SPRAHN Secure Protected Rewards in Ad Hoc

SPRAHN: Secure & Protected Rewards in Ad Hoc Networks for ECE 695 – Mobile Wireless Networking Charles D. Fico April 27 th 2006

Introduction l Rewards have been shown to cause fair play via game theory l Compensates intermediate nodes (INs) for loss of limited resources l Battery power l CPU Time l Memory Resources

Introduction l SPRAHN: Secure & Protected Rewards in Ad Hoc Networks l Considers MANET as an internet link l Previous work centers on local MANET reward

Background - Cryptography l Three cryptographic means will be used for the secure rewards l AES-196 l RSA for Symmetric encryption for public key or Asymmetric encryption l El. Gamal key agreement for key exchange

Background – Cryptography: AES l Advanced Encryption Standard –Rijndael l Winner of NIST standardization search l AES is a block cipher & supports l l l 128 bit blocks 128, 196 or 256 bit keys. AES key levels >= 192 bits satisfies TOP SECRET information security for decades

Background – Cryptography: RSA l RSA developed by Rives, Shamir and Adleman at MIT in 1977 l Based on building two exponents which are inverses modulo a composite prime N. l Recent concerns of 1024 bit key security l While 2046 bit keys are currently safe, 4096 bit provide a standard having longevity >= AES-192

Background – Cryptography: El. Gamal l Based on Diffie-Hellman key agreement l Uses a Trusted Authority (TA) to provide public key l TA can be in the form of a signed/verified certificate

Background – Other Reward Systems l Deal with internal, local MANET, rewards and peer reviews l Many are unspecific about what the reward is; It is something good though l Rewards for ferrying traffic external to the network is not covered

SPRAHN Operation l Reward Link Initialization l Reward Link Refresh l Reward Outline l Key acquisition

Reward Link Initialization l Setup of the reward link establishes INs along the path from the local node to the MANET boundary node l Uses current routing algorithm active in the MANET l Major change required is memorization and propagation of boundary nodes addresses & public

Reward Link Initialization l Routes too & from the boundary node may change l Boundary nodes should remain the same, since they are less-mobile or non-mobile backbone attachments to external networks for the local MANET

Reward Link Initialization l Reward links are established internal node of the local MANET sending/receiving packets external to the local MANET l Initiated on local node preparing to send external packet or boundary node notifying of incoming external packet

Reward Link Initialization l In the unlikely event that a boundary node receives a packet bound for an external connection for which there is no reward link from the sender l Boundary node can issue a reward link request from the sender of the packet while suspending propagation of the packet. l Protects the network from nodes accidentally or maliciously not setting up Reward Links for packets to be sent outbound

Reward Link Initialization l Boundary nodes may reuse valid reward links with local MANET node same for different external nodes. l Allows for decrease in network overhead l Via public key encryption between internal and boundary nodes, an AES-192 encryption key is agreed upon for subsequent exchange of data packets for the reward link

Reward Link Refresh - Rewards l Local node in MANET connected with reward link is responsible party l Keep alive messages contain number of inbound & outbound messages sent, time stamp and sequence number. l Keep alive messages are AES-192 encrypted

Reward Link Refresh - Route l Based on active mobility (rate of route breaks) dictate local nodes boundary node route refreshes l Just as in reward link initialization but noted as an reward link update

Reward Outline l Nodes entering network receive boundary node list l Node that entered network notifies/registers with a boundary node via a time stamped login message encrypted with the boundary nodes public key l Node is ready to start collecting unused rewards and gain new rewards

Reward Outline l Based on weighted number of packets l Packet weight is determined by size l Downstream & Upstream packets are counted

Reward Outline l Maximum bandwidth for bonus is double normal bandwidth l Nodes are priority rated on size of unused reward l Reward collectable based on % of network load

Key Acquisition l New Node – one which has never acquired reward specifications on this network before; node requiring clean start l New node should be able to participate ASAP l Needs public key for itself

Key Acquisition l Upon entering MANET boundary node information/address will be supplied l New node connects with a boundary node to subscribe for reward membership and receives boundary nodes certificate l Use El. Gamal based key acquisition with public key from boundary certificate

Key Acquisition l Boundary node propagates information to other boundary nodes via a common AES 192 key which was exchanged via boundary node public keys

Conclusion l SPRAHN: Secure & Protected Rewards in Ad Hoc Networks l Rewards are based on traffic too and from external sources l Rewards are bandwidth specific

References 1) C. D. Fico, “SPRAHN: Secure & Protected Rewards in Ad Hoc Networks”, IUPUI, IN, April, 2006 2) Y. Zhang, W. Lou, and Y. Fang, “SIP: A Secure Incentive Protocol against Selfishness in Mobile Ad Hoc Networks”, IEEE Communications Society, WCNC, 2004. P. Engelstad, D. V. Thanh, and G. Egeland, “Name Resolution in On. Demand MANETs and over External IP Networks”, Univ. of Oslo, United Kingdom. Qi He, D. Wu, and P. Khosla, “SORI: A Secure and Objective Reputationbased Incentive Scheme for Ad-hoc Networks”, Carnegie Mellon Univ. , Dept. of Electrical & Computer Engineering, Gainesville, FL 32611. J. Pieprzyk, T. Hardjono, and J. Seberry, “Fundamentals of Computer Security”, Springer-Verlag Berlin Heidelberg, 2003. Wikipedia – Advanced Encryption Standard, http: //en. wikipedia. org/wiki/Advanced_Encryption_Standard. Wikipedia – RSA, http: //en. wikipedia. org/wiki/RSA. Wikipedia – El. Gamal encryption, http: //en. wikipedia. org/wiki/El. Gamal 3) 4) 5) 6) 7) 8)

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