This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
• Ability to sustain sensor network functionality without any interruption.• Protocols and schemes should be designed with the target level of fault tolerance.
• May reach millions of sensor nodes in studying a phenomenon or stimuli,• Schemes tend to form clusters,• Each cluster may have a coverage area of less than 10 meter.• Each cluster may have several to hundred sensor nodes.• Density of sensor nodes is high,
• This is much less than the power consumption in communications.
For example a 100 million instructions per second processor can execute 3 million instructions by the energy cost of transmitting 1 KB a distance of 100 m.
• Therefore, local data processing is crucial in minimizing power consumption in a wireless sensor network.
• However, the energy cost of data processing is not negligible.
Antenna gain is a measure of the directionality of an antenna. Antenna gain is defined as the power output, in a particular direction, compared to that produced in any direction, compared to that in any direction by a perfect omnidirectional antenna.
Rarely used. Kopernicus satellites have one of these transponders. Used for some transmissions. In the future it will be more in use because the whole KU band will be used completely.
wherePt = signal power at the transmitting antennaPr = signal power at the receiving antenna = carrier wavelengthd = propagation distance between antennasc = speed of light (3 108 m/s)
Multiple Access with Collision Avoidance Wireless (MACAW)
V.Bharghavan, AV.Bharghavan, A..Demers, S.Shenker, L.Zhang, "MACAW: A Media Access Protocol for wireless LAN’s", in Proceedings of ACM Demers, S.Shenker, L.Zhang, "MACAW: A Media Access Protocol for wireless LAN’s", in Proceedings of ACM SIGCOMM’94, pp. 212-225, 1994.SIGCOMM’94, pp. 212-225, 1994.
Properties of Pseudo Noise Sequences Balance property : The difference in the number of 1s and -1s in a pseudonoise cannot be higher than one. -1 -1 -1 1 -1 -1 1 1 -1 1 -1 1 1 1 1 (15 chips, 7 of them are -1s, and 8 of them are 1s.)
Run property: 50% of runs must be -1 runs, and the other 50% must be 1 runs, and 1/2n of runs must be n length runs.
-1 -1 -1 1 -1 -1 1 1 -1 1 -1 1 1 1 1
(8 runs, 4 of them are -1 runs, and 4 of them are 1 runs.)
Auto-correlation property: The number of chips that are the same differs from those that are different by at most 1 when a pseudonoise is compared chip by chip with any cycle of shift of itself.
• Short codes can generally be transfered in the duration of a symbol. In IS-95, the length of short codes is 215-1, and they can be transferred in 26.67 seconds when chip rate is 1.2888 Mcps. They are generally used in downlink to identify cells or location areas in cellular networks.
• In IS-95, the length of long codes is 242-1, and they can
be transferred in 44.5 days when chip rate is 1.2888 Mcps. They are generally used in uplink to identify mobile terminals.
# of Terminals that can Share a Sequence• A good pseudonoise is different enough from any shifted version of itself. Shifting only one chip is enough to obtain a different pseudonoise from the original. However, the difference between the pseudonoises assigned to different terminals must be high enough to compensate the differences in propagation delays.
15.6 km
Chiprate = 3.6864 Mcps# of bits in maximal lengthcode generator n = 15
Example:
The length of sequence p=215-1=32767The delay for 15.6 km td=15.6/300000=0.052 msec# of chips that can betransferred in td s=0.0523,686.4=192 chips
The Advantages of CDMA• CDMA has a soft capacity limited by interference. The decrease in
interference will directly increase the capacity:• Voice channels are generally utilized 3/8 of time.• Multi-beamed and multisectored antennas can reduce the interference.
• In FDMA and TDMA, some capacity between frequency channels is wasted.
• In CDMA, all the frequencies can be reused in the neighboring cells.
• In FDMA and CDMA, the frequency channel must be changed during handoff, i.e., hard handoff. This is not necessary in CDMA, i.e.,soft handoff.
• CDMA needs power control which actually decreases the interference, and increases the capacity.
