Secure Authentication Scheme with Anonymity for Wireless Communications

Speaker : Hong-Ji Wei

Date : 2012-12-08

2

Outline

1. Introduction

2. Review of Wu et al.’s scheme

3. Weakness of Wu et al.’s scheme

4. Improved Scheme

5. Security Analysis

6. Conclusion

3

1. Introduction

In recent years, many authors proposed the anonymous authentication scheme for wireless communications.

In 2004, Zhu and Ma proposed an authentication scheme with anonymity for wireless communications. However, in 2006, Lee, Hwang and Laio pointed out that Zhu-Ma’s scheme exists some weaknesses and proposed the improved scheme to overcome these weaknesses in Zhu-Ma’s scheme.

4

1. Introduction

In 2008, Wu, Lee and Tsaur pointed out that Lee et al’s scheme still exists weakness of anonymity and backward secrecy. Therefore, they also proposed an improved scheme to improve the weaknesses in Lee et al.’s scheme.

In 2009, Zeng et al and Lee et al found out that Wu et al.’s scheme still not protect the anonymity of user. However, they did not propose the scheme to improve it.

5

1. Introduction

In 2009, Chang et al. also pointed out that Wu et al’s scheme exists two weaknesses, which failed to achieve the anonymity and prevent impersonation attack. At the same time, they also proposed the improved scheme to overcome these weaknesses. However, it’s unfortunately, their proposed scheme still not efficiently overcome these weaknesses.

In this paper, we will analyze Wu et al.’s scheme and propose a secure anonymous authentication scheme to improve the security weaknesses in Wu at al.’s scheme.

6

2. Review of Wu et al.’s scheme

Notations

MU : Mobile User

HA : Home Agent of a mobile user

FA : Foreign Agent of the network

IDA: Identity of A

TA : Timestamp of A

CertA : Certificate of A

(X)K : Symmetric Encryption

EK(X) : Asymmetric Encryption

h(X) : Hash X using hash function

PWA : Password of A

PA : Public key of A

SA : Private key of A

7

2. Review of Wu et al.’s scheme This scheme can be divided into three phases

1. Initial Phase

MU registers with HA through secure channel.

2. First Phase

FA authenticates MU through HA and establishes a session

key with MU.

3. Second Phase

MU updates the session key with FA.

8

2. Review of Wu et al.’s scheme Initial Phase

MU HA

Secure Channel

Secure ChannelMUIDMUID

MUHA

MUHA

MUMU

IDID

ID||NhID||Nhr

ID||NhPW

)()(

)(

h(.),IDr,,PW HAMU

9

2. Review of Wu et al.’s scheme First Phase

MU FA HA

MU

MUMU

PWrn

PWThL

Compute 1.

)(

MUHAL0MU TID,x||x||IDhn, 2. ,))((

FA

MU

S with signatureCompute

bnumber random Generate

T Check 3.

),,))((((

,,))((

FAMUL0MUS

FAFAMUL0MU

CertTx||x||IDhn,b,hE

CertTT,x||x||IDhn,b, 4.

FA

))))||(((

?)()'(

with))((

'

0MUP

HA

MUMU

0MU

MUHAHA

FAFA

x||x||IDNhhEW Compute

S with signatureCompute

cnumber random Generate

IDhIDh Check

L x||x||IDh Decrypt

IDIDn)ID||h(N Compute

T and Cert Check 5.

FA

HAHAHAPS TCert,CertWhEc,b,hEW,c, 6.FAHA

,),)))((((

)))||(((

.6

0MU

FA

x||x||IDNhhh k

key sessionCompute

S withW Decrypt

k0MU x||xhTCert ))(||(.7

k withx||xhTCert Decrypt

k Compute

0MU ))(||(

.8

kMU1 ationOtherInfom||TCert||x )(.9

10

2. Review of Wu et al.’s scheme Second Phase

In order to enhance the efficiency, while MU stays with the same FA, the new session key ki can be derived from the unexpired previous secret knowledge xi−1 and a fixed secret x as

MU FA

Session key update

1,2,3...nifor x||x||IDNhhh k 1-iMUi )))||(((

ikMUiMU ationOtherInfom||TCert||xTCert )(,

3. Weakness of Wu et al.’s scheme Anonymity

MUHAMUHA IDIDID||NhrID||Nh 1. )()(

HAHAMU IDID||NhnID 2. )(

Attacker

MU FA HA

MU

MUMU

PWrn

PWThL

Compute 1.

)(

MUHAL0MU TID,x||x||IDhn, 2. ,))((

FA

MU

S with signatureCompute

bnumber random Generate

T Check 3.

