1. Towards an optimized BlockChain for IoT
Ali Dorri*#, Salil Kanhere*#, Raja Jurdak#*
*University of New South Wales
#CSIRO Data61

2. IoT security and privacy is challenging
DDOS attack on DNS
IoT security and privacy is challenging
DDOS attack in the US in 2016.
Simple IoT devices were compromised and used to launch a large DDOS attack by flooding DNS service provider called Dyn
coming from "tens of millions of IP addresses at the same time.
2 hours downtime
Source: Downdetector.com.
Optimised BlockChain for IoT | Raja Jurdak

3. Possible Solution
Optimised BlockChain for IoT | Raja Jurdak

4. BlockChain Overview A distributed immutable time-stamped ledger
Creates a secure network over untrusted users
Changeable PKs as users identity introduce high level privacy
Demands for solving a puzzle to append blocks to the BlockChain (mining)
Optimised BlockChain for IoT | Raja Jurdak

5. BlockChain challenges in IoT
Resource Consuming
Resource-constrained devices
Block mining is time consuming
Demands low latency
Scales poorly with network size
Very large scale
Bandwidth-inefficient
Limited bandwidth and energy resource
Poor scaling due to fully distributed nature
Optimised BlockChain for IoT | Raja Jurdak 4

6. Optimising the BlockChain for IoT
Hierarchical structure
Private centralized BlockChain at local level
Public distributed BlockChain at overlay
Clustered overlay topology - limited nodes process BlockChain
Optimised BlockChain for IoT | Raja Jurdak

7. IoT BlockChain Features
Separate data and transactions flow - decreased delay
Distributed trust between CHs – reduced processing
Optimised BlockChain for IoT | Raja Jurdak

8. Local Immutable Ledger
Smart Home
Local Immutable Ledger
LBM
Smart home devices are managed centrally by the home manager
Devices can share data with each other or the cloud storage when they receive permission from the owner
LBM manages a local immutable ledger that has transactions and policy header.
Policy is used by the home owner to enable user to have control over the smart home communications
Uses DHsymmetric encryption for efficiency
Optimised BlockChain for IoT | Raja Jurdak

9. Transactions handling
CHs
Request data
Forwarding
Authorization
Transaction to be stored
Request data
Request device data
Request data
Request data
note separation of data and transaction flow
CHs exchange blocks and cross-verify blocks from others
Establish consistency and distributed trust to reduce proportion of verified blocks from trusted sources
Optimised BlockChain for IoT | Raja Jurdak

10. Comparison with Bitcoin Blockchain
Feature
Bitcoin BlockChain
Immutable Ledger
Public BlockChain
Mining requirement
POW
None
Forking
Not allowed
Allowed
Double spending
Not acceptable
Not applicable
Encryption
Asymmetric
Symmetric
BlockChain visibility
Public
Private
Transaction dissemination
Broadcast
Unicast
Unicast/Multicast
Distributed verification
All
Some
Optimised BlockChain for IoT | Raja Jurdak

11. Performance evaluation – Processing
Simulations using NS3 to study the trust method - 50 nodes of which 13 are CHs
Optimised BlockChain for IoT | Raja Jurdak

12. Evaluation - Accessibility threats
DDOS attack
Devices are not directly accessible
Home manager controls all incoming and outgoing transactions
Keylists on CHs
Target threshold of received transactions
Optimised BlockChain for IoT | Raja Jurdak

13. Accessibility threats
Dropping attack
Optimised BlockChain for IoT | Raja Jurdak

14. Accessibility threats
Dropping attack
Elect new cluster head
Optimised BlockChain for IoT | Raja Jurdak

15. Accessibility threats
Dropping attack
Appending attack
Elect new cluster head
False block
False block
Inject fake transactions in a block
Optimised BlockChain for IoT | Raja Jurdak

16. Accessibility threats
Dropping attack
Appending attack
Elect new cluster head
Detected by other CHs
False block
False block
Detected by other cluster heads
Graceful degradation with proportion of compromised CHs
Optimised BlockChain for IoT | Raja Jurdak

17. Summary Optimised blockchain for IoT Main features Future directions
Maintains security/privacy benefits of classic BC
Significantly reduces classic BC overhead
Main features
Two blockchain tiers
Separate data and transaction flow
Remove proof-of-work
Introduce distributed trust
Future directions
More extensive performance evaluations
Mobile scenarios
Optimised BlockChain for IoT | Raja Jurdak

18. Thank you
Raja Jurdak, PhD Senior Principal Research Scientist & Research Group Leader, Distributed Sensing Systems
Cyberphysical Systems Program t e w