1. ARSA: An Attack-Resilient Security Architecture for Multi-hop Wireless Mesh Networks Ki-Woong Park Computer Engineering Research Laboratory Korea Advanced Institute Science & Technology Oct 18, 2007 IEEE Journal on Selected Areas in Communications, 2006

2. COMPANY LOGO Prologue  Wireless Mesh Network at KAIST  Low deployment costs  Self-Configuration, Self-maintenance  Scalability, Robustness WiMesh Router In this paper,  Security Architecture Authentication, Key Agreement Attack-Resilient Security Protocol 2/20

3. COMPANY LOGO 1 2 3 4 Introduction to Wireless Mesh Network Problem to solve Authentication and Key Agreement Security Enhancement Contents 3/20 5 Discussion  Performance Evaluation

4. COMPANY LOGO Introduction to Wireless Mesh Network Access Points Mesh Routers Mesh Clients - Mobile & Short-lived ubiquitous services - DoS attacks - Security for multi-hop communication 4/20

5. COMPANY LOGO Problem to solve  Authentication and Key Agreement (AKA)  Router-Client AKA  Client-Client AKA  Attack-Resilient Security Architecture  Location Privacy Attack  Bogus-Beacon Flooding Attack  Denial-of-Access (DoA) Attack  Bandwidth-Exhaustion Attack Attacker Access Points Mesh Routers Mesh Clients 5/20

6. COMPANY LOGO Preliminaries  Cryptographic foundation of ARSA  Identity-Based Cryptography Eliminates the need for public-key distribution Publicly known identity information Public Key : Cyclic additive group of large prime order q : Cyclic multiplicative group of large prime order q 6/20

7. COMPANY LOGO System Model and Notation (1/3)  Credit-card-based business model  Kerberos, PKINIT Broker(i) Customer (j) WMN Router(j) Request for pass Universal Pass WMN Router (j) WMN Operator (i) 7/20

8. COMPANY LOGO System Model and Notation (2/3)  Domain Parameter & Certificate  Domain Parameter : publicly known  Domain Secret : keep confidential , : unique to each domain Access Points Mesh Routers P : Generator of : Domain Secret (Private Key) H 1 : hash function mapping to : Domain public Key domain-cert From TTP 8/20

9. COMPANY LOGO System Model and Notation (3/3) Access Points Mesh Routers (j) Mesh Clients Broker (i) WMN Operator (i)  Pass Model of ARSA  R-PASS (Router Pass) Issued by WMN Operator I Freshness is controlled by expiry -time  C-PASS (Client Pass) Provided by a Broker  T-PASS (Temporary Pass) Given by WMN Operator Mesh Clients (j) Public Key Private Key 9/20

10. COMPANY LOGO AKA (Authentication and Key Agreement) (1/4) Access Points Mesh Routers Access Points Mesh Routers WMN Operator “a” WMN Operator “b” Inter-domain AKA Intra-domain AKA Client-Client AKA 10/20

11. COMPANY LOGO  Inter-domain AKA Mesh Routers WMN Operator (i) A.1 A.2  Time check for t1 Expiry –time check  Validate domain-cert  Verify  To validate domain-cert From TTP hot list check of broker A.3 T-PASS AKA (Authentication and Key Agreement) (2/4) 11/20

12. COMPANY LOGO  Intra-domain AKA Mesh Routers B.1 B.2 Time check for t1 Expiry –time check Verify Derivation of Key PASS check Derivation of Key  To derive shared key AKA (Authentication and Key Agreement) (3/4) 12/20

13. COMPANY LOGO  Client-Client AKA C.1 C.2 PASS Check Derivation of Key Challenge PASS check Derivation of Key Response  To derive shared key : : AKA (Authentication and Key Agreement) (4/4) 13/20

