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On Detecting Pollution Attacks in Inter-Session Network Coding. Anh Le, Athina Markopoulou University of California, Irvine. Linear Inter-Session Network Coding. S 1. S 2. x 1. x 1. x 1. x 2. x 2. x 2. Multiple sources Packets from different sources may be (linearly) coded together.
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On Detecting Pollution Attacksin Inter-Session Network Coding Anh Le, AthinaMarkopoulouUniversity of California, Irvine
Linear Inter-Session Network Coding S1 S2 x1 x1 x1 x2 x2 x2 • Multiple sources • Packets from different sources may be (linearly) coded together A x1+x2 B x1+x2 R2 R1 x2 x1 Anh Le, UC Irvine, Inter-Session Pollution Detection
Pollution Attacks in Inter-Session CodingMalicious Intermediate Nodes x2 x1 S1 S2 A x2 x1 y • Can be detected by existing intra-session approaches B R2 R1 x1 x2 y y Anh Le, UC Irvine, Inter-Session Pollution Detection
Homomorphic MAC-Based DetectionNo Pollution x1, t1 x2,t2 S1 S2 A x2,t2 x1, t1 x1+x2, t1+t2 B R2 R1 ü ü x1, t1 x2,t2 ü ü x1+x2, t1+t2 x1+x2, t1+t2 Anh Le, UC Irvine, Inter-Session Pollution Detection
Homomorphic MAC-Based DetectionAttack Case x1, t1 x2,t2 S1 S2 A x2,t2 x1, t1 x1+x’2, t B R2 R1 ü ü x1, t1 x2,t2 û û x1+x’2, t x1+x’2, t Anh Le, UC Irvine, Inter-Session Pollution Detection
Pollution Attacks in Inter-Session Coding x2 x1 S1 S2 Malicious sources • Inconsistent source packets • New and main challengein inter-session pollution • The main focus of the paper A x'2 x1 x1+x2 B R2 R1 x'2 x1 x1+x2 x1+x2 Anh Le, UC Irvine, Inter-Session Pollution Detection
Intra-Session MAC-Based Detection Failed for Malicious Sources S1 S2 x1, t1 x2, t2 A x'2, t’2 x1+x2, t1+t2 B R2 R1 ü x’2, t’2 ü x1+x2, t1+t2 Anh Le, UC Irvine, Inter-Session Pollution Detection
Prior Work on Inter-Session Pollution Defense • Homomorphic signature for Detection[Agrawal, PKC ’10] • Expensive computation • Large signature • Signature-based Identification[Dong, WiNC ‘09] Anh Le, UC Irvine, Inter-Session Pollution Detection
Outline • Background and Motivation • Inter-Session Pollution Attacks • Main Challenges • Prior Work • InterMac Detection (more in the paper: Hash and SpaceMac based Detection) • Evaluation • Conclusion Anh Le, UC Irvine, Inter-Session Pollution Detection
InterMac: Threat Model S - 1 sourcesmay be malicious Intermediate nodes may be malicious Receivers are trusted Anh Le, UC Irvine, Inter-Session Pollution Detection
Main Challenge and Key Observation x1 S1 S2 x2 A Sources must generate tags using different keys B R2 R1 Main Challenge: Malicious sources Anh Le, UC Irvine, Inter-Session Pollution Detection
Overview of InterMac • Homomorphic (MAC) for inter-session network coding • Each source generate MAC tags using different keys • The tags are still combinable without knowing the key Anh Le, UC Irvine, Inter-Session Pollution Detection
InterMac DetectionMain technique k1 k2 Inner Product Homomorphic MAC [Le, NetCod ’10] [Li, INFOCOM ’10] S1 S2 x1, t1=x1·k1 x2, t2=x2·k2 A x1+x2, t1+t2 B Verify: (x1 + x2) (k1 + k2) = t1 + t2 x1k1 + x2k2 + x1k2 + x2k1= t1+ t2 R2 R1 k1, k2 k1, k2 ü x1+x2, t1+t2 Main technique: Orthogonality of ki and xj Anh Le, UC Irvine, Inter-Session Pollution Detection
InterMac Construction Using a Trusted Controller: ki· xj= 0 • Inner Product Homomorphic MAC • [Le, NetCod ’10] • [Li, INFOCOM ’10] Multiple Keys Anh Le, UC Irvine, Inter-Session Pollution Detection
InterMac: Security Game x2,t2 x1, t1 S1 S2 Challenger A (idi, Vi) Vi:committed source space Tags of basis vectors of Vi S-1 keys of Vi B R2 R1 Adversary • Adversary wins if: • id* = idjfor some j • y* • t* is a valid tag of y* (id*, y*, t*) Anh Le, UC Irvine, Inter-Session Pollution Detection
Security of InterMac Anh Le - UCI - NC Pollution Defense
Basic Key Generation in InterMac (x1 | p1) ·k2 = 0 k1, k2 (x2 | p2) ·k1= 0 C commit x2 commitx1 k2, p2 k1, p1 x1 S1 S2 x2 Send (x2 | p2) Send (x1 | p1) Key Property: Orthogonality of ki and (xj | pj) Anh Le, UC Irvine, Inter-Session Pollution Detection
Efficient Key Generation in InterMac (x1·ḵ2) +p1k’2 = 0 k1= (ḵ1 | k’1) k2= (ḵ2| k’2) (x2·ḵ1) +p2k’1 = 0 C commit Enc(x1·ḵ2) commit Enc(x2·ḵ1) k2, p2 k1, p1 Enc(ḵ1) Enc(ḵ2) x1 S1 S2 x2 Bandwidth Efficiency: Sending Enc. of a single symbol instead of a full vector Anh Le, UC Irvine, Inter-Session Pollution Detection
InterMac Detection Illustration k1, k2 k1, k2 now what S2sends must be orthogonal to k1 k1, p1 k2, p2 C Gen Gen S1 S2 x1 x2 p1, t1 p'2,t’2 p1, t1 p2,t2 A p1+p’2, t1+t’2 (p1+p’2) dropped because p’2 notorthogonal to k1! (p1k1+p’2k2+p’2k1) ≠ t1+t’2 B p1+p’2, t1+t’2 R2 R1 Anh Le, UC Irvine, Inter-Session Pollution Detection
Outline • Background and Motivation • Inter-Session Pollution Attacks • Main Challenges • Prior Work • InterMac Detection • Evaluation • Conclusion Anh Le, UC Irvine, Inter-Session Pollution Detection
InterMac Performance Evaluation Bandwidth Overhead [27] Agrawal et al. [PKC ‘10] [20] Zhang et al. [INFOCOM ‘11] Anh Le, UC Irvine, Inter-Session Pollution Detection
InterMac Performance Evaluation Computation Overhead [27] Agrawal et al. [PKC ‘10] [20] Zhang et al. [INFOCOM ‘11] Anh Le, UC Irvine, Inter-Session Pollution Detection
Conclusion • Inter-session: Malicious sources • InterMac: First multi-key MAC scheme for inter-session • Each source signs using its own key • Still homomorphic • In-network detection based on InterMac • 100 times faster than [PKC ‘10] • 5 times less bandwidth than [PKC ’10] • Require a trusted controller ( [PKC ’10] does not ) • More in the paper: Hash and SpaceMac-based detection Anh Le, UC Irvine, Inter-Session Pollution Detection
Links: • Network Coding Security:http://www.ics.uci.edu/~anhml/projects.html#nc-security • UC Irvine Networking Group – Network Coding Project:http://odysseas.calit2.uci.edu/doku.php/public:network-coding Anh Le, UC Irvine, Inter-Session Pollution Detection