Transcript Secure & Protected Rewards in Ad Hoc Networks, by Charles D. Fico

SPRAHN: Secure &
Protected Rewards in Ad
Hoc Networks
for
ECE695 – Mobile Wireless Networking
Charles D. Fico
April 27th 2006
Introduction

Rewards have been shown to cause fair
play via game theory

Compensates intermediate nodes (INs) for
loss of limited resources
Battery power
 CPU Time
 Memory Resources

Introduction

SPRAHN: Secure & Protected Rewards in
Ad Hoc Networks

Considers MANET as an internet link

Previous work centers on local MANET
reward
Background - Cryptography

Three cryptographic means will be used
for the secure rewards

AES-196 for Symmetric encryption

RSA for public key or Asymmetric encryption

ElGamal key agreement for key exchange
Background – Cryptography: AES

Advanced Encryption Standard –Rijndael

Winner of NIST standardization search

AES is a block cipher & supports



128 bit blocks
128, 196 or 256 bit keys.
AES key levels >= 192 bits satisfies TOP
SECRET information security for decades
Background – Cryptography: RSA

RSA developed by Rives, Shamir and Adleman
at MIT in 1977

Based on building two exponents which are
inverses modulo a composite prime N.

Recent concerns of 1024 bit key security

While 2046 bit keys are currently safe, 4096 bit
provide a standard having longevity >= AES-192
Background – Cryptography:
ElGamal

Based on Diffie-Hellman key agreement

Uses a Trusted Authority (TA) to provide
public key

TA can be in the form of a signed/verified
certificate
Background – Other Reward
Systems

Deal with internal, local MANET, rewards
and peer reviews

Many are unspecific about what the
reward is; It is something good though

Rewards for ferrying traffic external to the
network is not covered
SPRAHN Operation

Reward Link Initialization

Reward Link Refresh

Reward Outline

Key acquisition
Reward Link Initialization

Setup of the reward link establishes INs along
the path from the local node to the MANET
boundary node

Uses current routing algorithm active in the
MANET

Major change required is memorization and
propagation of boundary nodes addresses &
public
Reward Link Initialization

Routes too & from the boundary node may
change

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

Reward links are established internal node
of the local MANET sending/receiving
packets external to the local MANET

Initiated on local node preparing to send
external packet or boundary node notifying
of incoming external packet
Reward Link Initialization

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

Boundary node can issue a reward link request
from the sender of the packet while suspending
propagation of the packet.

Protects the network from nodes accidentally or
maliciously not setting up Reward Links for
packets to be sent outbound
Reward Link Initialization

Boundary nodes may reuse valid reward links
with local MANET node same for different
external nodes.

Allows for decrease in network overhead

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

Local node in MANET connected with
reward link is responsible party

Keep alive messages contain number of
inbound & outbound messages sent, time
stamp and sequence number.

Keep alive messages are AES-192
encrypted
Reward Link Refresh - Route

Based on active mobility (rate of route
breaks) dictate local nodes boundary node
route refreshes

Just as in reward link initialization but
noted as an reward link update
Reward Outline

Nodes entering network receive boundary node
list

Node that entered network notifies/registers with
a boundary node via a time stamped login
message encrypted with the boundary nodes
public key

Node is ready to start collecting unused rewards
and gain new rewards
Reward Outline

Based on weighted number of packets

Packet weight is determined by size

Downstream & Upstream packets are
counted
Reward Outline

Maximum bandwidth for bonus is double
normal bandwidth

Nodes are priority rated on size of unused
reward

Reward collectable based on % of network
load
Key Acquisition

New Node – one which has never
acquired reward specifications on this
network before; node requiring clean start

New node should be able to participate
ASAP

Needs public key for itself
Key Acquisition

Upon entering MANET boundary node
information/address will be supplied

New node connects with a boundary node
to subscribe for reward membership and
receives boundary nodes certificate

Use ElGamal based key acquisition with
public key from boundary certificate
Key Acquisition

Boundary node propagates information to
other boundary nodes via a common AES192 key which was exchanged via
boundary node public keys
Conclusion

SPRAHN: Secure & Protected Rewards in
Ad Hoc Networks

Rewards are based on traffic too and from
external sources

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 OnDemand 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 – ElGamal encryption, http://en.wikipedia.org/wiki/ElGamal
3)
4)
5)
6)
7)
8)
More Questions??