Efficient Scheme for Secure and Privacy-Preserving Electric Vehicle - - PowerPoint PPT Presentation

Efficient Scheme for Secure and Privacy-Preserving Electric Vehicle Dynamic Charging System

IEEE ICC 2017 Paris, France May 21 - 25, 2017 Presenter:

Outline

• I ntroduction
• Proposed Scheme
• Evaluations
• Conclusion

W hat is EV Dynam ic Charging?

• The dynamic charging technology will enable Electric Vehicles (EVs) to

charge their batteries while moving.

• Charging pads are placed on the roads to charge the EVs through the

magnetic induction.

• Dynamic charging can can help the EVs that drive for long distances.

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charging pads

Challenges:

• Security

 Authentication and secure payment

• Privacy

 No entity should know the location of the drivers

• Efficiency  Cost-effective pads have limited computational power
• Scalability  Large number of EVs and Pads.
• Short contact tim e between the EVs and pads

Problem Form ulation

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To propose a scheme which can address all these challenges.

Our Objective

• The dynamic charging system should communicate with the EVs to only

charge authorized vehicles and ensure payment integrity.

Outline

• Introduction
• Proposed Schem e
• Evaluations
• Conclusion

Netw ork Model

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Exchanged Messages

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1 . Anonym ous Coin Purchase

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IDi  identity of the User TS  Time stamp be (gx)  blinded coin PBS(be (gx), date)  Partial Blind Signature on coin gx, date, sigB(gx, date)  Un-blinded Anonymous Coin

2 . Charging Request and paym ent

gx gy, Ek(gy, gx), 𝜏C Ek(gy, gx, date, SigB(gx, date)) Ek1(gx, date, SigB(gx, date)) Valid/Invalid Coin Ek(Seed token)

EVi CSP Bank

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Steps 1 -3 : Key Establishment and Authentication Steps 4 -5 : Coin Verification Step 6 : Sending Token

3 . Efficient Hierarchical Authentication

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• EV should authenticate itself first to the CSP and then to RSU and

then to charging pads.

• In each level, the EV uses the secrets obtained from the previous

level.

1 . Efficient Key Generation and Distribution:

𝜷1,1 𝜷1,2 𝜷1,nr-1 𝜷1,nr

H( )

𝜷n,nr

RSU2 EV1 Hk( ) RSU1

H( )

RSUnr

𝜷2,1 𝜷2,2 𝜷2,nr-1 𝜷2,nr

H( )

EV2

H( )

𝜷n-1,1 𝜷n-1,2 𝜷n-1,nr-1 𝜷n-1,nr

EVn-1

Hk( )

𝜷n,1 𝜷n,2 𝜷n,nr-1

H( )

EVn

H( ) H( )

𝜸n,nr 𝜸1,2 𝜸1,nr-1 𝜸1,nr

H( )

RSU2 EV1 Hk( ) RSU1

H( )

RSUnr

𝜸2,1 𝜸2,2 𝜸2,nr-1 𝜸2,nr

H( )

EV2

H( )

𝜸n-1,1 𝜸n-1,2 𝜸n-1,nr-1 𝜸n-1,nr

EVn-1

𝜸n,1 𝜸n,2 𝜸n,nr-1

H( )

EVn

H( ) H( )

𝜸1,1

Hk( ) Hk( )

H( )

Token Generation matrix-1 b/w CSP & RSUs Token Generation matrix-2 b/w CSP & RSUs

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• CSP shares a group secret key with all RSUs.
• This key is used to distribute the seeds 𝛽n,nr and β1,1

for generating two token matrices.

𝜸1,j 𝜷1,j

⊕

𝜷1,j ⊕ 𝜸1,j 𝜸2,j 𝜷2,j 𝜷2,j ⊕ 𝜸2,j 𝜸n-1,j 𝜷n-1,j 𝜷n-1,j ⊕ 𝜸n-1,j 𝜸n,j 𝜷n,j 𝜷n,j ⊕ 𝜸n,j

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Calculation of shared keys by RSUs:

• After computing its two sets of tokens, each RSU should compute the

shared keys with the CSP by XORing corresponding two elements in the columns.

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Calculation of shared keys betw een EV and RSU by an EV:

• When an EV authenticates itself to the CSP, it received two seed tokens

(βi,1 and 𝛽i,nr) in the last step of charging request.

• EV uses 𝛽i,nr as seed for one hash chain

βi,1 as seed for another hash chain

• XORing corresponding two elements in two hash chains will give the

shared keys.

i,10

H( )

i,5 i,6 i,10

H( )

i,5 i,6 i,7

H( )

i,6

H( )

Partial Charging:

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• One coin can be enough to charge from a certain number of pads.
• Our scheme can be used to limit the number of RSUs’ pads an EV can

charge from by limiting the number of keys the EV can calculate.

2 . Authentication at RSU and CP

EVi RSUj Challenge: ri Ack: H (αi,j ⊕ βi,j || ri || 1) Response: H (αi,j ⊕ βi,j || ri)

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• Challenge/response authentication to prove the knowledge of secret

keys.

• If the EV is authenticated by RSU, it sends a token to EV which will

be used to compute the shared keys with the pads.

• We use the same idea to authenticate EV at RSUs’ charging pads.

Outline

• Introduction
• Proposed Scheme
• Evaluations
• Conclusion

• In order to evaluate the computation overhead, we used Crypto++

5.6.2 library to measure the computation time of the cryptographic

• perations used in our scheme.
• In our measurements, we used a 900MHz speed processor.

Entities Storage Overhead Computation Overhead E.V (nr 20) + (np 20) bytes 0.167 𝝂sec + 0.125 𝝂sec Charging Pads n 20 bytes (n -1) (np -1) 0.0418𝝂sec + 0.0418 𝝂sec RSU n 20 bytes 2 (n -1) (nr -1) 0.0418𝝂sec + 0.23 𝝂sec + 0.0418 𝝂sec CSP 2 n 20 bytes 2 (n -1) (nr -1) 0.0418𝝂sec + 0.23 𝝂sec

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Evaluations

Outline

• Introduction
• Proposed Scheme
• Evaluations
• Conclusion

• In this paper, we have proposed an efficient secure and privacy

preserving scheme for Dynamic Charging System.

• Proposed scheme can secure the prepaid payment while offering full

anonymity to EV drivers.

• Proposed an efficient technique to compute and share a large number
• f secret keys.
• Developed an efficient hierarchical authentication scheme that uses

efficient cryptosystems like hashing and Exclusive-OR operations.

• Our measurements have demonstrated that the proposed scheme is

efficient and scalable.

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Questions