SPRAHNSPRAHN: Secure & : Secure & Protected Rewards in Ad Protected Rewards in Ad

Hoc NetworksHoc Networks

forforECE695 – Mobile Wireless NetworkingECE695 – Mobile Wireless Networking

Charles D. FicoCharles D. Fico

April 27April 27thth 2006 2006

IntroductionIntroduction

Rewards have been shown to cause fair Rewards have been shown to cause fair play via game theoryplay via game theory

Compensates intermediate nodes (INs) for Compensates intermediate nodes (INs) for loss of limited resourcesloss of limited resourcesBattery powerBattery powerCPU TimeCPU TimeMemory ResourcesMemory Resources

IntroductionIntroduction

SPRAHN: Secure & Protected Rewards in SPRAHN: Secure & Protected Rewards in Ad Hoc NetworksAd Hoc Networks

Considers MANET as an internet linkConsiders MANET as an internet link

Previous work centers on local MANET Previous work centers on local MANET rewardreward

Background - CryptographyBackground - Cryptography

Three cryptographic means will be used Three cryptographic means will be used for the secure rewardsfor the secure rewards

AES-196 for Symmetric encryptionAES-196 for Symmetric encryption

RSA for public key or Asymmetric encryptionRSA for public key or Asymmetric encryption

ElGamal key agreement for key exchangeElGamal key agreement for key exchange

Background – Cryptography: AESBackground – Cryptography: AES Advanced Encryption Standard –RijndaelAdvanced Encryption Standard –Rijndael

Winner of NIST standardization searchWinner of NIST standardization search

AES is a block cipher & supportsAES is a block cipher & supports 128 bit blocks128 bit blocks 128, 196 or 256 bit keys. 128, 196 or 256 bit keys.

AES key levels >= 192 bits satisfies TOP AES key levels >= 192 bits satisfies TOP SECRET information security for decadesSECRET information security for decades

Background – Cryptography: RSABackground – Cryptography: RSA

RSA developed by Rives, Shamir and Adleman at RSA developed by Rives, Shamir and Adleman at MIT in 1977MIT in 1977

Based on building two exponents which are Based on building two exponents which are inverses modulo a composite prime N. inverses modulo a composite prime N.

Recent concerns of 1024 bit key securityRecent concerns of 1024 bit key security

While 2046 bit keys are currently safe, 4096 bit While 2046 bit keys are currently safe, 4096 bit provide a standard having longevity >= AES-192provide a standard having longevity >= AES-192

Background – Cryptography: Background – Cryptography: ElGamalElGamal

Based on Diffie-Hellman key agreementBased on Diffie-Hellman key agreement

Uses a Trusted Authority (TA) to provide Uses a Trusted Authority (TA) to provide public keypublic key

TA can be in the form of a signed/verified TA can be in the form of a signed/verified certificatecertificate

Background – Other Reward Background – Other Reward SystemsSystems

Deal with internal, local MANET, rewards Deal with internal, local MANET, rewards and peer reviewsand peer reviews

Many are unspecific about what the Many are unspecific about what the reward is; It is something good thoughreward is; It is something good though

Rewards for ferrying traffic external to the Rewards for ferrying traffic external to the network is not coverednetwork is not covered

SPRAHN OperationSPRAHN Operation

Reward Link InitializationReward Link Initialization

Reward Link RefreshReward Link Refresh

Reward OutlineReward Outline

Key acquisitionKey acquisition

Reward Link InitializationReward Link Initialization

Setup of the reward link establishes INs along Setup of the reward link establishes INs along the path from the local node to the MANET the path from the local node to the MANET boundary node boundary node

Uses current routing algorithm active in the Uses current routing algorithm active in the MANETMANET

Major change required is memorization and Major change required is memorization and propagation of boundary nodes addresses & propagation of boundary nodes addresses & publicpublic

Reward Link InitializationReward Link Initialization

Routes too & from the boundary node may Routes too & from the boundary node may changechange

Boundary nodes should remain the same, Boundary nodes should remain the same, since they are less-mobile or non-mobile since they are less-mobile or non-mobile backbone attachments to external backbone attachments to external networks for the local MANET networks for the local MANET

Reward Link InitializationReward Link Initialization

Reward links are established internal node Reward links are established internal node of the local MANET sending/receiving of the local MANET sending/receiving packets external to the local MANET packets external to the local MANET

Initiated on local node preparing to send Initiated on local node preparing to send external packet or boundary node notifying external packet or boundary node notifying of incoming external packetof incoming external packet

Reward Link InitializationReward Link Initialization In the unlikely event that a boundary node In the unlikely event that a boundary node

receives a packet bound for an external receives a packet bound for an external connection for which there is no reward link from connection for which there is no reward link from the senderthe sender

Boundary node can issue a reward link request Boundary node can issue a reward link request from the sender of the packet while suspending from the sender of the packet while suspending propagation of the packet. propagation of the packet.

Protects the network from nodes accidentally or Protects the network from nodes accidentally or maliciously not setting up Reward Links for maliciously not setting up Reward Links for packets to be sent outbound packets to be sent outbound

Reward Link InitializationReward Link Initialization

Boundary nodes may reuse valid reward links Boundary nodes may reuse valid reward links with local MANET node same for different with local MANET node same for different external nodes. external nodes.

