1. 無線通訊的安全技術及電子商務應用之研究
Security Technologies on Wireless Communications and Applications in Electronic Commerce
指導教授: 張真誠 教授
研究生: 李榮三
Dept. of Computer Science and Information Engineering, National Chung Cheng University

2. Outline Part 1: Security Technologies for Wireless Communications
Part 2: Applications to Electronic Business
MSN lab

3. Introduction Authentication & Data Integrity Electronic Commerce
Global system for mobile communications (GSM)
Anonymous authentication mechanism
Secure Communications for Ad Hoc Networks
Electronic Commerce
Electronic voting
Oblivious transfer
MSN lab

4. Efficient Authentication Protocols for GSM
LAI1
LAI2
LAI3
LAI4
LAI5
LAI6
VLR
HLR
MSN lab

5. Current GSM authentication system
HLR: The home location register
VLR: The visitor location register
IMSI: The international mobile subscriber module
TMSI: The temporary mobile subscriber identity
K: The secret key shared between MS and HLR
A3( )/A8( ), A5( ): two one-way functions, en/decryption function
MSN lab

6. Current GSM authentication system(1/2)MS
VLR
HLR
Request (TMSI, LAI)
SRES=A3(R, K)
IMSI
Kc=A8(R, K)
n sets {SRES,R,Kc}
SRES’=A3(R, K)
TMSI’, R
Kc=A8(R, K)
SRES’
SRES= SRES’
MSN lab

7. Current GSM authentication system(2/2)MS
VLR
Request (TMSI’)
SRES,R,Kc R
SRES’=A3(R, K)
SRES= SRES’
SRES’
Kc=A8(R, K)
MSN lab

8. Drawbacks Unilateral authentication between VLR and MS
Storage overhead
Bandwidth consumption
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9. Protocol 1 (Phase 1) MSN lab CERT_VLR=A3(R,K) CERT_VLR’=A3(R,K)
HLR
Request (TMSI ,LAI,T)
CERT_VLR=A3(R,K)
IMSI, T
CERT_VLR’=A3(R,K)
Kc=A8(R, K)
Kc=A8(R, K)
CERT_VLR, R, Kc
TMSI’, CERT_VLR, R, R1, T
SRES’=A5(R1, Kc)
SRES=A5(R1, Kc)
SRES’
MSN lab

10. Protocol 1 (Phase 2) MSN lab CERT_VLR’j =A3(Tj,Kc) CERT_VLRj=A3(Tj,Kc)
Request (TMSI’, Tj)
CERT_VLR’j =A3(Tj,Kc)
CERT_VLRj=A3(Tj,Kc)
CERT_VLRj, Rj, Tj
SRES’j=A5(Rj, Kc)
SRESj=A5(Rj, Kc)
SRESj’
MSN lab

11. Protocol 2 (Phase 1) MSN lab CERT_VLR=A3(T, K) CERT_VLR’=A3(T, K)
HLR
Request (TMSI ,LAI,T)
CERT_VLR=A3(T, K)
IMSI, T
CERT_VLR’=A3(T, K)
Kc=A8(R, K)
Kc=A8(R, K)
CERT_VLR, R, Kc
TMSI’, CERT_VLR, R, T
SRES’=A5(R||T, Kc)
SRES=A5(R||T, Kc)
SRES’ T
TMSI’, T
MSN lab

12. Request (TMSI’, SRESj, Tj)
Protocol 2 (Phase 2) MS
VLR
SRES’j=A5(Tj||Tj-1, Kc)
Request (TMSI’, SRESj, Tj)
SRES’j=A5(Tj||Tj-1, Kc)
CERT_VLR’j =A3(Tj,Kc)
CERT_VLRj, Rj, Tj
CERT_VLRj=A3(Tj,Kc) Tj
TMSI’, Tj
MSN lab