),,))((((

,,))((

FAMUL0MUS

FAFAMUL0MU

CertTx||x||IDhn,b,hE

CertTT,x||x||IDhn,b, 4.

FA

))))||(((

?)()'(

with))((

'

0MUP

HA

MUMU

0MU

MUHAHA

FAFA

x||x||IDNhhEW Compute

S with signatureCompute

cnumber random Generate

IDhIDh Check

L x||x||IDh Decrypt

IDIDn)ID||h(N Compute

T and Cert Check 5.

FA

HAHAHAPS TCert,CertWhEc,b,hEW,c, 6.FAHA

,),)))((((

)))||(((

.6

0MU

FA

x||x||IDNhhh k

key sessionCompute

S withW Decrypt

k0MU x||xhTCert ))(||(.7

k withx||xhTCert Decrypt

k Compute

0MU ))(||(

.8

kMU1 ationOtherInfom||TCert||x )(.9

11

12

3. Weakness of Wu et al.’s scheme Impersonation attack

*PWIDIDID||NhnID||Nh 2.

*PWIDIDID||NhID||Nh

*PWr 1.n

MUHAHAMU

MUHAMUHA

)()(

)()(

MU FA HA

MU

MUMU

PWrn

PWThL

Compute 1.

)(

MUHAL0MU TID,x||x||IDhn, 2. ,))((

FA

MU

S with signatureCompute

bnumber random Generate

T Check 3.

),,))((((

,,))((

FAMUL0MUS

FAFAMUL0MU

CertTx||x||IDhn,b,hE

CertTT,x||x||IDhn,b, 4.

FA

))))||(((

?)()'(

with))((

'

0MUP

HA

MUMU

0MU

MUHAHA

FAFA

x||x||IDNhhEW Compute

S with signatureCompute

cnumber random Generate

IDhIDh Check

L x||x||IDh Decrypt

IDIDn)ID||h(N Compute

T and Cert Check 5.

FA

HAHAHAPS TCert,CertWhEc,b,hEW,c, 6.FAHA

,),)))((((

)))||(((

.6

0MU

FA

x||x||IDNhhh k

key sessionCompute

S withW Decrypt

k0MU x||xhTCert ))(||(.7

k withx||xhTCert Decrypt

k Compute

0MU ))(||(

.8

kMU1 ationOtherInfom||TCert||x )(.9

PWMU *

Attacker

13

4. Improved scheme Registration Phase

MU HA

Secure Channel

Secure ChannelMUID MIDMU ,

)||)((

)(

)(

NMIDhhL

M

IDIDID||Nhn

ID||MhPW

MU

MUHAHA

MUMU

Lh(.),,IDn,,PW HAMU

14

Authentication and establishment session key phase

4. Improved scheme

MUMUHAL0MU TID,x||x||MIDhn, ,))((.2

FA

MU

S withe signaturCompute

bnumber random Generate

T Check .3

)),,))((((

,,))((.4

FAMUL0MUS

FAFAMUL0MU

CertTx||x||MIDhn,b,hE

CertTT,x||x||MIDhn,b,

FA

)))(((

?)()'(

with))((

'

.5

0MUP

HA

MUMU

0MU

MUHAHA

FAFA

x||x||MIDhhEW Compute

S withe signaturCompute

cnumber random Generate

MIDhM'IDh Check

L x||x||MIDh Decrypt

M'IDIDn)ID||h(N Compute

T and Cert Check

FA

HAHAHAPS TCert,CertWhEc,b,hEW,c, .FAHA

,),)))((((6

)))(((

.7

0MU

FA

x||x||MIDhhh k

key sessionCompute

S withW Decrypt

k0MU xhTCert ))(||(.8

)(with)(

))(||(

.9

00

0MU

xh 'xh Compare

k withxhTCert Decrypt

k Compute

kMU1 ationOtherInfom||TCert||x )(.10

FA HA

L withx||x||MIDh Encrypt

?PW'PW Check

ID||M''PW Compute

M'Enter

0MU

MUMU

MUMU

))((

)(

.1

15

4. Improved scheme Session key update phase

In order to enhance the efficiency, while MU stays with the same FA, the new session key ki can be derived from the unexpired previous secret knowledge xi−1 and a fixed secret x as

