• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.5
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• pp.2674-2697
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• 2019

Identity authentication is a crucial line of defense for network security, and passwords are still the mainstream of identity authentication. So far trawling password attacking has been extensively studied, but the research related with personal information is always sporadic. Probabilistic context-free grammar (PCFG) and Markov chain-based models perform greatly well in trawling guessing. In this paper we propose a systematic targeted attacking model based on structure partition and string reorganization by migrating the above two models to targeted attacking, denoted as TG-SPSR. In structure partition phase, besides dividing passwords to basic structure similar to PCFG, we additionally define a trajectory-based keyboard pattern in the basic grammar and introduce index bits to accurately characterize the position of special characters. Moreover, we also construct a BiLSTM recurrent neural network classifier to characterize the behavior of password reuse and modification after defining nine kinds of modification rules. Extensive experimental results indicate that in online attacking, TG-SPSR outperforms traditional trawling attacking algorithms by average about 275%, and respectively outperforms its foremost counterparts, Personal-PCFG, TarGuess-I, by about 70% and 19%; In offline attacking, TG-SPSR outperforms traditional trawling attacking algorithms by average about 90%, outperforms Personal-PCFG and TarGuess-I by 85% and 30%, respectively.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.11
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• pp.503-510
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• 2013

Recently, the rapid development of network technology has enabled people to use various services on the internet. However, the existing password-based user authentication system used in the internet environment requires a password table, which is a potential security threat as it could be leaked by an insider. To solve this issue, remote user authentication methods that do not require a user password table have been proposed. Regarding remote user authentication using a smart card in particular, various methods have been suggested to reduce expenses and to improve stability and efficiency, but the possibility of impersonation attacks and password-guessing attacks using information saved in a user's smart card still exist. Therefore, this study proposes a remote user authentication method that can safeguard against impersonation attacks and password guessing attacks, by analyzing weak points of conventional methods and creating a smart card's ID and password that are based on the user's ID and password.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.7
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• pp.1367-1372
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• 2007

This paper suggests One-time Password key exchange authentication technique for a strong authentication based on MANET and through identify wireless environment security vulnerabilities, analyzes current authentication techniques. The suggested authentication technique consists of 3 steps: Routing, Registration, and Running. The Routing step sets a safe route using AODV protocol. The Registration and Running step apply the One-time password S/key and the DH-EKE based on the password, for source node authentication. In setting the Session key for safe packet transmission and data encryption, the suggested authentication technique encrypts message as H(pwd) verifiers, performs key exchange and utilizes One time password for the password possession verification and the efficiency enhancement. EKE sets end to end session key using the DH-EKE in which it expounds the identifier to hash function with the modula exponent. A safe session key exchange is possible through encryption of the H(pwd) verifier. The suggested authentication technique requires exponentiation and is applicable in the wireless network environment because it transmits data at a time for key sharing, which proves it is a strong and reliable authentication technique based on the complete MANET.

• Journal of Korea Society of Industrial Information Systems
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• v.10 no.2
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• pp.59-66
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• 2005

Recently, Ku and Chen(Ku-Chen) showed some problems in the password based remote user authentication scheme using smartcards proposed by Chien et al. and proposed an improvement from it. This paper shows some weaknesses in the Ku-Chen's scheme, especially the replay attacks, and proposes two authentication protocols to solve the problems in it. First of all, an authentication protocol using synchronized timestamps is proposed to solve the problem in the Ku-Chen's protocol. Then, a nonce-based authentication protocol is proposed to solve the inherent problems in the synchronized timestamp-based authentication protocols. The proposed authentication protocols support the advantages in the previous password-based authentication protocols and solve the problems in them effectively.

• Journal of Information Technology Services
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• v.8 no.2
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• pp.117-136
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• 2009

Over the years a password has been used as a popular authentication method between a client and a server because of its easy-to-memorize property. But, most password-based authentication services have focused on a same password authentication scheme which provides an authentication and key exchange between a client and a server with the same password. With rapid change of communication environments in the fields such as mobile networks, home networking, etc., the end-to-end security allowing users to hold different password is considered as one of main concerns. In this paper, we consider a new authentication service of how each client with different own password is able to authenticate each other, which is a quite new service paradigm among the existing services. This new service can be used in the current or next generation network environment where a mobile user in cell A wants to establish a secure end-to-end channel with users in ceil B, C, and D using only their memorable passwords. This end-to-end security service minimizes the interferences from the operator controlled by network components. To achieve this end-to-end security, we propose an authentication and key exchange service for group users in different realm, and analyze its security in a formal way. We also discuss a generic construction with the existing authentication schemes.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.12
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• pp.525-532
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• 2013

Recently smartphones, tablet, etc. Various types of smart terminal is due to the increased security in mobile devices are becoming an issue. How to enter the password in this environment is a very important issue. Difficult to have a secure password input device on various types of mobile devices. In addition you enter on the touch screen the password of character, uncomfortable and it is vulnerable to SSA attack. Therefore, in this paper provide for defense the SSA(Shoulder Surfing Attacks) and useful password input mechanism is proposed with Smartphone GPS uses a value generated via a graphical password techniques.

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

• Journal of Korean Institute of Industrial Engineers
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• v.42 no.4
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• pp.280-289
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• 2016

User authentication is an important issue on computer network systems. Most of the current computer network systems use the ID-password string match as the primary user authentication method. However, in password-based authentication, whoever acquires the password of a valid user can access the system without any restrictions. In this paper, we present a keystroke dynamics-based user authentication to resolve limitations of the password-based authentication. Since most previous studies employed a fixed-length text as an input data, we aims at enhancing the authentication performance by combining four different variable creation methods from a variable-length free text as an input data. As authentication algorithms, four one-class classifiers are employed. We verify the proposed approach through an experiment based on actual keystroke data collected from 100 participants who provided more than 17,000 keystrokes for both Korean and English. The experimental results show that our proposed method significantly improve the authentication performance compared to the existing approaches.

• Journal of Digital Convergence
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• v.11 no.12
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• pp.423-430
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• 2013

With the active Internet e-commerce and the financial sector, mutual authentication between users and service providers has become very important. Because ID- and password-based authentication is of low security, one-time password authentication methods are widely used. The existing one-time password authentication scheme of S/Key authentication method is fraught with a number of issues in addition to plain text transmission, and the method of Kim Gong-ki et al. does not offer suggestions for session key generation and distribution method. Proposed in this paper is a protocol that solves these problems.

• Journal of information and communication convergence engineering
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• v.7 no.3
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• pp.340-344
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• 2009

Multi-server password authentication schemes enable remote users to obtain service from multiple servers with single password without separately registering to each server. In 2007, Hu-Niu-Yang proposed an improved efficient password authenticated key agreement scheme for multi-server architecture based on Chang-Lee's scheme proposed in 2004. This scheme is claimed to be more efficient and is able to overcome a few existing deficiencies in Chang-Lee's scheme. However, we find false claim of forward secrecy property and some potential threats such as offline dictionary attack, key-compromise attack, and poor reparability in their scheme. In this paper, we will discuss these issues in depth.