Informatica

Recently, Yang et al. proposed an improvement to Tseng et al.’s protected password changing scheme that can withstand denial of service attack. However, the improved scheme is still susceptible to stolen-verifier attack and denial of service attack. Accordingly, the current paper demonstrates the vulnerability of Yang et al.’s scheme to two simple attacks and presents an improved protected password change scheme to resolve such problems. In contrast to Yang et al.’s protected password changing scheme and the existing password change schemes using server’s public key, the proposed scheme can securely update user passwords without a complicated process and server’s public key.

In this paper, we propose a mutual authentication scheme using nonce variable instead of Mac address and accompanying with token updates to improve the functionality. Lee et al. (2005a) and Shi et al. (2006) proposed the site authentication schemes by using the generating random numbers. The site authentication can identify a personal computer using LAN card's Mac address, but the Mac address is easily detected through Address Resolution Protocol in the Open Systems Interconnection model. Therefore, we propose an improved securer and efficient nonce-based authentication scheme providing mutual authentication to resist the replay attack, man-in-the-middle attack and Mac address attack.

With rapid growth of mobile wireless networks, handheld devices are popularly used by people and many mobile applications have been rapidly developed. Considering the limited computing capability of smart cards or mobile devices, the security scheme design suitable for these mobile devices is a nontrivial challenge. A user authentication scheme is a mechanism to authenticate a remote user over an open network. In 2006, Das et al. proposed an identity (ID)-based remote user authentication scheme with smart cards using bilinear pairings. Unfortunately, their scheme is insecure against forgery attack. Recently, Giri and Srivastava proposed an improved scheme to overcome the forgery attack. The computational cost required by the Giri–Srivastava scheme is expensive, especially for smart cards with limited computing capability. In addition, the Giri–Srivastava scheme is unable to be used for a multi-server environment. This paper presents an efficient and secure ID-based remote user authentication scheme using bilinear pairings. Based on the computational Diffie–Hellman assumption, we show that the proposed scheme is secure against existential forgery on adaptively chosen-message and ID attack in the random oracle model. As compared with the recently proposed pairing-based authentication schemes, our scheme has better performance in term of the computational cost and it is suitable for a multi-server environment in distributed networks. Performance analysis and experimental data of related pairing operations on smartcards are given to demonstrate that our scheme is well suited for mobile devices with limited computing capability.

Recently, Tseng et al. proposed an improvement on Peyravian and Zunic's protected password transmission scheme and protected changing scheme to remove some security flaws. However, as we will point out in this paper, any adversary can intercept the request for changing the password sent by a legal user and modify it with a wrong password. Furthermore, we shall also propose an improved version of their protected password changing scheme to help it out of the trouble.

Peyravian and Zunic (2000) proposed a password transmission scheme and a password change scheme over an insecure network. Their proposed solutions do not require the use of any symmetric-key or public-key cryptosystems. However, this article points out that their schemes have several security flaws for practical applications. A slight improvement on their schemes is proposed in this paper to remove the security flaws.