• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.12
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• pp.6188-6204
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• 2017

Over the years, more password-based authentication key agreement schemes using chaotic maps were susceptible to attack by off-line password guess attack. This work approaches this problem by a new method--new theorem of chaotic maps: $T_{a+b}(X)+T_{a-b}(X)=2T_a(X)T_b(X)$,(a>b). In fact, this method can be used to design two-party, three-party, even in N-party intelligently. For the sake of brevity and readability, only a two-party instance: a novel Two-party Password-Authenticated Key Agreement Protocol is proposed for resisting password guess attack in this work. Compared with the related literatures recently, our proposed scheme can be not only own high efficiency and unique functionality, but is also robust to various attacks and achieves perfect forward secrecy. For capturing improved ratio of security and efficiency intuitively, the paper firstly proposes a new parameter called security/efficiency ratio(S/E Ratio). The higher the value of the S/E Ratio, the better it is. Finally, we give the security proof and the efficiency analysis of our proposed scheme.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.4
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• pp.75-90
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• 2004

At Asiacrypt 2003, Shin et al., have proposed a new class for Authenticated Key Establishment (AKE) protocol named Leakage-Resilient AKE ${(LR-AKE)}^{[1]}$. The authenticity of LR-AKE is based on a user's password and his/her stored secrets in both client side and server side. In their LR-AKE protocol, no TRM(Tamper Resistant Modules) is required and leakage of the stored secrets from $.$my side does not reveal my critical information on the password. This property is useful when the following situation is considered :(1) Stored secrets may leak out ;(2) A user communicates with a lot of servers ;(3) A user remembers only one password. The other AKE protocols, such as SSL/TLS and SSH (based or PKI), Password-Authenticated Key Exchange (PAKE) and Threshold-PAKE (T-PAKE), do not satisfy that property under the above-mentioned situation since their stored secrets (or, verification data on password) in either the client or the servers contain enough information to succeed in retrieving the relatively short password with off-line exhaustive search. As of now, the LR-AKE protocol is the currently horn solution. In this paper, we prove its security of the LR-AKE protocol in the standard model. Our security analysis shows that the LR-AKE Protocol is provably secure under the assumptions that DDH (Decisional Diffie-Hellman) problem is hard and MACs are selectively unforgeable against partially chosen message attacks (which is a weaker notion than being existentially unforgeable against chosen message attacks).

• Journal of information and communication convergence engineering
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• v.3 no.4
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• pp.213-216
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• 2005

Almost all network systems provide an authentication mechanism based on user ID and password. In such system, it is easy to obtain the user password using a sniffer program with illegal eavesdropping. The one-time password and challenge-response method are useful authentication schemes that protect the user passwords against eavesdropping. In client/server environments, the one-time password scheme using time is especially useful because it solves the synchronization problem. It is the stability that is based on Square Root Problem, and we would like to suggest PBI(password Based Identification), enhancing the stability, for all of the well-known attacks by now including Off-line dictionary attack, password file compromise, Server and so on. The PBI is also excellent in the aspect of the performance.

• Journal of information and communication convergence engineering
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• v.5 no.4
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• pp.346-350
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• 2007

Almost all network systems provide an authentication mechanism based on user ID and password. In such system, it is easy to obtain the user password using a sniffer program with illegal eavesdropping. The one-time password and challenge-response method are useful authentication schemes that protect the user passwords against eavesdropping. In client/server environments, the one-time password scheme using time is especially useful because it solves the synchronization problem. It is the stability that is based on Square Root Problem, and we would like to suggest PBSI(Password Based Secure Identification), enhancing the stability, for all of the well-known attacks by now including Off-line dictionary attack, password file compromise, Server and so on. The PBSI is also excellent in the aspect of the performance.

• Journal of information and communication convergence engineering
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• v.4 no.4
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• pp.166-169
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• 2006

Almost all network systems provide an authentication mechanism based on user ID and password. In such system, it is easy to obtain the user password using a sniffer program with illegal eavesdropping. The one-time password and challenge-response method are useful authentication schemes that protect the user passwords against eavesdropping. In client/server environments, the one-time password scheme using time is especially useful because it solves the synchronization problem. In this paper, we present a new identification scheme: OPI(One Pass Identification). The security of OPI is based on the square root problem, and OPI is secure: against the well known attacks including pre-play attack, off-line dictionary attack and server comprise. A number of pass of OPI is one, and OPI processes the password and does not need the key. We think that OPI is excellent for the consuming time to verify the prover.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.7
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• pp.1831-1853
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• 2012

