This document summarizes a master's thesis on security protocols for sensor networks. It introduces SPINS, which defines requirements for data confidentiality, authentication, integrity, and freshness. It describes the SNEP, counter-exchanging, and μTESLA protocols. SNEP provides semantic security, authentication, and replay protection with low overhead. Counter-exchanging handles bootstrapping and re-synchronizing counters with nonces. μTESLA allows for authenticated broadcast from a base station to sensor nodes in an efficient way by disclosing authentication keys. The thesis evaluates the implementation and performance of these protocols.

1. SPINS: Security Protocols
for Sensor Networks
Master’s Degree 29th
Park. Joon-young

2. Contents
• Introduction
• System Assumptions
• Requirements for Sensor Network Security
• SNEP / Counter Exchanging / µTESLA
• Implementation
• Evaluation
• Question & Answer

3. Introduction
Limited Processing Power
Limited Storage
Low Bandwidth
Inefficient Energy
Sensors will have..

4. SPINS
Data Confidentiality
!
Two-party Data Authentication
!
Integrity
!
Evidence of Data Freshness
Authenticated Broadcast
for Resource-constrained
Environments
SNEP µTESLA

5. System Assumptions

6. BaseStation
Communication arch.
Node
e.g., sensor readings
Base Station

7. NodeBaseStation
Communication arch.
e.g., specific requests
Node

8. NodeBaseStation NodeNode
Communication arch.
e.g., routing beacons, queries, reprogramming..
Node
Node
Node

9. Other assumptions
Communication arch.
Trust requirements Design guidelines

10. Requirements
WEAK?
!
STRONG?
Data Confidentiality
Data Authentication
Data Integrity

11. SNEP(with weak freshness)
Semantic security
Data authentication
Replay protection
Low communication overhead
FreshnessFreshness

12. SNEP(with strong freshness)
Freshness
send nonce

13. Counter exchanging
Bootstrapping Counter
Re-synchronizing Counter
nonce

14. TESLA
Efficient
Authenticated Broadcast Protocol

15. TESLA
NOT APPLICABLE
uses Digital Signature
uses Big Packet Size

16. TESLA
uses Symmetric mechanisms
discloses the key 1/epch

17. µTESLA
Base Station
- Sender Setup
…, , , ,
one-way func.
…

18. µTESLA
Base Station
- Broadcasting Auth.
…, , ,
Nodes

19. µTESLA
Base Station
- Broadcasting Auth.
…, , ,
Nodes

20. µTESLA
Base Station
…, , ,
Nodes
- Bootstrapping
New Receiver
Hi

21. µTESLA
Base Station
…, , ,
Nodes
- Authenticating
broadcast packets

22. µTESLA
Fake Station Nodes
- Authenticating
broadcast packets

23. Implementation
• subset of RC5
• CTR Encryption Function
• used Nonce
• use MAC for PRG
• compute MAC per packet

24. Evaluation
Code Size
Performance

25. Evaluation
Ram requirements
Energy costs