T' C' Yeh and S' C' Tsai

1
Securing Mobile Commerce Transactions
IEICE Transactions on Communications,
vol.E89-B, no.9, pp. 2608-2611, 2006

• T. C. Yeh and S. C. Tsai

Presented by Huei-Ru Tseng
2
Securing Mobile Commerce Transactions
IEICE Transactions on Communications,
vol.E89-B, no.9, pp. 2608-2611, 2006

• T. C. Yeh and S. C. Tsai

Presented by Huei-Ru Tseng
3
Outline
1
Introduction
2
The mobile commerce model
3
Lam et al.s Lightweight security mechanism
4
The Proposed Scheme
5
Security Analysis
4
Introduction (1/2)

• Electronic transactions conducted over the mobile
  platform are gaining popularity
• Security over the mobile platform is more
  critical due to the open nature of wireless
  networks
• It is much easier for malicious users to
  perform fraudulent activities such as
  eavesdropping and impersonation

5
Introduction (2/2)

• Security is more difficult to implement on a
  mobile platform because of the
  resource limitation of mobile handheld devices
• It is important to have some lightweight
  security mechanisms suitable for mobile
  handheld devices

6
Related Work

• Lam et al. proposed a lightweight security
  mechanism that achieved end-to-end security
  between the mobile device and the mobile
  commerce provider
• Its security builds on the assumption that the
  mobile device can confirm every mobile
  commerce providers public key before each
  transaction

7
Secure Mobile Commerce Architecture
Mobile Commerce Provider
End User
Mobile Client
WAP Gateway
Web Server
Wireless Protocol Gateway
Mobile Commerce Application
WTLS
TLS
End-to-end Security
8
The Contribution

• The authors propose an enhanced
  lightweight security mechanism to lessen the
  computation overhead on mobile devices
• The proposed scheme has the following
  features
• Mutual authentication
• End-to-end security
• Reduced memory requirement on the mobile devices
• Higher efficiency

9
Notations
10
Lam et al.s Security Mechanism
Wireless Protocol Gateway
WAP Gateway
Mobile Client
1
2
3
11
Security Processing at Wireless Protocol Gateway
Password Database
End User Device
Wireless Protocol Gateway
Trusted Connection
3. Send verification data to TR hardware
Tamper-resistant Hardware
4. Decrypt user entered PIN 5. Compute H(PIN) 6.
Compare H(PIN) and H(password) 7. Send
verification result to gateway
12
The Security Issues

• Verification of the wireless gateways
  public key
• The protocol assumes that the user has the
  wireless protocol gateways public key in advance
• However, users could hardly verify the validity
  of the public keys by themselves
• Over-loaded mobile client
• The protocol consumes lots of memory spaces and
  computation costs

13
The Proposed Scheme
Wireless Protocol Gateway
WAP Gateway
Mobile Client
1
1
2
3
14
Security Analysis (1/3)

• Mutual authentication
• The mobile client authenticates itself to the
  mobile commerce provider by PIN
• The mobile commerce provider authenticates itself
  to the mobile client by the ability to decrypt Rb
  with its private key
• End-to-end security
• The session key establishes end-to-end security
  between the mobile client and the mobile
  commerce provider

15
Security Analysis (2/3)

• Increased security
• The WAP gateway verifies the mobile commerce
  providers public key
• The storage problems of public keys on the mobile
  client are avoided
• Reduced memory requirement on the mobile
  devices
• The mobile client doesnt need to keep the
  providers public key

16
Security Analysis (3/3)

• Higher efficiency
• Only one public key encryption and one random
  number generation are needed on the mobile
  client

17
The Security Issues

• Once a password database is
  compromised, all the user PVD (password
  verification data) fall in the hands of
  attackers
• If an attacker colludes with the WAP
  gateway, the session key could be derived by the
  attacker

attack
18
The Attack Scenario
Wireless Protocol Gateway
BAD WAP Gateway
Mobile Client
1
Since the attacker have H(PIN), he can easily
derive Ra
1
2
The attacker can decrypt this ciphertext to get Rb
3
19
Conclusion

• Mobile commerce requires robust and lightweight
  security mechanisms
• The authors revise the lightweight mobile
  commerce security mechanism proposed by Lam et
  al.
• The proposed scheme is more suitable for
  security-sensitive mobile environment
• However, the scheme is suffers from
  several attacks