60-564 Security

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60-564 Security Privacy on the
InternetInstructor Dr. AggarwalSurvey

• New Developments on Ad-hoc Network Security
• Presenters
• Amar B. Patel , Mohammed F. Mokbel Shushan Zhao
• November 25th , Fall 2007
• School of Computer Science
• University of Windsor

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Outline of the Presentation

• Introduction to MANET
• Survey of routing protocols in MANET
• AODV protocol
• SAODV protocol
• Fuzzy Logic- based Security Level( FLSL) Routing
  Protocol
• Feature of FLSL
• Weakness of FLSL
• Our Improvement to FLSL
• Adding more Factor to Consideration
• Weight Moving Average of Security Level
• Applying PGP to Build a Self-Adjusted Security
  Architecture
• Self Adjusted Security Architecture for Mobile.
• Weakness and Possible Improvements
• Discussion and Conclusion

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Survey of routing protocols in MANET

• Mobile ad hoc network (MANET) is a relatively new
  innovation in the field of wireless technology
• Most of research focus on routing and do not
  concentrate much on other related issues, such as
  security
• Consequently, current mobile ad-hoc networks do
  not have any strict security policy, this could
  possibly lead active attackers to easily exploit
  or possibly disable the mobile ad-hoc network.

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Survey of routing protocols in MANET

• AODV protocolAd hoc On-demand Distance Vector
  protocol (AODV) AODV is a method of routing
  messages between mobile nodes. It allows these
  mobile computers, or nodes, to pass messages
  through their neighbours to nodes with which they
  cannot directly communicate. AODV does this by
  discovering the routes along which messages can
  be passed.
• SAODV protocol It is an extension of the AODV
  protocol. SAODV use some new extension message
  protect the routing messages of the plain AODV
  protocol. In these extension messages there is a
  signature created by digesting the AODV packet
  using the private key of the original sender of
  the Routing message.

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Survey of routing protocols in MANET

• SAODV protocol also has more procedures/operations
  in the routing discovering comparing with AODV
  protocol
• When a RREQ is sent, the sender signs the
  message. Neighbour nodes verify the signature
  before creating or updating a reverse route to
  that host. And only if the signature is fine they
  store the reverse route
• The final destination node signs the RREP with
  its private key. Intermediate and final nodes,
  again verify the signature before creating or
  updating a route to that host, also storing the
  signature with the route entry.

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Weakness of AODV SAODV Protocol

• In recent time, most of secure routing protocols
  focus on the key management, authentication and
  encryption algorithm
• These traditional routing protocols such as such
  as SAODV , SRP and SAR will fail to efficiently
  adapt to a higher security level routing
  selection
• Since the security level and selection of route
  are not part of their normal operation.
  Therefore, special routing protocols are needed
  for ad-hoc networks.

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Fuzzy Logic- based Security Level( FLSL) Routing
Protocol

• FLSL contains the way of determing the
  security-level of an individual mobile host in
  MANETs, and the algorithm to decide which route
  has the best security-level.
• FLSL has three kinds of message Route Request
  (RREQ), Route Reply (RREP) and Route Error
  (RERR).

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MODIFIED FEATURES of FLSL

• Message Packet Format
• RREQThe Security Level field is a new inserted
  field compared with RREQ messages in AODV
  protocol and SAODV protocol, which indicates the
  lowest security level of passed-by nodes. The
  initial Security Level field value of any RREQ
  message is set by source node and equal with the
  security level value of source code.

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MODIFIED FEATURES of FLSL

• RREPThe Security Level field is a new inserted
  field compared with RREP messages in AODV
  protocol and SAODV protocol, which indicates the
  security level value of selected route. The
  initial Security Level field value of any RREP
  message is set by the node which unicast RREP
  back to source node.

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NEW FEATURES of FLSL

• Security-Level of Mobile Host
• Fuzzy Logic AlgorithmIn MANET environment, the
  security level of individual mobile host is
  related closely with the difficulty of decrypting
  its secret key through brute-force attack. It is
  obvious that the security of secret key relies on
  the key length and the changing frequency of
  keys. In other words, the security-level of a
  mobile host is a function of multiple variables
  or the Security-Level is affected by many
  conditions.
• Security-Level Based RoutingFLSL protocol
  discovers and maintains only needed routes unlike
  traditional proactive protocols which maintain
  all routes regardless of their usage.
• Route DiscoveryThe security-Level of a route is
  decided by the node which has the lowest
  Security-Level in that route. So compared with
  the lowest Security-Level in other routes, the
  lowest security level in the highest security
  level route is higher.

