• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.9 no.12
• /
• pp.5135-5149
• /
• 2015

Communications among multi-party must be fast, cost effective and secure. Today's computing environments such as internet conference, multi-user games and many more applications involve multi-party. All participants together establish a common session key to enable multi-party and secure exchange of messages. Multi-party password-based authenticated key exchange scheme allows users to communicate securely over an insecure network by using easy-to-remember password. Kwon et al. proposed a practical three-party password-based authenticated key exchange (3-PAKE) scheme to allow two users to establish a session key through a server without pre-sharing a password between users. However, Kwon et al.'s scheme cannot meet the security requirements of key authentication, key confirmation and anonymity. In this paper, we present a novel, simple and efficient multi-party password-based authenticated key exchange (M-PAKE) scheme based on the elliptic curve cryptography for mobile environment. Our proposed scheme only requires two round-messages. Furthermore, the proposed scheme not only satisfies security requirements for PAKE scheme but also achieves efficient computation and communication.

• International Journal of Internet, Broadcasting and Communication
• /
• v.8 no.3
• /
• pp.50-57
• /
• 2016

In 2013, Li et al. proposed an improved smart card-based remote user password authentication scheme, and claimed that their scheme not only overcomes security weaknesses of the Chen et al.'s scheme but also is a more user friendly scheme compared with other schemes. In this paper, we analyze the security of Li et al.'s authentication scheme and we show that Li et al.'s authentication scheme is still insecure against the various attacks, such as the off-line password guessing attack, the forgery attack, and the session key generation attack etc. Also, we propose an improved scheme that can resist these security drawbacks of Li et al.'s authentication, even if the secret information stored in the smart card is revealed. As a result of security analysis, the improved scheme is relatively more secure against several attacks than other related schemes in terms of the security.

• International Journal of Internet, Broadcasting and Communication
• /
• v.9 no.3
• /
• pp.35-43
• /
• 2017

In 2013, Lee-Lie proposed secure smart card based authentication scheme of Zhu's authentication for TMIS which is secure against the various attacks and efficient password change. In this paper, we discuss the security of Lee-Lie's smart card-based authentication scheme, and we have shown that Lee-Lie's authentication scheme is still insecure against the various attacks. Also, we proposed the improved scheme to overcome these security problems of Lee-Lie's authentication scheme, even if the secret information stored in the smart card is revealed. As a result, we can see that the improved smart card based user authentication scheme for TMIS is secure against the insider attack, the password guessing attack, the user impersonation attack, the server masquerading attack, the session key generation attack and provides mutual authentication between the user and the telecare system.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.18 no.3
• /
• pp.3-8
• /
• 2008

Ephemeral data are easily revealed if state specific information is stored in insecure memory or a random number generator is corrupted. In this letter, we show that Nam et al.'s group key agreement scheme, which is an improvement of Bresson et al.'s scheme, is not secure against session-state reveal attacks. We then propose an improvement to fix the security flaw.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.18 no.6B
• /
• pp.207-217
• /
• 2008

Secure channels, indispensable to many applications, can be established by using an authenticated key exchange (AKE) protocol where the involving parties authenticate one another and then share authenticated session keys over insecure networks. In this paper, we introduce a new type of AKE protocols that are especially designed to minimize the damages caused by leakages of stored secrets. Such protocols are called Leakage-Resilient AKE (LR-AKE) protocols, whose motivation, design principles, several constructions, security analysis and applications are explained in detail.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
• /
• 2002.11a
• /
• pp.99-101
• /
• 2002

At ACISP'02, H.J. Kim et al.[1] proposed a new traitor tracing scheme. However, this paper show that the proposed scheme is to be insecure by presenting a conspiracy attack. Using our attack, any two subscribers can collaborate to derive the secret key of the data supplier and tell or sell it to any body. Thus, the unauthorized user can always decrypt the encrypted session key with the decrypted session key. Also the two subscribers cannot be traced by the data supplier

• IEIE Transactions on Smart Processing and Computing
• /
• v.2 no.5
• /
• pp.297-301
• /
• 2013

Key agreement protocols allow multi-parties exchanging public information to create a common secret key that is known only to those entities over an insecure network. Since Joux first published the pairing-based one round tripartite key agreement protocol, many authenticated protocols have been proposed. Unfortunately, many of them have been broken while others have been shown to be deficient in some desirable security attributes. In 2004, Cheng et al. presented two protocols aimed at strengthening Shim's certificate-based and Zhang et al.'s tripartite identity-based protocols. This paper reports that 1) In Cheng et al.'s identity-based protocol, an adversary can extract long-term private keys of all the parties involved; and 2) Cheng et al.'s certification-based protocol is weak against key integrity attacks. This paper suggests possible remedies for the security flaws in both protocols and then presents a modified Cheng et al.'s identity-based, one-round tripartite protocol that is more secure than the original protocol.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.5 no.3
• /
• pp.607-625
• /
• 2011

Two-party key exchange protocol is a mechanism in which two parties communicate with each other over an insecure channel and output the same session key. A key exchange protocol that is secure against an active adversary who can control and modify the exchanged messages is called authenticated key exchange (AKE) protocol. LaMacchia, Lauter and Mityagin presented a strong security definition for public key infrastructure (PKI) based two-pass protocol, which we call the extended Canetti-Krawczyk (eCK) security model, and some researchers have provided eCK-secure AKE protocols in recent years. However, almost all protocols are provably secure in the random oracle model or rely on a special implementation technique so-called the NAXOS trick. In this paper, we present a PKI-based two-pass AKE protocol that is secure in the eCK security model. The security of the proposed protocol is proven without random oracles (under three assumptions), and does not rely on implementation techniques such as the NAXOS trick.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.13 no.1
• /
• pp.273-278
• /
• 2013

Recently, user authentication schemes using smart cards for multi-server environment have been proposed for practical applications. In 2009, Liao-Wang proposed a secure dynamic ID based remote user authentication scheme for multi-server environment that can withstand the various possible attacks and provide user anonymity. In this paper, we analyze the security of Liao-Wang's scheme, and we show that Liao-Wang's scheme is still insecure against the forgery attack, the password guessing attack, the session key attack, and the insider attack. In addition, Liao-Wang's scheme does not provide user anonymity between the user and the server.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.7 no.5
• /
• pp.967-979
• /
• 2013

Now a day, Wireless Sensor Networks (WSNs) are being widely used in different areas one of which is healthcare services. A wireless medical sensor network senses patient's vital physiological signs through medical sensor-nodes deployed on patient's body area; and transmits these signals to devices of registered medical professionals. These sensor-nodes have low computational power and limited storage capacity. Moreover, the wireless nature of technology attracts malicious minds. Thus, proper user authentication is a prime concern before granting access to patient's sensitive and private data. Recently, P. Kumar et al. claimed to propose a strong authentication protocol for healthcare using Wireless Medical Sensor Networks (WMSN). However, we find that P. Kumar et al.'s scheme is flawed with a number of security pitfalls. Information stored inside smart card, if extracted, is enough to deceive a valid user. Adversary can not only access patient's physiological data on behalf of a valid user without knowing actual password, can also send fake/irrelevant information about patient by playing role of medical sensor-node. Besides, adversary can guess a user's password and is able to compute the session key shared between user and medical sensor-nodes. Thus, the scheme looses message confidentiality. Additionally, the scheme fails to resist insider attack and lacks user anonymity.