• CDMA naturally provides frequency diversity which means additional security and reliability especially for military systems.
whereS is the power of the signal at the receiverR is the bit rate of the channel (bps)N is the number of channels used for the voice traffic is the voice activity factor for the voice channelsM is the number of channels used for the constant bit rate traffic is all the other noise over the mediaB is the bandwidth of the channels (Hz).
PiconetF.Bennett, D.Clarke, J.B. Evans, A.Hopper, A.Jones, and D.Leask, “Piconet: Embedded mobile networking”, IEEE Personal Communications Magazine, vol. 4, no. 5, pp. 8–15, Oct. 1997.
Tseng et al.Y.Tseng, C.Hsu, and T.Hsieh, “Power-saving protocols for IEEE 802.11-based multi-hop ad hoc networks”, in Proceedings of the IEEE Infocom, New York, NY, June 2002, pp. 200–209.
SEEDEXR.Rozovsky and P.R.Kumar, “Seedex: A MAC protocol for ad hoc networks”, In Proceedings of the 2nd ACM International Symposium on Mobile ad hoc networking and computing, pages 67-75, New York, NY, USA, 2001. ACM Press.
RBARG.Holland, N.Vaidya, and P.Bahl, “A rate-adaptive MAC protocol for multi-hop wireless networks. In Proceedings of ACM MOBICOM'01, Rome, Italy, 2001.
OARB.Sadeghi, V.Kanodia, A.Sabharwal, and E.Knighlty, “Opportunistic Media Access for Multirate Ad Hoc Networks”, in Proceedings of ACM MobiCom'02 , Atlanta, GA, September 2002.
Woo & CullerA.Woo and D.Culler, “A transmission control scheme for media access in sensor networks”, in Proceedings of the ACM/IEEE International Conference on Mobile Computing and Networking, Rome, Italy, July 2001, pp. 221–235, ACM.
WW..Ye, JYe, J..Heidemann, and DHeidemann, and D..Estrin, “An energy-efficient mac protocol for wireless sensor networks”Estrin, “An energy-efficient mac protocol for wireless sensor networks”,, in Proceedings of the IEEE in Proceedings of the IEEE Infocom, New York, NY, June 2002, pp. 1567–1576.Infocom, New York, NY, June 2002, pp. 1567–1576.
• Each node obeys its neighbors’ schedule if one was heard, otherwise chooses and broadcasts one
• Schedule table is maintained locally and updated after receiving SYNC packets
TT..van Dam and Kvan Dam and K..Langendoen, Langendoen, ““An Adaptive Energy-Efficient MAC Protocol for Wireless Sensor NetworksAn Adaptive Energy-Efficient MAC Protocol for Wireless Sensor Networks””, , ACM SenSys, Los Angeles, CA, November, 2003.ACM SenSys, Los Angeles, CA, November, 2003.
• Clustering and synchronization as in S-MAC
• Adaptive duty cycle to handle load variations in time and location (i.e. near the sink)
E.-S.Jungand N.H.Vaidya, “A Power Control MAC Protocol for Ad Hoc Networks,” MOBICOM2002E.-S.Jungand N.H.Vaidya, “A Power Control MAC Protocol for Ad Hoc Networks,” MOBICOM2002, , SeptemberSeptember 200 20022..
a b c
hdf
eg
rmax
rmax
rmin
• RTS and CTS are transmitted at the maximum power (rmax).
• DATA and ACK are transmitted at the minimum power required (rmin).
• To improve the performance of BASIC scheme, the transmission power is periodically increased while a DATA frame is being transmitted.
Both open loop and closed loop, distributed, RSSI-based, fixed step size, discrete and independent.
SYNC: rmax
RTS: open loop, max(rab, rae, raf).CTS, ACK: open loop, max(rab, rbc, rbd).SDSH: open loop, max(rab, rae, raf).DATA: closed loop, rab.
P.C.Nar, E.Cayirci , “PCSMAC: A Power Controlled Sensor MAC Protocol for Wireless Sensor Networks,” EWSNP.C.Nar, E.Cayirci , “PCSMAC: A Power Controlled Sensor MAC Protocol for Wireless Sensor Networks,” EWSN 200 20055..
• Contention resolution schemes for packet radio networks.
