a
BT device and an NFC Tag
The telephone will start reading the NFC Tag with NFC technology.
NDEF message on Tag will contain a Bluetooth carrier configuration data record:
• Bluetooth address = Headset Device address
• Generic access profile = Headset
• Local name = “Cool Headset”
1. The headset starts Bluetooth advertising with its own ‘Headset device Address’ after the NFC Tag
content is read
2. The telephone starts Bluetooth scanning for a device with ‘Headset device Address’ after it has read
the NFC tag
3. Bluetooth link is established by a simple intuitive user interaction
Pairing headset with telephone

14. Mobile application scans the QR-code found in the back of
the device to pair and connect the device to the user’s
smartphone
QR-Code Pairing

15.  Onboarding
◦ Control the provisioning workflow
◦ IoT Device Management Templates
◦ Certificates and access policies
 Organization
◦ Hierarchical model of your fleet
◦ Set policies on hierarchical basis
◦ Query the fleet on attributes (e.g. device type, firmware version)
 Monitoring
◦ Telemetry - real-time connection, authentication, and status metrics
 Remote Management
◦ Push new software and firmware
◦ Reset to factory defaults
◦ Reboot
◦ Bulk updates rollouts
Overall architecture for handling device data
Source: Jeff Barr, New- AWS IoT Device Management, in AWS IoT Device Management, AWS Re:Invent*, Internet Of Things*, 29 Nov 2017
https://aws.amazon.com/blogs/aws/aws-iot-device-management/

16. Your R&D Team
Recommended Resources
 Bluetooth Core Specification (version 4.0), and Supplements
 Bluetooth® Secure Simple Pairing Using NFC
 NFC Forum Connection Handover Technical Specification
 NFC Forum NFC Data Exchange Format (NDEF) Technical Specification
 Cynthia Kuo, Jesse Walker, and Adrian Perrig, Low-Cost Manufacturing, Usability, and Security: An
Analysis of Bluetooth Simple Pairing and Wi-Fi Protected Setup

17. Your R&D Team
Thank You!
Complicated Setup Process Frustrates the End-Users

18. Michael Mars
michaelma@softimize.co
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