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Security-Level of Mobile Host

• Security-Level parameters
• Fuzzy membership function
• Secret key length (l) Longer the secret key is,
  stronger to defend serious brute force attack.
• Changing frequency of secret key (f) If mobile
  hosts secret key is changeable, the difficulty
  of decryption must be increased and security
  level of mobile hosts also gets enhanced.
• Amount of active neighbour hosts (n) More active
  neighbour hosts existing will increase the
  percentage of potential attackers existing.
• Security-Level of Mobile Host

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Security-Level of Mobile Host

• Fuzzy logic system rules

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Security-Level of Mobile Host
For each entry in rules table
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Security-Level of Mobile Host

• The security level of single host j

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Security-Level of Route

• Security-Level of Route
• Security-Level of Final Route

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RREQ Packet Transmission
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RREP Packet Transmission
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Simulation in NS2

• RREQ Packet Transmission (18 random nodes)

S Source Node D Destination Node Step 1Node
0?Node 10Step 2Node 10?Node 15 Node10?Node
4 Step 3 Node 4?Node 17 (RREQ4 is firstly
arrived packet) Step 4 Node 15?Node 17 (RREQ15
is secondly arrived packet) Two available
routes 0?10?15?17 0?10?4?17
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Simulation in NS2

• RREP Packet Transmission (18 random nodes) S
  Source Node
• D Destination Node
• Step 1 Node 17?Node 4 (RREP4 is firstly
  generated RREP packet)
• Step 2 Node 17?Node 15 (RREP15 is secondly
  generated RREP packet)
• Step 3 Node 15?Node 10
• Step 4 Node 4?Node 10
• Step 5 Node 10?Node 0 (The RREP15 arrived Node
  10 earlier than RREP4, Node 10 dropped RREP4
  because RREP15s DSN is greater than RREP4.
  Finally Node 10 sends RREP15 to Node 0)

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Simulation

• The author conducted simulation experiment on
  their work using NS-2.
• Simulations show that the FLSL routing protocol
  can improve security of mobile ad hoc networks.
• They state that the simulation indicates that
  FLSL could reliably select the data transmission
  route with the highest security level and
  self-adaptive and dynamically adjust the route
  updating without delay.
• On the other hand, the simulation also shows
  that FLSL consumes more time for route discovery
  process. The authors analyse the time
  compensation and claim it is affordable and
  reasonable.

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Our Improvement to FLSL

• Adding More Factors to Consideration
• We think the fuzzy logic parameters considered in
  this scheme are not
• thorough and complete. We propose to add more
  factors to take into
• account.
• Battery Indicator (b) A secure route should
  also be a reliable route. This requires all the
  nodes along this route have enough battery power.
  
• Link-quality Indicator (q) In the original
  scheme, the number of active neighbour hosts is
  taken into account, but the quality of links to
  these neighbours is not. We suggest using a
  link-quality indicator parameter combined with
  the number of active neighbours.
• Credibility Indicator (c) In a secured MANET,
  there should be some on-line monitoring system
  that monitors the behaviour of each node, and
  evaluate the credibility of each one. This
  credibility should be used to evaluated the
  security level of the node.
• etc.

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Our Improvement to FLSL

• Adding More Factors to Consideration
• With new parameters, the security level can be
  represented as
• We can define the fuzzy logic member functions
  for these new parameters, and calculate the
  weighted security level using

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Our Improvement to FLSL

• Weighted Moving Average of Security Level
• We suggest using weighted moving average of
  security level instead of a single time point
  value.
• In most systems the security level of a node
  fluctuates. This may arise from the position
  change of the moving node, the temporary
  interferences, and so on. The weighted moving
  average can filter off sharp fluctuation.
• There is always some delay to get the latest
  value of security level and it is impossible to
  get the value in the next time point, while the
  weighted moving average provides a good
  estimation of the security level value in the
  future.

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Our Improvement to FLSL

• Weighted Moving Average of Security Level
• Each node keeps a series of previous security
  level values SLn,
• SL(n-1) , , SL0 .
• The old, historical values need to be given
  lesser weight or forgotten in order to be
  able to estimate the latest value.
• For each value , we assign a weighted
  coefficient
• Wi (r gt1).
• The weights wi are indexed so that w0 is the
  weight of the last value, w1 the second last, and
  so on.
• The adjusted security level is

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Our Improvement to FLSL

• Weighted Moving Average of Security Level
• To reduce the memory requirement of the
  algorithm, we want to allow calculating SL
  without having to keep all the earlier samples in
  memory, by using the previous calculated result
  SL

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Our Improvement to FLSL

• Weighted Moving Average of Security Level
• Choosing an empirical value ,
  we get
• This is a simplified equation to calculate the
  security level of a node that only needs keeping
  one historical data item

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Self Adjusted Security Archit.

