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Public Key Authentication in Wireless Sensor Network (2). Jeonil Kang (dreamx@seclab.inha.ac.kr). Public Key Cryptography. Key agreement problem in wireless sensor network “How to set up secret keys between communicating nodes.” Symmetric key techniques
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Public Key Authentication in Wireless Sensor Network (2) Jeonil Kang(dreamx@seclab.inha.ac.kr)
Public Key Cryptography • Key agreement problem in wireless sensor network • “How to set up secret keys between communicating nodes.” • Symmetric key techniques • The secret keys are pre-distributed among sensors before their deployment. • Due to the limitation on memory, symmetric key techniques are not able to achieve both a perfect connectivity and a perfect resilience for large-scale sensor networks. • Public key cryptography • eliminate the connectivity and resilience problems. • Common criticism: computational complexity and communication overhead. • ECC signature verification: 1.62s (160-bit Atmega 128) PKC becomes widely accepted for WSNs.
Public Key Authentication Non-certificate B B<CA> CA D C<CA> B<CA> B D<E> D<E> B<A> E B<A> A C<CA> C A C PKCA PKA PKE Certificate
Public Key Authentication with Hash • Naïve Scheme: Trusted hash value • instead of trusted public key • This method still has the memory-usage problem. • Memory-Efficient Scheme: Merkle Tree Root Hash Φ(V)=hash(Φ(Vleft)||Φ(Vright)) Φ(Li)=hash(id,pki)
Merkle Tree Root Hash A’s proof H= A idA, pkA, A’s proof Communication Overhead = L × H B Root Hash
2D Grid Based Scheme C S D Proof served by S B S’ A S B A Proof served by C C S D Worst Case
Intersection Node & Loop Model • When a intersection node was compromised, C S B C S B No Way!
Memory / Communication Trade-off 2D Grid Based Scheme (2 Root Hash) This is 1.5D GBS! Basic Scheme (2 Root Hash) = 1D GBS Du Scheme (2 Root Hash)
3D GBS on 2D C S D 3D Grid Based Scheme (3 Root Hash) B S’ A
3D GBS on 3D 3D Grid Based Scheme (3 Root Hash) C S S’ B
3D GBS on 3D S1 1 3D Grid Based Scheme (3 Root Hash) C 2 3 S2 B
M-D GBS M-1 intersection nodes Is This Possible on 2D or 3D?