• Electronics and Telecommunications Trends
• /
• v.33 no.1
• /
• pp.57-67
• /
• 2018

Modern users are intensifying their use of online services every day. In addition, hackers are attempting to execute advanced attacks to steal personal information protected using existing authentication technologies. However, existing authentication methods require an explicit authentication procedure for the user, and do not conduct identity verification in the middle of the authentication session. In this paper, we introduce an implicit continuous authentication technology to overcome the limitations of existing authentication technology. Implicit continuous authentication is a technique for continuously authenticating users without explicit intervention by utilizing their behavioral and environmental information. This can improve the level of security by verifying the user's identity during the authentication session without the burden of an explicit authentication procedure. In addition, we briefly introduce the definition, key features, applicable algorithms, and recent research trends for various authentication technologies that can be used as an implicit continuous authentication technology.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.27 no.5
• /
• pp.1033-1047
• /
• 2017

Traditional explicit authentication, which requires awareness of the user's authentication process, is a burden on the user, which is one of main reasons why users tend not to employ authentication. In this paper, we try to reduce such cost by employing implicit authentication methods, such as biometrics and location based authentication methods. We define the 4-level security assurance model, where each level is mapped to an explicit authentication method. We implement our model as an Android application, where the implicit authentication methods are touch-stroke dynamics-based, face recognition based, and the location based authentication. From user experiment, we could show that the authentication cost is reduced by 14.9% compared to password authentication-only case and by 21.7% compared to the case where 6-digit PIN authentication is solely used.

• International Journal of Contents
• /
• v.9 no.2
• /
• pp.14-21
• /
• 2013

Current smartphone authentication systems are deemed inconvenient and difficult for users on remembering their password as well as privacy issues on stolen or forged biometrics. New authentication system is demanded to be implicit to users with very minimum user involvement being. This idea aims towards a future model of authentication system for smartphones users without users realizing them being authenticated. We use the most frequent activity that users carry out with their smartphone, which is the calling activity. We derive two basics related interactions that are first factor being arm's flex (AF) action to pick a phone to be near ones' ears and then once getting near ear using second factor from ear shape image. Here, we combine behavior biometrics from AF in first factor and physical biometrics from ear image in second factor. Our study shows our dual-factor authentication system does not require explicit user interaction thereby improving convenience and alleviating burden from users from persistent necessity to remember password. These findings will augment development of novel implicit authentication system being transparent, easier, and unobtrusive for users.

• Journal of Korea Multimedia Society
• /
• v.17 no.8
• /
• pp.968-976
• /
• 2014

Authentication methods on smartphone are demanded to be implicit to users with minimum users' interaction. Existing authentication methods (e.g. PINs, passwords, visual patterns, etc.) are not effectively considering remembrance and privacy issues. Behavioral biometrics such as keystroke dynamics and gait biometrics can be acquired easily and implicitly by using integrated sensors on smartphone. We propose a biometric model involving keystroke dynamics for implicit authentication on smartphone. We first design a feature extraction method for keystroke dynamics. And then, we build a fusion model of keystroke dynamics and gait to improve the authentication performance of single behavioral biometric on smartphone. We operate the fusion at both feature extraction level and matching score level. Experiment using linear Support Vector Machines (SVM) classifier reveals that the best results are achieved with score fusion: a recognition rate approximately 97.86% under identification mode and an error rate approximately 1.11% under authentication mode.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.13 no.3
• /
• pp.1502-1522
• /
• 2019

Leakage of secret keys may be the most devastating problem in public key cryptosystems because it means that all security guarantees are missing. The forward security mechanism allows users to update secret keys frequently without updating public keys. Meanwhile, it ensures that an attacker is unable to derive a user's secret keys for any past time, even if it compromises the user's current secret key. Therefore, it offers an effective cryptographic approach to address the private key leakage problem. As an extension of the forward security mechanism in certificate-based public key cryptography, forward-secure certificate-based signature (FS-CBS) has many appealing merits, such as no key escrow, no secure channel and implicit authentication. Until now, there is only one FS-CBS scheme that does not employ the random oracles. Unfortunately, our cryptanalysis indicates that the scheme is subject to the security vulnerability due to the existential forgery attack from the malicious CA. Our attack demonstrates that a CA can destroy its existential unforgeability by implanting trapdoors in system parameters without knowing the target user's secret key. Therefore, it is fair to say that to design a FS-CBS scheme secure against malicious CAs without lying random oracles is still an unsolved issue. To address this problem, we put forward an enhanced FS-CBS scheme without random oracles. Our FS-CBS scheme not only fixes the security weakness in the original scheme, but also significantly optimizes the scheme efficiency. In the standard model, we formally prove its security under the complexity assumption of the square computational Diffie-Hellman problem. In addition, the comparison with the original FS-CBS scheme shows that our scheme offers stronger security guarantee and enjoys better performance.