• 2-hop neighborhood awareness is essential which requires a random access period for distributing one-hop neighbor information.
• Nodes unelected during a time slot switch to receive mode
L.Bao and J.J.Garcia-Luna-AcevesL.Bao and J.J.Garcia-Luna-Aceves, “, “A new approach to channel access scheduling for ad hoc networksA new approach to channel access scheduling for ad hoc networks”, ”, In In The seventh annual international conference on Mobile computing and networking 2001, pages 210-221, The seventh annual international conference on Mobile computing and networking 2001, pages 210-221, 2001.2001.
• Contention resolution scheme for wireless sensor networks inspired from NAMA/LAMA/PAMA
• Nodes unelected during a time slot switch to sleep mode, instead of receive mode
V. Rajendran, K. Obraczka, and J.J. Garcia-Luna-Aceves, “Energy-Efficient, Collision-Free Medium Access Control for Wireless Sensor Networks”, ACM SenSys, Los Angeles, CA, November, 2003.
• Integrated, collaborative approach that is part of the EYES project.
S.Dulman, L. van Hoesel, T.Nieberg, and P.Havinga, “Collaborative communication protocols for wireless sensor networks”, European research on middleware and architectures for complex and embedded cooperative systems, workshop held in conjunction with IEEE ISADS 2003, Pisa, Italy, pp. 3-7, ISBN- 0-7695-1876-1, April 2003.
A is down at the beginning. A comes up. 1 after 1 exc. 1 2 after 2 exc. 1 2 3 after 3 exc. 1 2 3 4 after 4 exc.
Algorithm rapidly reacts to good news.In N exchanges, everyone knows about the new router where the longest path is N hop.
A B C D E
A is up at the beginning. 1 2 3 4A goes down. 3 2 3 4 after 1 exc. 3 4 3 4 after 2 exc. 5 4 5 4 after 3 exc. 5 6 5 6 after 4 exc. 7 6 7 6 after 5 exc. 7 8 7 8 after 6 exc. 9 8 9 8 after 6 exc.It repeats until What is infinitive?It is the highest number of hop plus 1, if the paths are measured according to the number of hops.What if we use delay?
- no fixed infrastructure- multihop- no centralized administration- nodes act both as a host and a router - wireless medium- topology changes- resources are limited
Adhoc on demand distance vectorDynamic source routingLightweight mobile routingTemporally ordered routingAssociativity based routingSignal stability routing
• WRP uses both periodic and event triggered (in case of a link status change) update messages for topology maintenance. Update messages are exchanged among the neighboring nodes.
• Every node broadcasts a periodic update (HELLO message) reporting no changes if it does not report an update for a specific time period. Periodic updates are not acknowledged.
• Event triggered updates are broadcasted when topology changes are detected, and acknowledged by the related nodes.
• TORA has three basic functions:• Route creation• Route maintenance• Route erasure
• A height metric is used by the nodes in route creation and maintenance in order to establish a directed acyclic graph. The height metric is related with the logical time of link failure.
• Route erasure function uses a clear (CLR) packet throughout the network to erase invalid routes.
Categorization of Routing Protocols for Wireless Sensor Networks:(K. Akkaya, M. Younis, “A Survey on Routing Protocols for Wireless Sensor Networks,” Elsevier AdHoc Networks)
• Data centric protocolsFlooding, Gossiping, SPIN, SAR, Directed Diffusion, Energy Aware Routing, Rumor Routing, TEEN, APTEEN, CADR
•In LEACH, the nodes organize themselves into clusters.
•Sensors may elect themselves to be a local cluster head at any time with a certain probability.
•Each node access the network through the cluster head that requires minimum energy to reach.
W. R. Heinzelman, A. Chandrakasan, and H. Balakrishnan, “Energy-Efficient Communication Protocol for Wireless Microsensor Networks,'' IEEE Proceedings of the Hawaii International Conference on System Sciences, pp. 1-10, January, 2000.
• A sub-graph G of G’ is computed. G connects all nodes with minimum energy cost.
AA
BB
Connection A requires less energy than connection B because the power required to transmit between a pair of nodes increases as the nth power of the distance between them (n>=2).
