Security and Privacy in Wireless Sensor Networks INTRODUCTION Goals To achieve an algorithm that addresses the security issue of sensor networks including privacy confidentiality authentication and impersonation using public key cryptography and to study the effect of public key cryptography on sensor network specifically its effect on limited resources like power and memory Presented Overview of sensor network Security issues in sensor network and it challenges Proposed solution to address confidentiality and privacy Experimental results of cryptographic techniques using the EmStar Simulator Ongoing research in sensor network both general and security BACKGOUND Sensing subsystem Sensors connected to A D converter Battery subsystem Battery with DC DC conversions to provide require voltage Radio subsystem Deliver data or control messages to neighbors Processing subsystem Digitally process data for relay RAM ROM OS processor Network protocol data processing algorithm in ROM Location System and mobilizer May be mobile and location aware Overview of sensor node Data centric or node centric not address centric data aggregation Small cheap high density node network Convenient hard wired BS if any Ease of deployment Self organizing into ad hoc network Collaboration Fault tolerant and network robustness to loss of individual nodes Attribute based addressing and location aware Ideal for unreachable or inhospitable locations Deployment and maintenance impossible wire impractical Harsh environment extreme desert or harsh climate Unsafe environment toxic chemical or radiation facilities ocean depth or battlefields Unreachable environment moon planet Clustering Sensor Network Examples of sensor Node AMPS Adaptive multi domain power aware sensor project o The first prototype AMPS 0 was built with off the shelf components for rapid demonstrations Composed of an acoustic and seismic sensors StrongARM SA 1100 processor low power static and nonvolatile memory and a Bluetooth 2 4 GHz transceiver o The AMPS 1 a recent prototype uses only an acoustic sensor and an upgrade to StrongARM SA 1110 processor Transmit and receives 1Mbps at half duplex Berkeley Pico Radio project o Creates a low cost integrated radio with an energy dissipation of under 5nJ per communicated bit and an average power dissipation of 100 W Smart Dust project o Sacrifices some degree of functionality for small size Smart dust motes many tiny nodes easily the smallest micro sensor prototypes in development are targeted for ubiquitous applications General Research Health Monitor and assist patient Remembrance Agent Home GA Tech aware home Mitalda Environment Remote climate monitoring Military Battlefield surveillance reconnaissance Commercial Intra machine monitoring Monitor product quality Security Research The Energy Problem Sensors face the problem of battery power limitation Can t easily replace batteries in hostile environment Survive on little energy for months 5 10 years AA battery equivalent Sensors face the problem of memory CPU power and battery power limitation Energy Waste Computation CPU power collisions control packets overhead idle listening state radio component dominate power consumption of communication Energy scavenging operate node with energy derived from environment scheme proposed to eliminate battery use by converting ambient energy in environment to electrical energy Types include solar energy thermal gradients mechanical vibrations radiated RF The memory problem 4kb 512 RAM and ROM 128KB Flash and 4 512 flash memory 4KB RAM Security issues includes KEY ESTABLISHMENT AND TRUST cryptographic keys setup for later use key establishment techniques has to scale to large networks 100 1000 nodes CONFIDENTIALITY AND INTEGRITY protection against unwanted viewing and modification using cryptographic techniques of encryption and decryption AUTHENTICATION protection against eavesdropping injection and modification cryptography using authentication techniques PRIVACY deployment of secret surveillance networks for spying monitoring the movement location of a person or viewing their private data from sensor database or by eavesdropping ROBUSTNESS TO DENIAL OF SERVICE broadcasting a high energy signal to cause jamming violating MAC protocol by transmitting when not suppose to or by continuously requesting channel access with a request to send signal SECURE ROUTING routing for communication in sensor networks has to be secure RESILIENCE TO NODE CAPTURE AND NODE INJECTION sensor nodes may be deployed anywhere and unmonitored which exposes them to be captured or the injection of additional nodes into the network one defense is tamper resistant packaging ex self erasing if tamper with INTRUSION DETECTION the detection of anomalies in network in very expensive in terms of cost power and memory sensor network are meant to be cheap with low power and memory requirement new threat models must be understood and developed SECURE DATA AGGREGATION aggregate data to avoid false alarms and energy saving data aggregation locations may need to be secure Problem Cryptographic techniques for confidentiality and privacy has limited memory battery and CPU power Public key cryptography is expensive and infeasible due to its complexity slowness and high power consumption Therefore the use of symmetric keys has traditionally been used for authentication integrity and confidentiality Proposed solution scheme that uses less energy and memory simple public key cryptography key pre distribution key s is embedded inside the node before distribution elimination of the use of public parameters in public cryptograpy elimination of padding since each sensor sends a fixed amount of bits ex Sending temperature information requires only a 8 bits representation 0 200oC similar for position 0 360o use of small exponents similar to the Rabin scheme and small cipher block size two keys per sensor node except for aggregation node or cluster head relies on other characteristics time synchronization data aggregation and clustering Rationale time synchronization is important for determining the time of occurrence of events and chronological ordering of events data aggregation and security which is needed for both symmetric and asymmetric cryptography ex Authentication and has to be perform repeated security can take advantage of this and use this as an opportunity for authenticate acquire public private keys etc n 1 s p n 1 s n 1 s p p Agg CH Pu k n 1 s n 1 s