By sending periodically short bursts of traffic to reduce legit transmission control protocol (TCP) traffic, the low-rate denial of service (LDoS) attacks are hard to be detected and may endanger covertly a network for a long period. Traditionally, LDoS detecting methods mainly concentrate on the attack stream with feature matching, and only a limited number of attack patterns can be detected off-line with high cost. Recent researches divert focus from the attack stream to the traffic anomalies induced by LDoS attacks, which can detect more kinds of attacks with higher efficiency. However, the limited number of abnormal characteristics and the inadequacy of judgment rules may cause wrong decision in some particular situations. In this paper, we address the problem of detecting LDoS attacks and present a scheme based on the fluctuant features of legit TCP and acknowledgment (ACK) traffic. In the scheme, we define judgment criteria which used to identify LDoS attacks in real time at an optimal detection cost. We evaluate the performance of our strategy in real-world network topologies. Simulations results clearly demonstrate the superiority of the method proposed in detecting LDoS attacks.

• Journal of the Korea Society of Computer and Information
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• v.15 no.2
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• pp.119-125
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• 2010

Recently Hsiang-Shih proposed the user authentication scheme to improve Yoon et al's scheme. But the proposed scheme has not been satisfied security requirements considering in the user authentication scheme using the password based smart card. In this paper, we proved that Hsiang-Shih's scheme is vulnerable to the off-line password guessing attack. In other words, the attacker can get the user's password using the off-line password guessing attack on the scheme when the attacker steals the user's smart card and extracts the information in the smart card. Also, the improved scheme based on the hash function and random number was introduced, thus preventing the attacks, such as password guessing attack, forgery attack and impersonation attack etc. And we suggested the effective mutual authentication scheme that can authenticate each other at the same time between the user and server.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.5
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• pp.2718-2731
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• 2019

Conjunctive keyword search encryption is an important technique for protecting sensitive data that is outsourced to cloud servers. However, the process of searching outsourced data may facilitate the leakage of sensitive data. Thus, an efficient data search approach with high security is critical. To solve this problem, an efficient conjunctive keyword search scheme based on ciphertext-policy attribute-based encryption is proposed for cloud storage environment. This paper proposes an efficient mechanism for removing the secure channel and resisting off-line keyword-guessing attacks. The storage overhead and the computational complexity are regardless of the number of keywords. This scheme is proved adaptively secure based on the decisional bilinear Diffie-Hellman assumption in the standard model. Finally, the results of theoretical analysis and experimental simulation show that the proposed scheme has advantages in security, storage overhead and efficiency, and it is more suitable for practical applications.

• Journal of the Korea Society of Computer and Information
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• v.15 no.3
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• pp.91-97
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• 2010

Recently Hu-Niu-Yang proposed the user authentication scheme to improve Liu et al's scheme. But the Hu-Niu-Yang's scheme has not been satisfied security requirements considering in the user authentication scheme using the password based smart card. In this paper, we proved that Hu-Niu-Yang's scheme is vulnerable to the off-line password guessing attack in case that the attacker steals the user's smart card and extracts the information in the smart card. Also, the improved user authentication scheme solving the security vulnerability was introduced, thus preventing the attacks, such as password guessing attack, forgery attack impersonation attack, and replay attack. For preventing those attacks, the our proposed scheme need more hash functions and exclusive-OR operations than Hu-Niu-Yang's scheme.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.2
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• pp.978-1002
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• 2019

With the rapid development of the Internet of Things, the problem of privacy protection has been paid great attention. Recently, Nikooghadam et al. pointed out that Kumari et al.'s protocol can neither resist off-line guessing attack nor preserve user anonymity. Moreover, the authors also proposed an authentication supportive session initial protocol, claiming to resist various vulnerability attacks. Unfortunately, this paper proves that the authentication protocols of Kumari et al. and Nikooghadam et al. have neither the ability to preserve perfect forward secrecy nor the ability to resist key-compromise impersonation attack. In order to remedy such flaws in their protocols, we design a lightweight authentication protocol using elliptic curve cryptography. By way of informal security analysis, it is shown that the proposed protocol can both resist a variety of attacks and provide more security. Afterward, it is also proved that the protocol is resistant against active and passive attacks under Dolev-Yao model by means of Burrows-Abadi-Needham logic (BAN-Logic), and fulfills mutual authentication using Automated Validation of Internet Security Protocols and Applications (AVISPA) software. Subsequently, we compare the protocol with the related scheme in terms of computational complexity and security. The comparative analytics witness that the proposed protocol is more suitable for practical application scenarios.