• Energy Aware RoutingR.Shah, J. Rabaey, “Energy Aware Routing for Low Energy Ad Hoc Sensor Networks,” IEEE WCNC’02, Orlando, March 2002.
• Rumor RoutingD. Braginsky, D. Estrin, “Rumor Routing Algorithm for Sensor Networks,” ACM WSNA’02, Atlanta, October 2002.
• Threshold sensitive Energy Efficient sensor Network (TEEN)A. Manjeshwar, D.P. Agrawal, “TEEN: A Protocol for Enhanced Efficiency in Wireless Sensor Networks,” IEEE WCNC’02, Orlando, March 2002.
• Constrained Anisotropic Diffusion Routing (CADR)M. Chu, H.Hausecker, F.Zhao, “Scalable Information-Driven Sensor Querying and Routing for Ad Hoc Heterogeneous Sensor Networks,” International Journal of High Performance Computing Applications, Vol. 16, No. 3, August 2002.
• Power Efficient Gathering in Sensor Information Systems (PEGASIS)S. Lindsey, C.S. Raghavendra, “PEGASIS: Power Efficient Gathering in Sensor Information Systems,” IEEE Aerospace Conference, Montana, March 2002.
• Self Organizing ProtocolL. Subramanian, R.H. Katz, “An Architecture for Building Self Configurable Systems,” IEEE/ACM Workshop on Mobile Ad Hoc Networking and Computing, Boston, August 2000.
• Geographic Adaptive Fidelity (GAF)Y. Yu, J. Heideman, D. Estrin, “Geography-informed energy conservation for ad hoc routing,” MobiCom’01, Rome, July 2001.
• RMST is a transport layer protocol for directed diffusion.• RMST provides end-to-end data-packet transfer reliability.• RMST is a selective NACK-based protocol that can be configured for in-network caching and repair.• There are two modes for RMST: caching mode, non-caching mode.• In caching mode, a number of nodes along a reinforced path, path being used to convey the data to the sink by directed diffusion, are assigned as RMST nodes.
F. Stann, J.Wagner, “RMST: Reliable Data Transport in Sensor Networks,” SNPA 2003.
• Each RMST node caches the fragments identified by FragNo of a flow identified by RmstNo.• When a fragment is not received before the watchdog timer for the flow expires, a negative acknowledgement is sent backward.• The first RMST node that has the required fragment along the path retransmits the fragment.• In non-caching mode, sink is the only RMST node.• RMST relies on directed diffusion scheme for recovery from the failed reinforced paths.
• Three functions: pump, fetch, and report operations.• Every intermediate node maintains a data cache.• A node that receives a packet check its content against its local cache, and discards any duplicates.• If the received packet is new, the TTL field in the packet is decremented.• If the TTL field is higher than 0 after being decremented, and there is no gap in the packet sequence numbers, the packet is relayed after being delayed a random period.• A node goes to fetch mode once a sequence number gap is detected.• The node in fetch mode requests a retransmission from neighboring nodes.
C-Y Wan, A.T. Campbell, L. Krishnamurty, “PSFQ: A Reliable Transport Protocol for Wireless Sensor Networks,” WSNA’02
• ESRT is the first scheme that focuses on the end-to-end reliable event transfer.• The end-to-end event transfer reliability is controlled based on the reporting frequencies of sensor nodes.
Y. Sankarasubramaniam, O.B. Akan, I.F. Akyildiz, “ESRT: Event-to-Sink Reliable Transport in Wireless Sensor Networks,” Mobihoc’03
• Both ends know the threshold.• When the receiver finds out that the difference between the value in a new sensed data packet and in the previous packet is higher than the threshold, this indicates a critical data packet, and it acknowledges the receipt of the critical packet.• If the sender does not receive an acknowledgement for a critical packet during the timeout period, it retransmits the critical packet.
The following information is used to estimate the distance to a transmitter:
• Received power,• Transmitted power,• Path loss model.
RSSI method may be unreliable and inaccurate due to:• Multi-path effects,• Shadowing, scattering, and other impairments,• Non line of sight conditions.
Time of arrival method may also be unreliable and inaccurate due to multi-path effects and non line of sight conditions.