13. Analyses Mutual Authentication Reduce storage overhead
Avoid bandwidth consumption
Round efficiency (Protocol 2)
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14. Comparisons between current GSM authentication protocols and ours
Original
[14]
[15]
[49]
[51]
Ours
MA1 No
Yes
MA2
SSO
SBC AC -
MSN lab

15. Anonymous Authentication Scheme for Wireless Communications
To enhance the privacy of mobile subscriber
Foreign Agent (FA)->VLR
Home Agent (HA)->HLR
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16. The flowchart of Zhu and Ma’s schemeMS FA HA
n, EKL(r0), IDHA, TMS
R1, n, EKL(r0), TMS, SIGFA, CertFA, TFA
R2, [h(IDMU) || r0] KUFA,SIGHA,
CertHA, THA
EK(TCertMS)
The flowchart of Zhu and Ma’s scheme
MSN lab

17. The flowchart of our scheme
C1 = h(h(X)  r)  IDi MS FA HA
IDHA, C1, r, EKMH(h(C1⊕T1) || N1 || T1)
IDFA, EKFH(EKMH(h(C1⊕T1) || N1 || T1) || C1 || r || N2 || T2)
ESK(h(N1) || TIDi), EKMH(h(N2) || T1+1)
EKFH(h(N1) || T2+1), EKMH(h(N2) || T1+1)
SK = h(h(N1)  h(N2))
The flowchart of our scheme
MSN lab

18. Comparisons between related works and ours
154%
1.06%
1.45%
[42]
[43]
Ours MS FA HA NA
1/2
2/1
1/1 NE 4 2 NS
1/0
0/1
2/2 NH 5 NO 3 1
MSN lab

19. Secure Communications for Cluster-based Ad Hoc Networks Using Node Identities
nodes
Clusterhead
Radio range
The structure of NTDR
MSN lab

20. Trust Authority (TA) ed  1 (mod ψ(N))
MIDi, Ki = e(logg(MIDi2)) modψ(N)
CHIDj, CKj = e(logg(CHIDj2)) modψ(N)
AUC=h(KMH)
MSN lab

21. The authentication flowchart of our scheme
MIDi
CHIDj
CHIDj, CIDj
MIDi, AUC, T
The authentication flowchart of our scheme
MSN lab

22. The communicating nodes are within one hop
clusterhead CHIDj
CIDj
nodes
MID2
within one hop
Limit of beacon messages
MID1
The communicating nodes are within one hop
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23. The communicating process of Case 1
Cert=h(K12)
MID1
MID2
MID1, T1, Cert
The communicating process of Case 1
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24. The communicating nodes are not within one hop
CIDj
clusterhead CHIDj
nodes
within one hop
limit of beacon messages
MID1
MID2
The communicating nodes are not within one hop
MSN lab

25. MSN lab

26. The communicating nodes are not within the same cluster
CID1
CID2
CHID2
CHID1
MID1
MID2
The communicating nodes are not within the same cluster
MSN lab

27. MSN lab

28. Authentication Data-integrity Non-repudiation Non-impersonation
Mobile nodes in the same cluster
Mobile nodes are in different clusters
Non-repudiation
Non-impersonation
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29. Performance comparisons of authentication phase
Role
Scheme
[76]
Ours
MIDi
3 PKI
1 exp + 2 sym + 2 h
CHIDj
MSN lab

30. Performance comparisons of communication phase
(Nodes in the same cluster)
Role
Scheme
[76]
Ours
MID1
8 sym + 1h
2 sym + 1h
CHID1
8 sym
4 sym
MID2
MSN lab

31. Performance comparisons of communication phase
(Nodes in different clusters)
Role
Scheme
[76]
Ours
MID1
8 sym + 1h
2 sym + 1h
CHID1
8 sym
4 sym
CHID2
MID2
4 sym + 1h
MSN lab

32. An Anonymous Voting Mechanism Based on the Key Exchange Protocol
Previous works: PKI
Blind signature
Diffie-Hellman key exchange protocol
MSN lab

