On Detecting Pollution Attacks in Inter-Session Network Coding Anh Le, Athina Markopoulou University of California, Irvine

On Detecting Pollution Attacksin Inter-Session Network Coding

Anh Le, Athina MarkopoulouUniversity of California, Irvine

Linear Inter-Session Network Coding

Anh Le, UC Irvine, Inter-Session Pollution Detection 2

S1 S2

R2 R1

A

B

x1+x2

x2

x1 x2x1 x2x1 x2

x1+x2

x1

• Multiple sources

• Packets from different sources may be (linearly) coded together

Pollution Attacks in Inter-Session Coding

Malicious Intermediate Nodes

3

S1 S2

R2 R1

A

B

x2

x1 x2

y y

x1

x1

x2

• Can be detected by existing intra-session approaches

y

Anh Le, UC Irvine, Inter-Session Pollution Detection

Homomorphic MAC-Based DetectionNo Pollution

4

S1 S2

R2 R1

A

B

x1, t1 x2,t2

x2,t2x1, t1

x2,t2x1, t1

x1+x2, t1+t2

x1+x2, t1+t2 x1+x2, t1+t2

ü üü ü


Homomorphic MAC-Based DetectionAttack Case

5

S1 S2

R2 R1

A

B

x1, t1 x2,t2

x2,t2x1, t1

x2,t2x1, t1

x1+x’2, t

x1+x’2, t x1+x’2, t

ü üûû


Pollution Attacks in Inter-Session Coding

6

S1 S2

R2 R1

A

B

x'2

x'2

x1

x1

x2

Malicious sources

• Inconsistent source packets

• New and main challenge in inter-session pollution

• The main focus of the paper

x1

x1+x2

x1+x2 x1+x2


Intra-Session MAC-Based Detection Failed for Malicious Sources

7

S1 S2

R2 R1

A

B

x1, t1 x2, t2


x'2, t’2

x’2, t’2 ü

x1+x2, t1+t2

x1+x2, t1+t2 ü

Prior Work on Inter-Session Pollution Defense

8

• Homomorphic signature for Detection [Agrawal, PKC ’10]

• Expensive computation• Large signature

• Signature-based Identification[Dong, WiNC ‘09]


1. Background and Motivationo Inter-Session Pollution Attackso Main Challenges

2. Prior Work

3. InterMac Detection (more in the paper: Hash and SpaceMac based Detection)

4. Evaluation

5. Conclusion

Outline

9Anh Le, UC Irvine, Inter-Session Pollution Detection

InterMac: Threat Model

10

• S - 1 sourcesmay be malicious

• Intermediate nodes may be malicious

• Receivers are trusted


Main Challenge and Key Observation

11

• Main Challenge: Malicious sources

Sources must generate tags using different keys

S1 S2

R2 R1

A

B

x1 x2


Overview of InterMac

12

• Homomorphic (MAC) for inter-session network coding

– Each source generate MAC tags using different keys

– The tags are still combinable without knowing the key


13

InterMac DetectionMain technique


x2, t2=x2·k2S1 S2

R2 R1

A

B

k1

k1, k2

x1, t1=x1·k1

k2

k1, k2

x1+x2, t1+t2

x1+x2, t1+t2

Verify:(x1 + x2) (k1 + k2) = t1 + t2

x1k1 + x2k2 + x1k2 + x2k1 = t1+ t2

Inner Product Homomorphic MAC[Le, NetCod ’10][Li, INFOCOM ’10]

Main technique: Orthogonality of ki and xj

ü

InterMac Construction


Inner Product Homomorphic MAC• [Le, NetCod ’10]• [Li, INFOCOM ’10]

Multiple Keys

Using a Trusted Controller:

ki · xj = 0

InterMac: Security Game

15

o Adversary wins if:• id* = idj for some j

• y* • t* is a valid tag of y*


S1 S2

R2 R1

A

B

x1, t1 x2,t2

(idi, Vi)

Vi :

committed source space

(id*, y*, t*)

Tags of basis vectors of Vi

S-1 keys of Vi

Adversary

Challenger

Security of InterMac

Anh Le - UCI - NC Pollution Defense 16

Basic Key Generation in InterMac

17

k1, k2

x1 x2

commit

x1

commit

x2

C

k1, p1 k2, p2

(x1 | p1) · k2 = 0

(x2 | p2) · k1 = 0

S1 S2

Send (x1 | p1) Send (x2 | p2)


Key Property: Orthogonality of ki and (xj | pj)

Efficient Key Generation in InterMac

18

k1= (ḵ1 | k’1) k2= (ḵ2 | k’2)

x1 x2

commit

Enc(x1·ḵ2)commit

Enc(x2·ḵ1)

k1, p1 k2, p2

(x1·ḵ2) + p1 k’2 = 0

Enc(ḵ2) Enc(ḵ1)

C

S1 S2

(x2·ḵ1) + p2 k’1 = 0

Bandwidth Efficiency: Sending Enc. of a single symbol instead of a full vector


x2

k1, k2

19

S1 S2

R2 R1

A

B

InterMac Detection Illustration

CGen Gen

k1, p1 k2, p2

p1, t1p1, t1

p1+p’2, t1+t’2

p1+p’2, t1+t’2

p'2, t’2

(p1+p’2) dropped because p’2 not orthogonal to k1!

(p1k1+p’2k2+p’2k1) ≠ t1+t’2

p2, t2

now what S2 sends must be orthogonal to k1


x1

k1, k2

1. Background and Motivationo Inter-Session Pollution Attackso Main Challenges

2. Prior Work

3. InterMac Detection

4. Evaluation

5. Conclusion

Outline


21

InterMac Performance Evaluation

Bandwidth Overhead

[27] Agrawal et al. [PKC ‘10] [20] Zhang et al. [INFOCOM ‘11]


22

InterMac Performance Evaluation

Computation Overhead

[27] Agrawal et al. [PKC ‘10] [20] Zhang et al. [INFOCOM ‘11]


o Inter-session: Malicious sources

o InterMac: First multi-key MAC scheme for inter-session• Each source signs using its own key• Still homomorphic

o 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 )

o More in the paper: Hash and SpaceMac-based detection

Conclusion


24

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


http://www.ics.uci.edu/~anhml/projects.html



http://odysseas.calit2.uci.edu/doku.php/public:network-coding

Documents

On Detecting Pollution Attacks in Inter-Session Network Coding Anh Le, Athina Markopoulou University of California, Irvine