Yanchao Zhang, Yuguang FangWireless Networks

2006.6

MMC Lab. 임동혁

Introduction Network architecture and system

models Entity authentication Incontestable billing of mobile users System Analysis Conclusions

Large-scale WMNAuthenticationBilling

Conventional solutionHome-foreign-domain Drawback

Time-consuming, expensive execution authentication

Bilateral service level agreement(SLA) No consideration about how to reward

intermediate users for packet forwarding

UPASSNo need SLA between WMN operatorsAuthentication

ID-based cryptography(IBC)User vs serving WMNUser vs user in the same WMN

Certificate-based cryptography(CBC)Universal verifiability of passes

Billing Digital signature & one-way hash-chain Realtime micropayment approach

AssumptionsMesh router sends packets in one hop to all

users in its coverageA mobile user transmits packets multiple

hops to a mesh routerAll communications pass through a mesh

router

User-broker-operator relationship model

Broker

WMNOperato

r

User

Universal

pass

Universal

pass

Network

service

Network

service

payment

payment

usage data

usage data

Trust modelCBC for certification of trust-domain

parameter IBC in each trust domain

Trust domain setupTrust-domain parameter

(Hash function, domain-public-key, …) Certification of

domain parameterDomain-params are used

as public key

Pass modelRouter

R-NAI : routerID@operater_domain R-pass : (R-NAI, expiry-date) R-key : kH1(R-pass) k : operator’s domain-master-secret (R-pass, R-key): IBC public & private key pair

User U-NAI : userID@broker_domain U-pass : (U-NAI, expiry-date, otherTerms) U-key : kH1(U-pass) k : broker’s domain-master-secret (U-pass, U-key) : IBC public & private key pair

Pairwise shared keyUser-router authentication

Inter-domain authentication Intra-domain authentication

User-user authentication

Inter-domain authenticationU and R possesses each other’s authentic

domain-paramsProcedure

(1) (2) (3)

(4) (5) shared key :

Intra-domain authenticationBetween same WMN domainProcedure

(1) (2) (3)

Computationally efficient Fast hash instead of signature and encryption

User-user authenticationGet paid for his packet forwardingPairwise shared keys

Symmetric-key challenge-response authentication technique U1 send to U2 a challenge r1 encrypted KU1,U2

U2 report a correct response, (r1+1) U1 declares the authentication of U2 successful Similarly, U2 can authenticate U1

Billing basics Intermediate user compensation

Attaching to forwarded packet a message integrity code(MIC) calculated under its pairwise shared key with R1

R1 ascertain the user in forwarding packet for U1

Total payment (m-units per t-unit transmitted)

Payment structure

<am> : proof token <wi,t> : payment token Procedure

(1) U1R1, a1, (2) R1 checks MIC (3) saves

To use <wi+1,t> (1) U1R1, (2) R1 check (3) R1 checks MIC

Making paymentsU1 maintains a debt counter

R1 maintains a profit counter : maximum amount that user can owe : U1 make a payment

UserPayment format

(wi,j, j), where and

Micropayment (wi,j, j)

1 1U RDC

u j t

1

1 Rj u L

1 1

1U UDC DC j u L

1UDC

1UPC

1R

RouterStore payment token with highest index

(wi,k, k)

Receipt of (wi,j, j), R1 verifies j>k,

After verification, R1 replace (wi,k, k) with (wi,j, j) and

Intermediate usersR1 pay on behalf of U1

1 1U UPC PC j k L

Redemption of payment structureBroker VS R1

Payment record

Procedure

SecurityA user signs a payment structure digitallyPayment structure is both user-specific and

router-specific Low Computation

Rare public-key operationFast hash operation

Small Storage Communication

More efficient than home-foreign-domain model

UPASSFirst known secure authentication and

billing architecture for large-scale WMNsHomeless, no need for SLAsHybrid IBC/CBC trust modelLightweight realtime micropayment

approach