1. Performance and Efficiency in Wireless Security
Terry Fletcher, Senior Security Architect
Chrysalis-ITS

2. Overview m-Commerce needs for security Wireless networking constraints
Approaches
Need for efficiency
Opportunities for efficiency
Need for performance
Opportunities for performance
Future

3. M-Commerce Needs for Security
Intra-domain and end-to-end
Authentication
Data integrity
Data confidentiality
Wireless Networking Constraints
Handheld device size and processing power
Carrier network bandwidth
Carrier network reliability
Network discontinuities
Between different wireless carriers
Between wireless and wired networks

4. Approaches Carrier network security (e.g., GSM)
Transport level security (e.g., WTLS)
Application level security (e.g., S/MIME)

5. Opportunities for Efficiency
Need for Efficiency
Space limitations on devices
Processing limitations on devices
Carrier network bandwidth and reliability
Opportunities for Efficiency
Protocol optimization (WTLS vs. TLS)
Optimization of key exchange and cipher suite choices (ECDH optimized handshake, smaller MAC sizes for data integrity)
Minimizing certificate sizes (ECDSA signatures)
Minimizing key exchange/key agreement traffic (resume sessions)

6. Need for Performance At servers and gateways Typical SSL V3 numbers
E-Commerce apps – 5% – 40% of total traffic
On-line banking – 50+% of total traffic
Approx 0.5% - 1% of typical SSL traffic is handshake protocol
Handshake very compute intensive (beyond asymmetric crypto)
TLS Full handshake requires 44 hash operations on total of approx 75 k bits
Proportions likely higher for WTLS
WML records smaller than HTML web pages
Overhead with handshake significant compared to WML traffic volumes
Handshake still compute intensive even with optimization

7. Opportunities for Performance
Optimization
Asymmetric crypto acceleration (000’s of s/sec)
Offloading compute intensive portions of handshake protocol
Offloading symmetric crypto processing
RSA Sign 35ms Verify 3ms
ECDSA Sign 5.5 ms Verify 9 ms
EC acceleration – integer fields – choice of field primes can simplify math (Mersennes)
- GF(2) dedicated GF multiplier HW

8. Future Wireless networks evolving
Higher data rates & better reliability
Need for profiles for different network environments & operational requirements

9. Conclusion
Wireless security requires both efficiency and performance enhancement
Handshake protocol requires intensive computation beyond asymmetric crypto
Need to develop profiles to take greatest advantage of possible efficiency and performance enhancements

10. References WTLS 18 February 2000 TLS – RFC 2246“
TLS – RFC 2246 “