The beacon and the node needs to be synchronized.
The propagation speed of RF signals is too high for beacon based localization in sensor networks. Therefore signals with lower propagation speed such as ultrasound should be used.
• Temperature: Temperature variations during day may cause the clock speed up or down (a few microseconds per day). • Phase noise: Access fluctuation at the hardware interface, response variation of the operating system to interrupts, jitter in delay, etc.• Frequency noise: The frequency spectrum of a crystal has large sidebands on adjacent frequencies.• Asymmetric delay: The delay of a path may be different for each direction.• Clock glitches: Hardware or software anomalies may cause sudden jumps in time.
Offset (ο): Nodes may be started at different times. Therefore, Node A may have a clock CA different from the clock CB that Node B has when the network starts at time t0.
Skew (s): The factors like frequency noise and hardware may make the crystals of nodes are running at different frequencies. This causes clock skew, which may be ±30-40 part per million (ppm) for sensor node hardware. Skew may make times of two nodes get closer or further based on the offset. The skew related change per unit time t is constant.
Drift (d): The factors like temperature, phase, asymmetric delay and clock glitches may change the offset between two nodes in time. Since these factors are temporarily variable, the change in clock, called drift, per unit time is not a fixed value.
• It provides interfaces to access sensor hardware:
- getTemperature, turnOn
for location awareness:
- isNeighbor, getPosition
and for communication:
- tell, execute.
C-C Shen, et.al., “Sensor Information Networking Architecture and Applications”, C-C Shen, et.al., “Sensor Information Networking Architecture and Applications”, IEEE Personal Communications MagazineIEEE Personal Communications Magazine, pp. 52-59, , pp. 52-59, August 2001.)August 2001.)
N. Sadagopan, B. Krishnamachari, A. Helmy, “The Acquire Mechanism for Efficient Querying in Sensor Networks,” Elsevier Ad Hoc and Sensor Networks, 2004.
A. Helmy, “Mobility-Assisted Resolution of Queries in Large-Scale Mobile Sensor Networks” Special Issue Computer Networks (Elsevier) on Wireless Sensor Networks, 2003.
Mobility-Assisted Resolution of Queries in Large-Scale Mobile Sensor Networks
In area coverage the objective is to cover an area, which means for the sensing coverage problem to ensure every point in a given area can be observed, and for the communications coverage problem a node at any point in the area can access the network.
In point coverage the objective is to ensure that a given set of points are covered by the network.
In barrier coverage the objective is to ensure that there is no hidden path through the network, i.e., an intruder cannot go through the network without crossing the coverage area of at least one node.
-The nodes are assumed to be deployed randomly according to a distribution, and the minimum number of nodes that satisfies a given probability of coverage is determined.
-It is assumed that the nodes can be deployed at certain locations, and the location for each node is determined such that the maximum coverage for the given number of nodes can be achieved.
Eavesdrop: Tap the communication lines - wireless links are easier to tap- signals are sent to shorter distances in wireless ad hoc networks- challenges when multiple networks with different classification- privacy challenges- collection vs analysis
Traffic analysis: Traffic patterns and rates- friendship trees
- Traffic analysis at the physical layer: In this attack only the carrier is sensed and the traffic rates are analyzed for the nodes at a location.
- Traffic analysis in MAC and higher layers: MAC frames and data packets can be de-multiplexed and the headers can be analyzed. This can reveal the routing information, topology of the network and friendship trees.
- Traffic analysis by event correlation: Events like a detection in sensor network or transmission by an end user can be correlated with the traffic and more detailed information, e.g., routes, etc., can be derived.
- Active traffic analysis: For example, certain number of nodes can be destroyed, which stimulates the self organization in the network, and valuable data about the topology can be gathered.
- Node localization- Time synchronization- Data aggregation and fusion- Data correlation and association- Event and event boundary detection- Node management
Any event that diminishes a network capacity to perform its expected function correctly or in a timely manner
A DOS attack is characterized by:
- Malicious: It is carried out to prevent the network from fulfilling its intended functions. It is not accidental. Otherwise it is not in the domain of security but reliability and fault tolerance.
- Disruptive: It degrades the quality of services by the network.
