Huy Hoang Ngo

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In the present work, a block cipher is presented which deals with a dynamic symmetric key cryptographic method using substitution and transposition technique. In this work a dynamic secret key is generated using Linear Congruential Generator (LCG). The striking feature of the present work is creation of a new secret key for every pair of encryption and(More)
Authentication is the most important component to protect information system from unauthorized access. Because mobile devices have resource limitations, current existing authentication methods experience security, efficiency, flexibility and scalability problems in wireless network services. Although many access control methods utilize both individuals and(More)
This paper presents a new hybrid group key management scheme for sensitive information systems which allows group members to share information securely. By classifying users into two categories, the complexities of rekeying operation on key servers are reduced while privacy for individuals is also protected. A formal analysis is provided to verify the(More)
Authorization and authentication services are the major components protecting integrity and authenticity. Authorization control service provides a mechanism to verify user permission to access services. In wireless networks, not only users may change roles but also services can be added, removed or modified more frequently. Although Role-Based Access(More)
In modern security models, cryptography plays a fundamental role in protecting data integrity and confidentiality in information systems. However, cryptography itself is subject to cryptanalysis attacks. To reduce the crypt-analysis attack risk, a dynamic key theory is presented and analyzed in this paper. Because these dynamic keys are one-time used(More)
The current paper presents preliminary work towards the integration of the Fujisaki model into the VnVoice Vietnamese TTS system, based on a set of rules to control the F0 contour. A speech corpus consisting of 20 sentences was compiled. Each of the sentences can have various meanings depending on the tone associated with a monosyllabic keyword which it(More)
This paper presents a secure authentication and authorization protocol for protecting privacy in sensitive information systems. It allows involved individuals and group participants to achieve high security levels and tight authorization control. The need of long term shared secrets to authenticate individuals and group users is eradicated in the proposed(More)