This document discusses using a hierarchical certificate authority with elliptic curve cryptography to improve security in ZigBee networks. It begins with an overview of the Internet of Things and wireless sensor networks. It then discusses ZigBee protocols and vulnerabilities in key distribution and management. The document proposes a solution using a hierarchical certificate authority to calculate, store, and distribute certificates with elliptic curve cryptography to nodes in the network. This is intended to provide a more secure, reliable, and scalable approach for authentication in 802.15.4 networks.

1. INTERNET OF THINGS
SECURITY
ZigBee Networks 802.15.4 Protocol
Hierarchical Certificate Authority w/ ECC
Abe Arredondo
Luis Stolk

2. Agenda & Overview
Internet of Things (IoT)
Wireless Sensor Networks (WSN)
IoT Protocols and ZigBee
Medical Application Network Model
ZigBee
Vulnerability Problems
Alternative from Razouka [3]
Our Innovative Idea
Hierarchical Certificate Authority w/ ECC

3. Internet of Things
• Integration of wireless sensors, networks, protocols
technologies, ID’s, objects, etc.
• Gartner estimates that by 2020 there will be 30 Billion
devices connected to the IoT [5]

4. WSN: What is it?
Infrastructure-less Ad Hoc
autonomous node network to
monitor environmental
conditions.
Inexpensive, low power,
does not have much
processing or storage
capabilities
IEEE: 802.15.4, Different Radio, Not TCP-IP [7]
Achilles heel is that WSN are battery powered
Myria-Node device
WSN system are distributed decentralized architectures. Usually has
a local Base Station (BS) with processing capabilities to make
decisions on sensed physical environmental measurements

5. Internet of Things & ZigBee
❖Existing Wi-Fi uses 802.11 and the IoT uses 802.15.4
❖Early adopters of the IoT use an 802.15.4 protocol called
ZigBee (initial 2004, Trust Center 2007 & Security)
➢Short range 10 to 100 meters
➢Line of sight (Mesh Networks)
➢Low rate data transfers
❖ZigBee security is based on 128 bit Advanced Encryption
Standard (AES) Counter Cipher Block Chaining Message
Authentication Code (CCM) AES-128-CCM
➢Provides support for public key infrastructure
■X.509 v3 certificates
■256 Elliptic Curve Cryptography cipher suite

6. Body Area Network
Medical App
Young Sil Lee [1]

7. Network Model: Medical
Application

8. Design Goal
Our goal is to design a
Confidential, Reliable /
Available Fast, and Scalable
802.15.4 network possible
Based On:
• Hierarchical Certificate
Authority (CA) wireless
gateways
• Elliptic Curve
Cryptographic (ECC)
algorithm

9. Zigbee Vulnerability Problem
1) Key Distribution: Over the air or Pre-Installed
a) ZigBee High Security: All nodes = E(Master Key)
b) Key Establishment:
i) Symmetric Key Establishment
ii) Certificate-based Key Establishment (X.509)
iii) Alpha-secure Key Establishment
c) ZigBee Standard Security: unencrypted Key over the air
d) Pre-Installed Keys: Manually with Commissioning Tool
1) Frame Counter using ordered sequence of inputs
1) Forward Security: Master and Link Keys are never
revoked from sensor exiting a network (like WEP!)

10. ZigBee Vulnerability Page 2
4) Eavesdropping & Data Manipulation: traffic
sniffing, data injection, packet decoding
a) Pre-install methods require re- flashing device to ch key
b) 802.15.4 has no replay protection, ZigBee small imp
c) KillerBee Software & Hardware
http://www.willhackforsushi.com
i) AVR RZ Raven USB Stick (RZUSB, $40)
ii) sniff + inject
iii) AT90USB1287 uC w/ AT86RF230 802.15.4 transc
iv) 4 LED's, PCB antenna

11. Protocols - Trusted Center (~KDC)
Notation: IDA || NA || H [ NA || KRA ]
Pseudo Random # nonce to prevent replay attack
Razouka [3]
~ Key Distribution Center
DB: IDi Node ID
KRi Node Private K
Ks Session Key
IDA
KRA
IDB
KRB

12. Hierarchical X.509 CA w/ ECC
Venue Domain Wireless IoT Gateway
Calculate, Store, & Distribute
IoT Directory: IDi Node ID
KRi Node Private K
Ci Signed Certificate
The ZigBee method: X.509 Certificate-based Key Establishment (CBKE) using the ECC algorithm
IDA
KUAuth
ECC

13. Review Q&A
Internet of Things (IoT)
Wireless Sensor Networks (WSN)
IoT Protocols and ZigBee
Medical Application Network Model
ZigBee
Vulnerability Problems
Alternative from Razouka [3]
Our Innovative Idea
Hierarchical Certificate Authority w/ ECC

14. References
1. An Efficient Encryption Scheme using Elliptic Curve Cryptography (ECC) with Symmetric
Algorithm for Healthcare System. Young Sil Lee, Esko Alasaarela and Hoon Jae Lee.
Department of Ubiquitous IT, Dongseo University Graduate School, Department of Electronic
Engineering, University of Oulu 47 Jurye-ro, Sasang-gu, Busan, Rep. of Korea FI-90014, Oulu,
Finland.
2. A standard compliant security framework for IEEE 802.15.4 networks.G. Piro, G. Boggia, and L.
A. Grieco Department of Electrical and Information Engineering (DEI) Email: {g.piro, g.boggia,
a.grieco}@poliba.it Politecnico di Bari, Italy
3. New security approach for ZigBee Weaknesses. Wissam Razouka, Garth V. Crosbyb,
Abderrahim Sekkakia. Hassan II University, Faculty of science, Dept of mathematics and
computer science, 5366, Casablanca, Morocco Southern Illinois University, Dept of technology,
Engineering building, 62901, Illinois, USA
4. Zigbee Gateway Patrick Kinney (pat.kinney@ieee.org)
https://www.zigbee.org/zigbee/en/events/documents/SensorsExpo/7-Sensors-Expo-kinney.pdf

15. Appendix

16. Service Scenario
1. A collection of ZigBee devices sends data to a remote service over
IP. 802.15.4
2. A ZigBee security device is preconfigured to connect to a web
service through a gateway (Enter WSN, Exit WSN: Key Revocation)

17. IP Command Translation [1]
When working through a ZigBee
Gateway, an IP device sends a
command:
• “Turn on the light in the northeast
corner of Room 123”
✓Gateway translates this command
to a packet that is compatible with
the appropriate ZigBee lighting
profile
✓Gateway also translates the logical
address into a network address,
and transmits the packet on behalf
of the originator
✓Gateway acts as an agent on behalf
of the IP device, isolating the IP
device from the details of ZigBee
operation and vice versa

18. ZigBee
Gateway
A ZigBee Gateway is
intended to provide an
interface between
ZigBee and IP devices
through an abstracted
interface on the IP side.
The IP device is isolated
from the ZigBee protocol
by that interface. The
ZigBee Gateway
translates both
addresses and
commands between
ZigBee and IP. [1]

19. Gateway Stack Diagram
The IP stack is terminated at the Gateway as is the ZigBee Stack. The Gateway provides translation between
the respective stack [1]
A ZigBee ZED extends the ZigBee network over an IP based network. Since the specific PHY and MAC layers are not
pertinent as long as the network layer is IP based, the ZED will work over Ethernet or Wi-Fi types of devices.