- Asymmetric: The attacker puts much less effort comparing to the impact made on the network.
- In physical layer (jamming) either continuous or temporary and random
- In MAC layer:- Whenever an RTS signal is received, a signal that collides with the CTS signal is transmitted.- If the MAC scheme is based on the sleep and active periods, jamming only the active periods can continuously block the channel.- False RTS or CTS signals with long data transmission parameters are continuously sent out.- Acknowledgement spoofing, where an adversary sends false link layer acknowledgements.
DOS Against Routing Sinkhole: attractive malicious node
Blackhole: malicious node drops every packet Selective forwarding: malicious node does not forward every packet - Routing loop attack: Detour or sinkhole attacks to create routing loops - Sybil attack: A single node presents multiple identities - Rushing attack: An attacker disseminates route request and reply messages quickly throughout the network. - Attacks that exploit node penalizing schemes - Attacks to deplete network resources
• Build a security infrastructure between the nodes during the bootstrapping phase
• new nodes that can join the network can form a secure association with the nodes already in the network
• the trust infrastructure can be set up without the knowledge of the network topology
• the credential verification scheme should be strong enough to resist DoS attack and at the same time do not need large computational ability and memory
PKG chooses two large primes as private maser key, and publishesthe chosen and calulated public system parameters as shownPrivate Master Key : p, q (two large primes)Public system params:n = p·q (factorization is kept secret)e = large prime, gdc (e,φ(n)) = 1f = hash function
PKG
2 EXTRACTION
3 SIGNING
PKG
user
The user presents its identity, to PKGPKG returns the corresponding private key:gThe identity is related to g in the following wayg =i (mod n)
e
g
Alice Bob
e
f(t,m) (i, m, t, s)
4 VERIFICATION
The signature (s,t) of themessage m is verified by checking:
e f(t,m)S = i·t (mod n)
The security of Shamir’s IBS schem relies the difficulty of deciding g given g mod n when the factorization of n is unknowne
securechannel
The signature (s,t) of the message mis caculated as follows:
t = r , s =g·r (mod n) i : user id m : message s,t : signatrue r : random
Geographical Leashes: The source node S includes its location lS and the packet
transmission time tS as the geographical leash into its packet PS sent to
destination D.
S→D: lS, tS, PS
The clocks are synchronized to within ±Δ. The upper bound for the distance is db.
The node localization error upper bound is δ. The upper bound for the velocity in transmitting signals is v The node i that forwards the packet, which is at location li, and receives the
packet at time ti can check the following condition:
Temporal Leashes: The transmission and reception times of the packets are used for detecting wormholes. When a node A sends or forwards a packet to another node B, it also includes the transmission time tA into the packet PA.
A→B: tA, PA
Node B checks the difference dAB between the transmission time tA and reception
time tB of the packet.
If dAB is larger than a given threshold θ, it may indicate a wormhole attack.
Direct validation: A node directly verifies if the identity of a neighboring node is valid. For example, a node may assign each of its neighbors a separate channel to communicate, and ask them to transmit during a period. Then it checks these channels in a random order within that period. If a node is transmitting in its assigned channel, the node is a physical node. Indirect validation: Another trusted node provides the verification for the identity of the node. For example, every node may share a unique key with the base station. When two nodes need to establish a link between them, they verify each others identity through the base station by using these keys. Random key: Random keys assigned to nodes also provide security against sybil attacks.
Acknowledgements: Every intermediate node that forwards a packet waits for an acknowledgement from the next hope. If the next hope node does not return the same number of acknowledgements as the number of the packets sent, the node generates an alarm about the next hop node. Compromised nodes can generate acknowledgements also for the packets that they dropped which make this scheme fails. Moreover a malicious node can generate fake alarms to organize a DoS attack. Multipath routing: This requires at least link disjoint paths, where two paths may share some nodes but any link. Of course node disjoint paths, where two paths do not have any node in common, are better and reduce the risk of selective forwarding attack
- Base station floods a route request message- Use TESLA for authentication- Everynode appends its id and a MAC by using a secret key before forwarding the route request- Everynode returns a route reply to the base station message after waiting t- Base station verifies MAC, computes the routes, and send them to nodes
- Data Forwarding Phase<destination, source, immediate sender> Example:Route: S to D: S → a → b → c → D The forwarding table of a: <D, S, S> The forwarding table of b: <D, S, a> The forwarding table of b: <D, S, b>.