33. Blind signature Signer: ed  1 (mod ψ(N))
Client: message m, random number r
m' = mre mod N
Signer: s' = (m')d =mdr mod N
Client: s = s'r-1 mod N
=((mre)d)r-1 N
= md mod n
MSN lab

34. Diffie-Hellman key exchange protocol
ga mod p
Bob
Alice
gb mod p
gab mod p
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35. Variant version yb=gxb mod p ya=gxa mod p gxaxb mod p ybxa mod p
Bob
Alice
yb=gxb mod p
ya=gxa mod p
yaxb mod p
gxaxb mod p
MSN lab

36. Requirements Anonymity
Fairness: no one can learn the temporary outcome
Convenience
Robustness:
Mobility
Uniqueness
Completeness: only the eligible voter is allowed to vote
Uncoercibility: each voter must be able to decide his intention
Correctness
Efficiency：within a reasonable period of time
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37. The whole structure of our proposed mechanism
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38. Comparisons between our scheme and other related works
Requirement
Scheme
Ours
[27]
[3]
[30]
Anonymity
Yes
Fairness No
Convenience
High
Low
No mention
Mid
Robustness
Mobility
Uniqueness
Completeness
Uncoercibility
Correctness
Efficiency
MSN lab

39. Choosing t-out-of-n Secrets by Oblivious Transfer
Request t messages
messages
Bob
Alice
1. Correctness
Stocks
2. Privacy of Bob
Message query
3. Privacy of Alice
MSN lab

40. Chinese Remainder Theorem (CRT)
To find a positive integer C that satisfies the following congruence,
C ≡ 2 (mod 3),
C ≡ 3 (mod 5), and
C ≡ 3 (mod 7).
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41. Define Notations N: a large prime
e/d: the public/private key of Alice,
a1, a2, …, an: n messages
d1, d2, …, dn: n relatively prime numbers
IDi: the identity of message ai
b1, b2, …, bt: t messages that Bob expected to get
MSN lab

42. Alice Step 1: Computes D = d1* d2* …* dn,
and constructs congruence system as,
C ≡ a1 (mod d1),
C ≡ a2 (mod d2),
C ≡ an (mod dn).
C = (D/d1)y1a1 + (D/d2)y2a2 + … + (D/dn)ynan mod D by CRT,
where (D/di)yi ≡ 1 (mod di)
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43. Alice Step 2: Computes T1 = d1e mod N, T2 = d2e mod N, Tn = dne mod N,
Step 3: Publish
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44. Alice Bob Request C (ID1, T1) (ID2, T2) (IDn, Tn) C and n pairs
C and t pairs
{1, 2, …, t}
{β1, β2, …, βt}
board
MSN lab

45. Bob Step 1:(IDj, Tj), for j = 1, 2 to t Step 2:
1 = r1e * T1 mod N,
2 = r2e * T2 mod N,
t = rte * Tt mod N,
Step 3: Sends {1, 2, …, t} to Alice
MSN lab

46. Alice Step 1: β1 = 1d = r1ed * T1d = r1 * T1d mod N,
βt = td= rted * Ttd = rt * Ttd mod N,
Step 2: Sends {β1,β2, …, βt} to Bob
MSN lab

47. Bob Step 1: d1 = r1-1 *β1 = T1d = d1 ed mod N,
dt = rt-1 *βt = Ttd = dt ed mod N.
Step 2:
b1 = C mod d1,
b2 = C mod d2,
bt = C mod dt.
MSN lab

48. Comparisons Alice Bob Naor and Pinkas’s (t times) 4(t*n) exp 4t exp
Wakaha and Ryota’s
4n exp
(3t + 1) exp
Ours
n+t exp
t exp
MSN lab

49. Conclusions and Future Works
Authentication
GSM
Ad hoc networks
3G,…
Electronic commerce
Electronic voting
Oblivious transfer
Electronic lottery
MSN lab

50. 無線通訊的安全技術及電子商務應用之研究
Security Technologies on Wireless Communications and Applications in Electronic Commerce
Thanks!