The document discusses wireless sensor networks and describes a project using MICAz motes. It covers: 1. The characteristics and applications of wireless sensor networks, including sensing data and forwarding it through multi-hop routing. 2. Security threats in sensor networks like eavesdropping and denial of service attacks, and solutions like frequency hopping and encryption. 3. The project uses MICAz motes running TinyOS to sense temperature data and forward it securely through the network to a base station. Skipjack encryption and Diffie-Hellman key exchange provide security.

1. Data Sensing & Secured Data Forwarding in multi-hop Wireless Sensor Network using MICAz based motes Presented by JayantPathak (2006ECS22) Kumar Vikramjeet (2006ECS50) Under the Supervision of Mrs. Sonika Gupta

2. Introduction to WSN A wireless sensor network (WSN) is a wireless network consisting of spatially distributed autonomous devices using sensors to cooperatively monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, motion or pollutants at different locations. Characteristics of WSN Very Limited Resources Unreliable Communication Unattended Operation

3. Wireless Sensor Networks Sensor nodes sense the data & send it upward in the network hierarchy Base Station logs the collective data. Sensor nodes/motes may act as router & perform data aggregation

4. APPLICATIONS Of WIRELESS SENSOR NETWORKS

5. Benefits of Multi-hop network Access Point based Network Multi-hop network AP-based topology with maximum coverage and throughput environment is challenging. Range & data transfer is affected by - node location - type of house Multi-hop topology - design of future home wireless networks and requirements for future wifi-enabled consumer electronic devices Advantages - wide coverage attained by nodes location - implementation of mesh

6. Security threats in Sensor Networks Adversaries can easily sniff on, intercept, inject and alter transmitted data. Adversaries can Interact with networks from a distance by inexpensive radio transceivers and powerful workstations. Resource consumption attacks - Adversaries can repeatedly send packets to drain nodes battery and waste network bandwidth, can steal nodes.

7. Example of Intruder Attacks Type 1 Type 2 Battery consumed Bandwidth loss Data packet Data packet A B Attacked(packet spoofed) IN False packet False packet False packet

8. Solutions of threat A specific frequency channel is allocated to WSN at a time which is designated by RF_Channel Group_id should be altered manually RF_Channel altered manually after regular interval Each pair of motes share different symmetric keys. All communication are encrypted symmetric keys between motes.

10. Each side then generates a public key (letter B), which is a derivative of the private key.

11. The two systems then exchange their public keys. Each side of the communication now has their own private key and the other systems public key (letter C).

14. processes data and controls the functionality of other components in the sensor node.

15. The functionality of both transmitter and receiver are combined into a single device know as transceivers

16. Sensors sense or measure physical data of the area to be monitored.

17. The continual analog signal sensed by the sensors is digitized by an Analog-to-digital converter and sent to controllers for further processing.

18. Power consumption in the sensor node is for the Sensing, Communication and Data Processing.

19. kinds of memory are on-chip memory of a microcontroller and Flash memory

20. Micro-controller:ATMEGA 128

21. Transceiver: TI CC2420 802.15.4/ZigBee compliant radio 2.4-2.48 GHz (250 kbps data rate)

22. External Memory: 128K Flash

23. Program + Data Memory: 4K RAM

24. Programming : nesC

25. Platforms: TinyOS, SOS, MantisOS and Nano-RK Support

26. 2.6-3.3 V power supplyIn Context of MICAz motes

27. Appropriate encryption for WSN Encryption security depends on Key size & No. of rounds Key length is limited by the limited processing power of motes Keysize Processing energy Battery life Skipjack is probable candidate Block size = 64 bits Key length = 80 bits No. of Rounds = 32 More No. of Rounds More time needed to crack the key

28. TinySec: a link layer encryption mechanism four main aims – Access Control, Integrity, Confidentiality, Easy of use. Implements Skipjack in CBC mode. Link layer Encryption A B

29. SKIPJACK Encryption SKIPJACK is a 64-bit codebook utilizing an 80-bit cryptovariable (Key) SKIPJACK encrypt/decrypt 4-word (64-bit) data blocks by alternating between the two stepping rules (A and B) The algorithm requires 32 steps (rounds)

30. Data sensing and Data forwarding Temperature Temperature Temperature

32. 1: micaz Motes

33. 2: MTS 400/420 Sensor Board

34. 3: MIB 520 gateway

36. Components A component is a black box specified by interface(s) Interfaces define a set of logically related I/O functions calledcommands and events Components use and provide interfaces Components are statically wired together based on their interfaces StdControl.nc interface StdControl { command result_t init(); command result_t start(); command result_t stop(); } Clock.nc interface Clock { command result_tsetRate( char interval, char scale); event result_t fire(); }

37. Commands and Events commands deposit request parameters into the frame are non-blocking need to return status postpone time consuming work by posting a task can call lower level commands events can call commands, signal events, post tasks can Not be signaled by commands preempt tasks, not vice-versa interrupt trigger the lowest level events deposit the information into the frame { ... status =callCmdName(args) ... } commandCmdName(args) { ... return status; } event EvtName(args) { ... return status; } { ... status =signalEvtName(args) ... }

38. Events and Tasks Tasks: Time flexible Longer background processing jobs … Hardware event handlers Time critical Shorter duration (hand off to task if need be) Interrupts task and other hardware handler. Last-in first-out semantics (no priority among events) executed in response to a hardware interrupt

39. Data Memory Model • STATIC memory allocation! – No heap (malloc) – No function pointers • Global variables – Available on a per-frame basis • Local variables – Saved on the stack – Declared within a method

40. Inter-Node Communication General Idea -Sender

41. Header (5) Payload (29) CRC (2) Sync TOS Active Messages typedefstructTOS_Msg{ // the following are transmitted uint16_t addr; uint8_t type; uint8_t group; uint8_t length; int8_t data[TOSH_DATA_LENGTH]; uint16_t crc; // the following are not transmitted uint16_t strength; uint8_t ack; uint16_t time; uint8_t sendSecurityMode; uint8_t receiveSecurityMode; } TOS_Msg; Message is “active” because it contains the destination address, group ID, and type. ‘group’: group IDs create a virtual network The address is a 16-bit value specified by “make” “length” specifies the size of the message . “crc” is the check sum

42. Working StdControl.init() StdControl.start() Timer.start(REPEAT, 100) Timer.fired() Post Task Filldata() Timer.Stop()

43. MIB520 USB INTERFACE BOARD The MIB520 provides USB connectivity to the IRIS and MICA family of Motes for communication and in-system programming. It supplies power to the devices through USB bus.

44. Hardware Setup