Allows for decrease in network overhead Allows for decrease in network overhead

Via public key encryption between internal and Via public key encryption between internal and boundary nodes, an AES-192 encryption key is boundary nodes, an AES-192 encryption key is agreed upon for subsequent exchange of data agreed upon for subsequent exchange of data packets for the reward link packets for the reward link

Reward Link Refresh - RewardsReward Link Refresh - Rewards

Local node in MANET connected with Local node in MANET connected with reward link is responsible partyreward link is responsible party

Keep alive messages contain number of Keep alive messages contain number of inbound & outbound messages sent, time inbound & outbound messages sent, time stamp and sequence number.stamp and sequence number.

Keep alive messages are AES-192 Keep alive messages are AES-192 encryptedencrypted

Reward Link Refresh - RouteReward Link Refresh - Route

Based on active mobility (rate of route Based on active mobility (rate of route breaks) dictate local nodes boundary node breaks) dictate local nodes boundary node route refreshesroute refreshes

Just as in reward link initialization but Just as in reward link initialization but noted as an reward link updatenoted as an reward link update

Reward OutlineReward Outline

Nodes entering network receive boundary node Nodes entering network receive boundary node listlist

Node that entered network notifies/registers with Node that entered network notifies/registers with a boundary node via a time stamped login a boundary node via a time stamped login message encrypted with the boundary nodes message encrypted with the boundary nodes public keypublic key

Node is ready to start collecting unused rewards Node is ready to start collecting unused rewards and gain new rewardsand gain new rewards

Reward OutlineReward Outline

Based on weighted number of packetsBased on weighted number of packets

Packet weight is determined by sizePacket weight is determined by size

Downstream & Upstream packets are Downstream & Upstream packets are countedcounted

Reward OutlineReward Outline

Maximum bandwidth for bonus is double Maximum bandwidth for bonus is double normal bandwidthnormal bandwidth

Nodes are priority rated on size of unused Nodes are priority rated on size of unused rewardreward

Reward collectable based on % of network Reward collectable based on % of network loadload

Key AcquisitionKey Acquisition

New Node – one which has never New Node – one which has never acquired reward specifications on this acquired reward specifications on this network before; node requiring clean startnetwork before; node requiring clean start

New node should be able to participate New node should be able to participate ASAPASAP

Needs public key for itselfNeeds public key for itself

Key AcquisitionKey Acquisition

Upon entering MANET boundary node Upon entering MANET boundary node information/address will be suppliedinformation/address will be supplied

New node connects with a boundary node New node connects with a boundary node to subscribe for reward membership and to subscribe for reward membership and receives boundary nodes certificatereceives boundary nodes certificate

Use ElGamal based key acquisition with Use ElGamal based key acquisition with public key from boundary certificatepublic key from boundary certificate

Key AcquisitionKey Acquisition

Boundary node propagates information to Boundary node propagates information to other boundary nodes via a common AES-other boundary nodes via a common AES-192 key which was exchanged via 192 key which was exchanged via boundary node public keysboundary node public keys

ConclusionConclusion

SPRAHN: Secure & Protected Rewards in SPRAHN: Secure & Protected Rewards in Ad Hoc NetworksAd Hoc Networks

Rewards are based on traffic too and from Rewards are based on traffic too and from external sourcesexternal sources

Rewards are bandwidth specificRewards are bandwidth specific

ReferencesReferences1)1) C. D. Fico, “SPRAHN: Secure & Protected Rewards in Ad Hoc C. D. Fico, “SPRAHN: Secure & Protected Rewards in Ad Hoc

Networks”, IUPUI, IN, April, 2006Networks”, IUPUI, IN, April, 2006

2)2) Y. Zhang, W. Lou, and Y. Fang, “SIP: A Secure Incentive Protocol Y. Zhang, W. Lou, and Y. Fang, “SIP: A Secure Incentive Protocol against Selfishness in Mobile Ad Hoc Networks”, IEEE Communications against Selfishness in Mobile Ad Hoc Networks”, IEEE Communications Society, WCNC, 2004.Society, WCNC, 2004.

3)3) P. Engelstad, D. V. Thanh, and G. Egeland, “Name Resolution in On-P. Engelstad, D. V. Thanh, and G. Egeland, “Name Resolution in On-Demand MANETs and over External IP Networks”, Univ. of Oslo, United Demand MANETs and over External IP Networks”, Univ. of Oslo, United Kingdom.Kingdom.

4)4) Qi He, D. Wu, and P. Khosla, “SORI: A Secure and Objective Reputation-Qi He, D. Wu, and P. Khosla, “SORI: A Secure and Objective Reputation-based Incentive Scheme for Ad-hoc Networks”, Carnegie Mellon Univ., based Incentive Scheme for Ad-hoc Networks”, Carnegie Mellon Univ., Dept. of Electrical & Computer Engineering, Gainesville, FL 32611.Dept. of Electrical & Computer Engineering, Gainesville, FL 32611.

5)5) J. Pieprzyk, T. Hardjono, and J. Seberry, “Fundamentals of Computer J. Pieprzyk, T. Hardjono, and J. Seberry, “Fundamentals of Computer Security”, Springer-Verlag Berlin Heidelberg, 2003.Security”, Springer-Verlag Berlin Heidelberg, 2003.

6)6) Wikipedia – Advanced Encryption Standard, Wikipedia – Advanced Encryption Standard, http://http://en.wikipedia.org/wiki/Advanced_Encryption_Standarden.wikipedia.org/wiki/Advanced_Encryption_Standard..

7)7) Wikipedia – RSA, Wikipedia – RSA, http://http://en.wikipedia.org/wiki/RSAen.wikipedia.org/wiki/RSA..8)8) Wikipedia – ElGamal encryption, Wikipedia – ElGamal encryption, http://http://en.wikipedia.org/wiki/ElGamalen.wikipedia.org/wiki/ElGamal

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