MU FA

Session key update

, ( )iMU i MU kTCert x TCert OtherInfomation

1,2,3...nifor x||x||MIDhhh k 1-iMUi )))(((

16

Password change phase

MU FA HA

MUHAL1MU TID,M||M||MIDhn, . ,))((2 FA

MU

S withe signaturCompute

bnumber random Generate

T Check .3

)),,))((((

,,))((.4

FAMUL1MUS

FAFAMUL1MU

CertTM||M||MIDhn,b,hE

CertTT,M||M||MIDhn,b,

FA

HA

Snewnewnew

MU

1MU

1MUHAHAnew

1MUnew

1MUnew

MU

MUMU

MUMU

0MU

MUHAHA

FAFA

S withe signaturCompute

cnumber random Generate

n||L||PWW Compute

MMIDh SCompute

MIDIDIDNhn Compute

NMIDh(hL Compute

MIDhPW Compute

MM'IDID Compute

MIDhM'IDh Check

L x||x||MIDh Decrypt

M'IDIDn)ID||h(N Compute

T and Cert Check

)(

)||||(

)||(

)||)(

)(

'

?)()'(

with))((

'

.5

HAHAHAPS TCert,CertWhEc,b,hEW,c, FAHA

,),)))((((.6

FA

HAHA

S withe signaturCompute

Cert and T Check .7

card smartinto n LPW Store

S withW Decrypt

M)||M||(ID SCompute

Cert and T Check

newnewnewMU

1MU

FAFA

and

.9

、

4. Improved scheme

L withM||M||MIDh Encrypt

Mnumber random new Generate .

1MU

1

))((

1

FAFAFAS CertT,CertWhEW, FA

,),)((.8

17

5. Security Analysis Anonymity

MUHAHA IDIDrID||Nh 1. )(

HAHAMU IDID||NhnMID 2. )(

Attacker

MUMUHAL0MU TID,x||x||MIDhn, ,))((.2

FA

MU

S withe signaturCompute

bnumber random Generate

T Check .3

)),,))((((

,,))((.4

FAMUL0MUS

FAFAMUL0MU

CertTx||x||MIDhn,b,hE

CertTT,x||x||MIDhn,b,

FA

)))(((

?)()'(

with))((

'

.5

0MUP

HA

MUMU

0MU

MUHAHA

FAFA

x||x||MIDhhEW Compute

S withe signaturCompute

cnumber random Generate

MIDhM'IDh Check

L x||x||MIDh Decrypt

M'IDIDn)ID||h(N Compute

T and Cert Check

FA

HAHAHAPS TCert,CertWhEc,b,hEW,c, .FAHA

,),)))((((6

)))(((

.7

0MU

FA

x||x||MIDhhh k

key sessionCompute

S withW Decrypt

k0MU xhTCert ))(||(.8

)(with)(

))(||(

.9

00

0MU

xh 'xh Compare

k withxhTCert Decrypt

k Compute

kMU1 ationOtherInfom||TCert||x )(.10

FA HA

L withx||x||MIDh Encrypt

?PW'PW Check

ID||M''PW Compute

M'Enter

0MU

MUMU

MUMU

))((

)(

.1

18

5. Security Analysis Impersonation Attack

MUMUHAL0MU TID,x||x||MIDhn, ,))((.2

FA

MU

S withe signaturCompute

bnumber random Generate

T Check .3

)),,))((((

,,))((.4

FAMUL0MUS

FAFAMUL0MU

CertTx||x||MIDhn,b,hE

CertTT,x||x||MIDhn,b,

FA

)))(((

?)()'(

with))((

'

.5

0MUP

HA

MUMU

0MU

MUHAHA

FAFA

x||x||MIDhhEW Compute

S withe signaturCompute

cnumber random Generate

MIDhM'IDh Check

L x||x||MIDh Decrypt

M'IDIDn)ID||h(N Compute

T and Cert Check

FA

HAHAHAPS TCert,CertWhEc,b,hEW,c, .FAHA

,),)))((((6

)))(((

.7

0MU

FA

x||x||MIDhhh k

key sessionCompute

S withW Decrypt

k0MU xhTCert ))(||(.8

)(with)(

))(||(

.9

00

0MU

xh 'xh Compare

k withxhTCert Decrypt

k Compute

kMU1 ationOtherInfom||TCert||x )(.10

FA HA

L withx||x||MIDh Encrypt

?PW'PW Check

ID||M''PW Compute

M'Enter

0MU

MUMU

MUMU

))((

)(

.1

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5. Security Analysis Comparison Table

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6. Conclusion

In this paper, we propose the secure anonymous auth-entication scheme which not only improves the above mentioned weaknesses in Wu et al.’s scheme, but also provides the extra function of changing password for mobile users.

From our security analysis, we find out that our proposed scheme indeed can improve all of the weaknesses in Wu et al.’s scheme and also achieve our expected efficiency.

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Many thanks for your listening