When a node A accesses the network first time or needs a certificate for route discovery, it requests the certificate from the trusted server T. The server T first authenticates the node A and sends a certificate to it:
T → A: certificateA
IPA is the IP address of Node A,
KA+ is the public key of A,
t is the time the certificate is created,e is the time that the certificate expires,
A node S that has a valid certificate can start a route discovery for another node D by broadcasting a route discovery packet (RDP):
where NS is a nonce, which is the sequence number, i.e., the source node S
monotonically increase the nonce each time it performs a route discovery, to ensure the freshness of the reply message expected from the destination D.
When a node receives an RDP message, it first decrypts the message, and then records the neighbor that sends the message as the next hop node for the source node of the message. If the node receives a reply message for this RDP, it just forwards the reply to the neighbor in this record. Finally, it encrypts the message by using its private key, appends its certificate and broadcasts the message.
When destination node D receives the route discovery message from the last node in the route, i.e., let it be C for our example, it first verifies the source’s signature, and then prepares a reply (REP) message and unicasts it to C:
ARIADNEARIADNE route discovery process starts with a ‘route request’ that has the following fields: - Route request - Source node - Destination node - Route request Id - Time interval - Hash chain: The hash value created by all the nodes in the route - Node list: The list of nodes in the route - MAC list: The list of the MAC values calculated by every node in the route Hash chain is computed first by the source node S as follows:
h0=MAC(KSD, REQUEST | S | D | id | ti)
After computing h0, source node initializes node list and MAC list fields as empty lists
ARIADNEEvery node that receives route request first checks <source, id> fields in its buffer. If this request has already been received, the new request is dropped. The node also checks the time interval. If it is too far in the future or the key associated with it is already disclosed, packet is discarded. Otherwise the receiving node modifies the hash chain hi. Assume that A is a node one hop from the source node S. It computes
h1 as follows:
h1=H(A, h0)
It also calculates its MAC value by using the next key KAti in the TESLA key chain,
adds it’s address and the MAC value into the ‘route request’ message and broadcasts it:
A → broadcast:{REQUEST, S, D, id, ti, h1, (A), (MA)}
ARIADNEWhen the destination node receives the ‘route request’, it checks the validity of the request by determining that the keys of the time interval are not disclosed yet, and the final hash chain is equal to
H(an, H(an-1, H(…..,H(a1, MAC(KSD, REQUEST | S | D | id | ti))….)))
where an is the address of the node at position n and there are n nodes in the node
list. If both of these conditions are hold, it indicates that the request is valid. Then the destination node D computes the destination MAC MD, prepares ‘route reply’
message and returns it along the source route that can be obtained by reversing the sequence of hops in the node list of the ‘route request’ message.
In the reverse path, every node waits until it can disclose its TESLA key. After than it appends its TESLA key and forwards to the next hop in the reverse path. When source receives the ‘route reply’ message, it verifies that each key and each MAC are valid. If they are, it accepts the ‘route reply’ message. Otherwise it discards the message. After this the route is maintained in the ‘route cache’ until a ‘route error’ message is received. When an intermediate node B that tries to forward a message to the next node C in the route fails, it generates the following ‘route error’ message and sends it to source node S along the reverse path.
Pathrater rates the links based on the reliability of the links and misbehaving knowledge of the nodes. Every node rates every other node in the network. When a link used successfully, its rate increases. If a link break occurs, the rate of the link decreases. High negative numbers are assigned to the nodes suspected misbehaving. Paths are rated averaging the link ratings along the path. When the source node has multiple options to a destination, it selects the path with the highest path rate. Paths that contain misbehaving nodes are avoided. When there is no misbehaving link free path to the destination, the source node initiates a ‘route request’ process.
