• 한국IT서비스학회지
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• 제8권2호
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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.

• 디지털산업정보학회논문지
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• 제5권4호
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• pp.139-150
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• 2009

Authentication and key exchange are fundamental for establishing secure communication channels over public insecure networks. Password-based protocols for authenticated key exchange are designed to work even when user authentication is done via the use of passwords drawn from a small known set of values. There have been many protocols proposed over the years for password authenticated key exchange in the three-party scenario, in which two clients attempt to establish a secret key interacting with one same authentication server. However, little has been done for password authenticated key exchange in the more general and realistic four-party setting, where two clients trying to establish a secret key are registered with different authentication servers. In fact, the recent protocol by Yeh and Sun seems to be the only password authenticated key exchange protocol in the four-party setting. But, the Yeh-Sun protocol adopts the so called "hybrid model", in which each client needs not only to remember a password shared with the server but also to store and manage the server's public key. In some sense, this hybrid approach obviates the reason for considering password authenticated protocols in the first place; it is difficult for humans to securely manage long cryptographic keys. In this work, we introduce a key agreement protocol and a key distribution protocol, respectively, that requires each client only to remember a password shared with its authentication server.

• 대한산업공학회지
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• 제42권4호
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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.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제2권6호
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• pp.312-332
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• 2008

Password-based authentication key exchange (PAKE) protocols in the literature typically assume a password that is shared between a client and a server. PAKE has been applied in various environments, especially in the “client-server” applications of remotely accessed systems, such as e-banking. With the rapid developments in modern communication environments, such as ad-hoc networks and ubiquitous computing, it is customary to construct a secure peer-to-peer channel, which is quite a different paradigm from existing paradigms. In such a peer-to-peer channel, it would be much more common for users to not share a password with others. In this paper, we consider password-based authentication key exchange in the three-party setting, where two users do not share a password between themselves but only with one server. The users make a session-key by using their different passwords with the help of the server. We propose an efficient password-based authentication key exchange protocol with different passwords that achieves forward secrecy in the standard model. The protocol requires parties to only memorize human-memorable passwords; all other information that is necessary to run the protocol is made public. The protocol is also light-weighted, i.e., it requires only three rounds and four modular exponentiations per user. In fact, this amount of computation and the number of rounds are comparable to the most efficient password-based authentication key exchange protocol in the random-oracle model. The dispensation of random oracles in the protocol does not require the security of any expensive signature schemes or zero-knowlegde proofs.

• 산업융합연구
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• 제21권9호
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• pp.49-56
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• 2023

개인별 서비스를 위한 ID 기반 인증으로 ID가 식별정보로 활용되고, 패스워드가 사용자 인증에 사용된다. 안전한 사용자 인증을 위해 패스워드는 클라이언트에서 해시값으로 생성하여 서버에 전달되고 서버에 저장된 정보와 해시값을 비교하며 인증을 수행한다. 하지만 패스워드의 해시값은 패스워드에서 한 개라도 틀리면 전혀 다른 해시값이 생성되어 사용자 인증에 실패하여 패스워드에 의한 다양한 기능을 적용할 수 없다. 본 연구에서는 입력된 패스워드의 해시값을 허수를 포함하여 여러 개 생성하고 서버에 전송해서 인증을 수행한다. 또한 제안 기법에서는 여러 권한을 가진 사용자가 하나의 계정으로 다양한 권한을 부여받을 수 있도록 패스워드에 따라 권한을 차등적으로 부여할 수 있다. 제안 기법을 통해 허수 패스워드를 생성함으로써 엿보기 공격을 차단하고, 패스워드 기반으로 권한을 부여하므로 다양한 권한을 가진 사용자에게 편리성을 제공할 수 있다.

• 한국통신학회논문지
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• 제38B권3호
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• pp.190-198
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• 2013

사용자가 원하는 서비스가 여러 개의 서버에 분산되어 있을 수 있기 때문에 다수의 서버가 존재하는 다중서버 환경을 위한 인증기법은 웹서비스를 이용할 때 반드시 필요하다. 일반적으로 Password를 사용하는 방법이 적용되나 안전성 측면에서 취약하고 서버마다 다른 Identity(ID)와 Password를 사용하는 것은 불편하다. 그래서 사용자가 사용하는 여러 서버에 접속할 때 항상 동일한 ID를 사용하는 것이 허용되나, 다양한 공격에 노출될 수 있다. 본 논문에서는 서버가 여러 개 존재하는 환경에서 원격지에 있는 사용자는 하나의 스마트카드만 사용하여 다양한 서비스를 편리하고 안전하게 받을 수 있는 인증기법을 제안한다. 추가로 제안한 기법의 안전성을 공격 유형별로 나누어 분석하고, 기존 방법과 성능비교를 통하여 제안하는 기법이 효율적임을 보인다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권12호
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• pp.4987-5014
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• 2015