• Merging the clustering and threshold key
  management techniques.
• The dynamicity of MANET topology is reflected
  into the process of assigning to the nodes a
  public key.
• Divide the net into clusters.
• cluster heads (HA) are connected by virtual
  network.
• Share the PK of the CA(Central Authority)

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MANET Topology Security

• Certificate-based authentication scheme
• Distributed authentication T
• Resource awareness T
• Efficient certificate T
• Heterogeneous certification T
• Robust pre-authentication mechanism T

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Prposed Security Architectyre

• Bootstrapping
• Cluster head
• Gateway nodes
• Warrant nodes
• Regular nodes
• Key management
• Register phase Believed to be
  trustworthy
• CH Retirement

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Partitioning the Network into clusters

• Ad-hoc Net. S.A.

? ? ? a
? ? ? a
? ? ? a
? ? ? a
? ? ? a
? ? ? a
? ? ? a
? ? ? a
? ? ? a
? ? ? a
a CH ßWarrant node ? GW ? Regular
node
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Performance Evaluation

• Availability
• Register Time
• Packet Overhead
• The solution was fully decentralized to operate
  in a large scale mobile network.

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Weaknesses Possible Improvements

• The dynamicity of MANET topology creates a real
  need for security measurements.
• Its not sufficient to generalize this proposed
  arch. based on NS-2 only
• More theoretical than practical
• Graph is more complicated than what it seems
  (lots of additional parameters conceptual
  analysis)

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Cont.

• We propose an efficient mechanism for
  acquiring/releasing nodes existence by using a
  hash table
• Which contains all the nodes required parameters
  to indicate their present/initial status.
• This Hash Table should not be centralized in any
  way but partitioned and distributed over
  different clusters heads (as a special
  container).
• There is only one variable which indicated
  whether this node does it exist in this cluster
  or not.
• Therefore, this mechanism will just lessen the
  overhead in distributing the public/private keys
  over MANET clusters nodes.

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Cont.

• Using a strong hash function like SHA-1 in the
  Hash Table is a must to avoid collision.
• The HT should be encrypted using public key
  system
• And it has a tree structure like to manage all
  these nodes with their clusters.
• Actually, it is not easy to choose a balanced
  hash function which takes into account the
  computation and the time required to do a certain
  job because, simplicity, speed and strength are
  not a simple factors to combine them into a
  leveled scaled algorithm, especially in a MANET
  Network.

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Discussions Conclusion

• In this paper, we study some new ideas on MANET
  security published in last two years.
• Although these ideas are novel and promising,
  there exist some weaknesses and drawbacks in the
  proposed schemes which hinder the schemes to be
  applied generally.
• We propose some improvement on these ideas for
  fuzzy logic security routing, we suggest using
  more factors to assess the security level of a
  node, and assessing the security dynamically by
  taking time weighted moving average for
  PGP-based self-adjusted security architecture.

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Cont.

• we think the existing scheme is too
  resource-demanding and not scalable to large
  network we propose to use some optimized data
  structure, such as hash table, to lower down the
  resource requirement.
• Due to time limitation, we cannot implement our
  ideas for proof. However, by theoretical
  analysis, we believe if our proposals are
  employed in the original schemes, there would be
  significant improvement in the schemes.

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Questions

• ?

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References

• 1 Jing Nie, JiangchuaWen, Ji Luo, Xin He,
  Zheng Zhou, 2006, An adaptive fuzzy logic based
  secure routing protocol in mobile ad hoc
  networks, Fuzzy Sets and Systems
• 2 Lu Jin, Zhongwei Zhang and Hong Zhou,
  Deliberation and Implementation of Adaptive Fuzzy
  Logic Based Security Level Routing Protocol for
  Mobile Ad Hoc Network, Consumer Communications
  and Networking Conference, 2007
• 3 AZ Ghalwash, AAA Youssif, SM Hashad, R Doss,
  2007, Self Adjusted Security Architecture for
  Mobile Ad Hoc Networks, 6th IEEE/ACIS
  International Conference on Computer and
  Information Science (ICIS 2007)   pp. 682-687
• 4 P.Zimmermnn , "The Official PGP usrs guide",
  MIT Press, 1995