To secure the integrity of hop count, a hash chain is formed by applying one way hash function H to a randomly selected seed value s. Before transmitting a route request (RREQ) or route reply (RREP) message the source sets hash value h to seed s. The maximum hop count is assigned the time to live value ttl, and then top hash value T is computed by applying hash function ttl times to seed s.
h=sT=Httl(s)
When a node i receives a message after i hops from the source node, it first checks if the following condition holds:
Since every intermediate node applies hash function H once to the hash value h in the message before relaying it, when H is applied ttl-i times to the current h, it should give top hash value T. Otherwise it indicates either the hash value h or hop count i is not correct. After this check, node i applies H to h and forwards it.
h=H(h) To protect the integrity of the other fields in the message the source node signs every thing but the hop count and hash value h fields, which are modified by every intermediate node.
SLSPA node V broadcasts its link state data by using an LSU packet.
V → broadcast:{TYPE, R, Zone_R, LSU_Seq, LSU_signature, Hops_Traversed, LS_Data} where Type is the packet type,R is the number of hops from the node to the zone boundary,Zone_R=HR(X),Hops_Traversed=H(X),X is a random number,H is the hash function that every node knows,LSU_Seq is the sequence number of the LSU packet,
Receiving nodes first validate the signature. If the LSU packet is valid, they can derive the link state information in the packet. Then they hash Hops_Traversed value in the LSU packet.
Hop_Traversed=H(Hop_Traversed) If the new Hop_Traversed value is equal to Zone_R value after hashing, it indicates that the packet is reached to the boundary of zone, and should not be forwarded further.
Quarantine region is the region in the coverage area of an anti-node.
anti-nodeanti-node
sensor nodesensor node
quarantine quarantine regionregion
quarantined sensor quarantined sensor nodenode
sensor sensor rangerange
Quarantine Region Scheme
(Coskun, V, Cayirci, E., Levi, A., Sancak, S., “Quarantine Region Scheme to Prevent Spam Attacks in Wireless Sensor Networks,” IEEE Transactions on Mobile Computing, Volume 5, No. 8, pp 1074-1086, August 2006.)
• d receives authenticated from b, and sends authenticated to j,
• o receives authenticated from l, and sends unauthenticated to p.
• o receives unauthenticated from n, and sends unauthenticated to p.
aa bbcc
ddee ffjjgg
hhii kk
ll mm
nn oocollectocollectorrpp
• Detecting an attack, and declaring a quarantine period,• Finding quarantined nodes,• Authentication in quarantine region,• Cancelling a quarantine period.
- The detecting beacon, requests a beacon signal, i.e., Breq, from another beacon node na, the target beacon node. Detecting beacon acts as it is not a beacon node.
n→na: Breq
- Target beacon sends the beacon signal, i.e., Bbeacon, which includes the location (xa, ya) of the target beacon na.
- Detecting beacon estimates the distance da to the location (xa, ya) of the target beacon based on the RSSI calculation.
-The detecting node knows its location, it can calculate the distance between itself and the target node location sent in Bbeacon. If the difference between the estimated distance da, and the calculated distance d is higher than the threshold τ, this may indicate that the target node is malicious.
1. Construct the set of faulty nodes Ω1.2. For each sensor Si not in Ω1, - Partition the N(Si) into sectors.- Calculate the difference dij for each sector.- Assign the largest dij as the new di for Si.- Recalculate the mean μ, standard deviation σ, and yi for N*(Si)-Ω1 and the new di.- If |yi|≥θ2 after recalculation, Si goes into the set of boundary nodes denoted by Ω2.
• X.800 • ITU-T recommendation• Security architecture for OSI• Define general security-related architectural elements • Establishes guidelines and constraints to improve existing
recommendations and/or to develop new recommendations
• IETF RFC2828 • Internet Security Glossary• Provides abbreviations, explanations, and recommendations
• Data integrity • Connection integrity with recovery• Connection integrity without recovery• Selective field connection integrity• Connectionless integrity• Selective field connectionless integrity
• Non-repudiation• Non-repudiation with proof of origin• Non-repudiation with proof of delivery
• Encryption • Using a longer IV (48 bits)• Increasing the key size from 40 to 128 bits• Renewing encryption key every 10,000 packets• Using per packet key mixing of the IV