Security analysis and improvement of a user-friendly remote authentication protocol

doi:10.1016/j.amc.2004.06.144

Applied Mathematics and Computation

Volume 168, Issue 1, 1 September 2005, Pages 47-50

https://doi.org/10.1016/j.amc.2004.06.144 Get rights and content

Abstract

Remote user authentication is very important in a distributed computer environment. Recently Wu and Chieu devised a user-friendly remote authentication protocol using smart card. This article shows that their protocol is vulnerable to the forged login attack. Then a simple improvement is suggested to eliminate the vulnerability.

Introduction

In a distributed computer environment, when a user requests a server’s service, he must pass an examination of user authentication. Due to the portability and cryptographic capacity, smart cards have been widely used in many e-commerce applications. In 2003 Wu and Chieu [1] devised a user-friendly remote authentication protocol using smart card to improve Sun’s scheme [2] to be user-friendly that is, users can freely choose and change their passwords. Wu and Chieu claim that their protocol is efficient and secure. However, in the paper we demonstrate that the attacker can mount a forged login attack successfully on their protocol. Also a simple improvement is suggested to eliminate the weakness.

The paper is organized as follows. In Section 2, Wu–Chieu protocol is reviewed. In Section 3 we propose a forge login attack on the protocol. Then in Section 4 a simple improvement is suggested to enhance the security in Section 3. In Section 5 we analyze the security of our improved protocol. Conclusions are presented in Section 6.

Section snippets

Review of Wu–Chieu protocol

Like other remote authentication protocols using smart card, Wu–Chieu protocol [1] is separated into three phases, namely, the registration, login and authentication phases.

Cryptanalysis of Wu–Chieu protocol

A forged login attack can be constructed as follows.

Assume an intruder can get the identifier IDi of a legal user Ui by some way, e.g. intercepting the login message {IDi, Bi*, C1, T} sent by Ui. The intruder can easily forge a login message of Ui as follows after choosing a timestamp T′.

1.
He randomly chooses a number Bi′ and computes C1′ = h(T′ ⊕ Bi′).
2.
Then he sends the forged login message {IDi, Bi′, C1′, T′} to the remote system.

Upon receiving {IDi, Bi′, C1′, T′}, according to Wu–Chieu protocol, the system

Improvement of Wu–Chieu protocol

It can be seen that success of the above forged login attack depends on that the values of Bi*, C1, T used in the verification equation in Wu–Chieu protocol can be forged. The attacker can always forge a triple of values (Bi′, C1′, T′) for (Bi*, C1, T), which satisfies C1′ = h(T′ ⊕ Bi′), and thereby pass the authentication of the system. To fix this flaw we modify Wu–Chieu protocol as follows.

In the registration phase, operations and computations are kept same as in Wu–Chieu protocol.

In the login

Security analysis of our improved protocol

First, in our improved version C1 is computed as C1 = h(T, Bi, Ai), and the value of Ai is only known to the smart card and the remote server. Moreover, due to one-way hash function it is computationally infeasible for the attacker to compute Ai given the intercepted values of Bi*, C1, T sent by Ui, where Bi* = Bi. Therefore, unlike in the original Wu–Chieu protocol, the attacker cannot forge a valid value of C1 to pass the authentication of the system in the improved protocol. As an example,

Conclusion

In the paper we show Wu–Chieu protocol is vulnerable to the forged login attack. Then a simple improvement is suggested to eliminate the vulnerability. Our improvement eliminates the security flaw in Wu–Chieu protocol while meets Wu–Chieu’s original requirement of user friendliness.

References (2)

S.T. Wu et al.
A user-friendly remote authentication scheme with smart cards
Computer and Security
(2003)
H.M. Sun
An efficient remote use authentication scheme using smart card
IEEE Transaction on Consumer Electronics
(2000)

Cited by (4)

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Citation Excerpt :
represents an insecure channel For a self-contained discussion, we review the remote authentication scheme proposed by Wang et al. [3]. Their scheme consists of three phases: the registration phase, the login phase, and the authentication phase.
In an open network environment, the remote authentication scheme using smart cards is a very practical solution to validate the legitimacy of a remote user. In 2003, Wu and Chieu presented a user-friendly remote authentication scheme using smart cards. Recently, Wang, Li, and Tie found that Wu–Chieu’s scheme is vulnerable to the forged login attack, and then presented an improvement to eliminate this vulnerability. In our opinion, the smart card plays an important role in those schemes. Therefore, we demonstrate that Wang–Li–Tie’s scheme is not secure under the smart card loss assumption. If an adversary obtains a legal user’s smart card even without the user’s corresponding password, he can easily use it to impersonate the user to pass the server’s authentication. We further propose an improved scheme to overcome this abuse of the smart card.
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2007, SECRYPT 2007 - International Conference on Security and Cryptography, Proceedings
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2007, Proceedings of The 2007 International Conference on Security and Management, SAM'07

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