The bilinear pairing, also known as Weil pairing or Tate pairing, is widely used in cryptography and its properties help to construct cryptographic schemes for different applications in which the security of the transmitted data is a major concern. In remote login authentication schemes, there are two major requirements: i) proving the identity of a user and the server for legitimacy without exposing their private keys and ii) freedom for a user to choose and change his password (private key) efficiently. Most of the existing methods based on the bilinear property have some security breaches due to the lack of features and the design issues. In this paper, we develop a new scheme using the bilinear property of an elliptic point and the biometric characteristics. Our method provides many features along with three major goals. a) Checking the correctness of the password before sending the authentication message, which prevents the wastage of communication cost; b) Efficient password change phase in which the user is asked to give a new password after checking the correctness of the current password without involving the server; c) User anonymity - enforcing the suitability of our scheme for applications in which a user does not want to disclose his identity. We use BAN logic to ensure the mutual authentication and session key agreement properties. The paper provides informal security analysis to illustrate that our scheme resists all the security attacks. Furthermore, we use the AVISPA tool for formal security verification of our scheme.

• 한국정보통신학회논문지
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• 제20권12호
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• pp.2289-2296
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• 2016

사용자 계정 발급 시에 적용되는 패스워드 생성 규칙이 웹사이트 별로 다른 경우가 많아 사용자가 패스워드를 기억하기 힘들고 잦은 입력 오류로 인해 패스워드 재설정 단계를 거쳐야 하는 시간 낭비를 초래한다. 이러한 문제를 해결하기 위해 본 논문에서는 사용자 인증 단계에서 패스워드가 일치하지 않는 경우 패스워드 재설정 단계를 거치는 것이 아니라 회원 가입시에 부가적으로 등록한 기본 패스워드와 개인 정보 기반의 추가적인 인증을 거쳐 로그인할 수 있도록 하는 새로운 인증 방식을 제안하였다. 이 방식은 기존의 방식과 동등한 수준의 보안성을 제공하면서도 패스워드 재설정에 따르는 트랜잭션 수나 소요 시간이 절반 정도에 불과해 효율적인 방식으로 볼 수 있다.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제7권2호
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• pp.41-48
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• 2018

지금까지 피싱에 대응하기 위한 여러 연구가 진행되어 왔다. 가장 대표적인 안티 피싱 방법은 피싱 사이트의 URL 정보를 미리 수집한 뒤, 사용자가 방문하는 사이트의 URL과 미리 저장된 정보를 비교하여 피싱을 탐지하는 방법이다. 하지만 이러한 블랙리스트 기반의 안티피싱 방법은 새로운 피싱 사이트를 탐지하지 못하는 한계를 갖는다. 이에 다양한 안티 피싱 인증 프로토콜이 제안되어 왔지만 대부분 인증과정에서 공개키와 비밀키를 필요로 한다. 이에 본 논문에서는 피싱 공격에 안전한 패스워드 기반 상호 인증 프로토콜을 제안한다. 제안된 프로토콜에서 클라이언트와 서버간의 상호 인증은 패스워드 정보가 포함된 인증 메시지를 통해 수행된다. 인증 과정에서 사용되는 인증 메시지에는 패스워드 원본이 아닌 패스워드의 해시 값이 포함되며, 인증 시 매번 다른 메시지가 사용되기 때문에 재생공격, 도청 공격에 안전하다. 또한, 상호 인증을 수행하기 때문에 중간자 공격에 안전하며, 인증을 위한 별도의 키 발급 과정이 필요없다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권10호
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• pp.2844-2861
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• 2023

Internet is the most prevailing word being used nowadays. Over the years, people are becoming more dependent on the internet as it makes their job easier. This became a part of everyone's life as a means of communication in almost every area like financial transactions, education, and personal-health operations. A lot of data is being converted to digital and made online. Many researchers have proposed different authentication factors - biometric and/or non-biometric authentication factors - as the first line of defense to secure online data. Among all those factors, passwords and passphrases are being used by many users around the world. However, the usability of these factors is low. Also, the passwords are easily susceptible to brute force and dictionary attacks. This paper proposes the generation of a novel passcode from the hybrid authentication factor - sound. The proposed passcode is evaluated for its strength to resist brute-force and dictionary attacks using the Shannon entropy and Passcode (or password) entropy formulae. Also, the passcode is evaluated for its usability. The entropy value of the proposed is 658.2. This is higher than that of other authentication factors. Like, for a 6-digit pin - the entropy value was 13.2, 101.4 for Password with Passphrase combined with Keystroke dynamics and 193 for fingerprint, and 30 for voice biometrics. The proposed novel passcode is far much better than other authentication factors when compared with their corresponding strength and usability values.