A user friendly remote authentication scheme with smart cards

1
A user friendly remote authentication scheme with
smart cards

• Shyi-Tsong Wu and Bin-Chang Chieu
• Computers Security,
• Vol. 22, No. 6, Sep. 2003, pp. 547-550
• Reporter Chia-Yin Lee

2
Outline

• Introduction
• Review of Suns scheme
• Wu-Chieu scheme
• Cryptanalysis of Wu-Chieu scheme
• How to overcome the weakness of Wu-Chieu Scheme
• Conclusions

3
Introduction

• Based on Suns scheme, Wu and Chieu proposed a
  user friendly remote authentication scheme.
• By using one-way hash functions and smart cards,
  Wu-Chieu scheme provides users to choose and
  change passwords freely.
• However, Wu-Chieu suffers from the forgery attack.

4
Review of Suns scheme (1/3)

• Registration phase

5
Review of Suns scheme (2/3)

• Login phase

6
Review of Suns scheme (3/3)

• Authentication phase

7
Wu-Chieu Scheme (1/4)

• Some notations

8
Wu-Chieu Scheme (2/4)

• Registration phase

9
Wu-Chieu Scheme (3/4)

• Login phase

10
Wu-Chieu Scheme (4/4)

• Authentication phase

11
Cryptanalysis of Wu-Chieu scheme (1/3)

• In 2004, Yang and Wang have presented the
  possible attacks on Wu-Chieu scheme.
• Wu-Chieu scheme suffers from password guessing
  attack and the forgery attack.

12
Cryptanalysis of Wu-Chieu scheme (2/3)

• The forgery attack
• The attacker intercepts the correct login message
• The attacker uses the correct timestamp to
  compute
• The attacker sends the login message
• to the server.

13
Cryptanalysis of Wu-Chieu scheme (3/3)

1. The attacker will pass the verify steps

14
How to overcome the weakness (1/3)

• We modified the login phase and the
  authentication phase of Wu-Chieu scheme as
  following

15
How to overcome the weakness (2/3)

• Login phase

16
How to overcome the weakness (3/3)

• Authentication phase

17
Conclusions

• Wu-Chieu scheme provides users to choose and
  change their passwords freely.
• However, it suffers from the forgery attack.
• We presented a method to overcome the existing
  weakness of the original scheme.