14. COMPANY LOGO Security Enhancement (1/3)  Location Privacy Attack  Alias for client = =  Broker’s additional Key : Before : After :  armed with multiple alias (C-PASS, pass-key)  Bogus-Beacon Flooding Attack  Attack by flooding a mesh with a log of bogus beacons  Authenticity of beacons  Beacon Interval : ms  Super beacon interval : ms Hierarchical One-way hash-chain Technique 14/20

15. COMPANY LOGO  Bogus-Beacon Flooding Attack  Before Beacon (A.1)  After  Computationally infeasible to find a x+1 using a x  Pass check using,  Calculate  If( = ) then Use to proper beacon fields Security Enhancement (2/3) 15/20

16. COMPANY LOGO  Denial-of-Access (DoA) Attack  Bandwidth-Exhaustion Attack  CPU-bound puzzles  : random nonce created by Router  : puzzle indicator (Initial value = 0)  Client Generate nonce N Performing a brute-force search for a X – = # of Zero bits is zero Finding solution : Security Enhancement (3/3) 16/20

17. COMPANY LOGO Discussion  Identify a number of unique security requirements of the emerging multi-hop WMNs  ARSA : Attack-Resilient Security Architecture  More practical and lightweight  Mutual Authentication & Key Agreement  Attack-Resilient Technique Location Privacy Attack / Bogus-Beacon Flooding Attack Denial-of-Access (DoA) Attack / Bandwidth-Exhaustion Attack  Critique  No experiment / Simulation Result  Computationally Efficiency  Difference with Kerberos / PKINIT  Comparison with PKI 17/20

18. COMPANY LOGO 18/23 Symmetric KeyAsymmetric Key / IBC Key One Key - One Key to encrypt the data - One Key to decrypt the data Two keys - Public key to encrypt the data - Private key to decrypt the data ConfidentialityYes Digital Signature NoYes Non-repudiationNoYes Key DistributionNoYes Speed (ATmega) 3ms472ms Usage T-money (300ms), SpeedPass (100ms) [1] Internet Banking, E-Commerce  Symmetric Key vs. Asymmetric Key [1] F.Vieira, J.Bonnet, C.Lobo, R.Schmitz, and T.Wall “ Security Requirements for Ubiquitous Computing, ” EURESCOM. 2005 [2] A.Pirzada and C.McDonald, “ Kerberos Assisted Authentication in Mobile Ad-hoc Networks," in Proceedings of ACM International Conference Proceeding Series; Vol. 56, 2004. Discussion 18/20

19. COMPANY LOGO  Security Aspect  Computation Efficiency Additional Experiment Authentication Digital signature Non- repudiation Secure key distribution Kerberos YESNo PKIX YES M-PKINIT YES No YES ARSA YES No YES System MobileService Device Total Operation Time PuPrSPuPrS PKIX(RSA-1024bit)221200 34491035 ms Kerberos008006 8.122.4 ms M-PKINIT TGT117115 3305.1991.53 ms M-PKINIT SGT008004 8.082.42 ms ARSA Inter-domain AKA120111 3373.021011.9 ms ARSA Intra-domain AKA020110 1799539.7 ms ARSA Client-Client AKA021021 301.0290.31 ms 19/20

20. COMPANY LOGO Additional Experiment  Processing Times of cryptography operations PlatformCryptography Operation Time Complexity Service Device - CPU : PXA270 - RAM : SRAM 128 MB RSA 1024bit Private KeyAvg. 472ms1574.33 Public KeyAvg. 23ms75.33 AES 128bit EncryptionAvg. 0.3ms1.0 DecryptionAvg. 0.3ms1.0 Hash FunctionSHA-1Avg. 0.6ms2.0 Server - CPU : Xeon 3.2GHz - RAM: 4GB RSA 1024bit Private KeyAvg. 2.917ms9.72 Public KeyAvg. 0.170ms0.56 AES 128bit EncryptionAvg. 0.006ms0.02 DecryptionAvg. 0.006ms0.02 20/20

21. COMPANY LOGO