Secure Localization Algorithms for Wireless Sensor Networks proposed by A. Boukerche, H. Oliveira,...

Secure Localization Algorithms for Wireless

Sensor Networks

proposed by A. Boukerche, H. Oliveira, E. Nakamura, and A. Loureiro (2008)

Maria Berenice Carrasco

Outline

• Motivation (from two perspectives) • Secure Localization– Overview– Known attacks– Solutions

• Location Verification• Design considerations• Conclusions

Motivation

• Applications : Data fusion– Locations and timestamps

• Other communication protocols– Routing, location-based

authentication.etc.

• Why is Localization important?– Popularity of wireless sensor networks

(WSN)• Hostile environments• Monitoring & control applications

– Military fields, monitoring of structures, etc.

– The knowledge of sensor’s locations is required by

Motivation

• Why is Security important?– Vulnerability of WSN

• Remote environments• Broadcast nature of the channel

– What an attacker can potentially do?• Physical manipulation• Jamming• Injecting code

– As a result…• Wrong results: wrong decisions

GOAL: Make the node think it is somewhere different from actual location

Secure Localization

• Goal: To guarantee correctness despite of the presence of intruders

• Network model:• Beacons: GPS or manual configuration• Common nodes: requesting

• Classification:• Range-based localization: Distance• Range-free localization: No connectivity informationo Node-centrico Infrastructure-centric: BS, CA

Relative Localization

Secure Localization

• General Process has two phases:1. Information Collection: distance/angle

measure– # of hops, RSSI, ToA, AoARange-free ignores this phase

2. Location Computation: include reference points

Triangulation

Trilateration

Secure Localization

• Known Attacks– Consider an insider Vs. an

outsider

– Reply attack• Jams the transmission• Waits (extra delay)• Replays the same packet

pretending to be the sender• Inaccurate location estimation

Secure Localization

• Known Attacks– Range-change attack

• Special case of the Replay attack• Increase/decrease range measurements

– Impersonation• Victims: mostly beacon nodes

– Sybil attack• Claims multiple identities

Secure Localization

• Known Attacks– Wormhole attack

• Tunnel• Jams packets• Replays packets through this tunnel

Secure Localization

• Solutions– Cryptography

• Against impersonation and data corruption• Use of :

– Authentication » Verify the sender

– Data integrity» Data is unchanged» Example: distance bounding (based on

SEAD)

Secure Localization

• Solutions– Cryptography (continued)

• Symmetric cryptography– Common private key – WSN are resource-constrained

• Pre-deployed keys• Functions to derive keys: Storage Complexity• Compromised nodes defeat this mechanism

Secure Localization

• Solutions– Misbehavior Detection and Block

• Against compromised nodes• Observe behavior of nodes• Detect and revoke misbehaving nodes• Some techniques

– RTT observation between two neighbors» Assumption: extra delay of a replay attack

– Reputation-based mechanism» Beacon monitors its neighborhood -> table

Secure Localization

• Solutions– Robust Position Computation

• Filter erroneous information during computation• Assumption: Good nodes > Malicious nodes• Statistical techniques

– Least Squares Method

Location Verification

• BS also learn sensors’ locations – Data Aggregation

• Must verify the location claimed is correct– Did the event really happened there?

• An approach: The Echo Protocol– Check if the node is inside the claimed region– Two types of nodes: p (prover) and v (verifier)– Consider c (speed of light) and s (speed of

sound)

Location Verification

• An approach: The Echo Protocol (continued)– Intuition (Simple Case)

• v only verifies provers inside R

• If p is able to return the packet in sufficient time, then v is sure that p is within d(v,l) meters of v

• Otherwise: p is further away or processing delay

Design Considerations

• No system is totally safe– Network model & adversary model

• Level of security Vs. Available resources– Particular application– Range-based :

• Distance bounding: HW with nanosecond precision

– Asymmetric cryptography• More robust but energy consuming

Design Considerations

• Who initiates the secure localization process?– On-demand– Periodic process

• Useful domain for an intruder– Use only beacon nodes– Use beacon nodes and also nodes with

known positions as reference points

Conclusions

• It is not feasible to use tamper-resistant hardware– Low cost of sensor nodes– Massive deployment

• Trade-off required– Accuracy demanded by the application– Available resources– Environment

• Combination of techniques is desirable