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

• 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 • •

Applications : Data fusion

– Locations and timestamps

Other communication protocols

– Routing, location-based authentication.etc.

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

GOAL: location Make the node think it is somewhere different from actual As a result… •

Wrong results: wrong decisions

Secure Localization

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

Beacons: GPS or manual configuration Common nodes: requesting

Relative Localization Classification: •

Range-based localization: Distance

• o o

Range-free localization: No connectivity information Node-centric Infrastructure-centric: BS, CA

Secure Localization

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

# of hops, RSSI, ToA, AoA Range-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