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Thickness Effect on Thermal Stability by Phase Transition of Single Crystal Hematite Nanorings
Le Li,Fagen Li,XiaoPing Zhang,JUN WANG 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.6
Single-crystal hematite (α-Fe2O3) nanorings with three different thicknesses were synthesized by a hydrothermal method. The results of X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) show that the nanorings are single-crystal and have relatively uniform outer diameters of 160 nm, and heights of about 100 nm. Magnetic measurements up to 920K have been performed on hydrothermally synthesized α-Fe2O3 nanorings and nanoparticles using a quantum design vibrating sample magnetometer. A high temperature phase transition of thermal stability ( α-Fe2O3 to Fe3O4) occurs when magnetic measurement was performed under high vacuum ( < 9.5 x 10-5 Torr). The phase transition temperature is 670 K for nanorings with thickness of ~30 nm, 718 K for nanorings with thickness of ~50 nm, 678 K for nanorings with thickness of ~65 nm, and 640 K for ~35 nm nanoparticles. This data show better thermal stability of nanorings with the thickness of ~50 nm than the other two kinds of nanoring samples The Néel temperature (TN) of α-Fe2O3 nanorings with the thickness of ~50 nm is determined to be 937.2 K by magnetic measurement for the first time, about 22.8 K below the bulk value. The small reduction of the TN of the α-Fe2O3 nanorings is consistent with the finite-size scaling theory.
Xingbing Fu,Fagen Li,Shengke Zeng 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.1
In this work, an oblivious transfer with complex access control scheme that is constructed based on ciphertext policy attribute based encryption (CP-ABE) scheme is proposed. In this scheme, the database server can enforce fine grained access control for each record where the authorized user is allowed to access, but the unauthorized user cannot, whereas it learns neither which record a user accesses, nor which attributes a user has. This scheme has the advantages as follows: First, it allows the expressive access control policies where access structures are based on linear secret sharing scheme that directly supports AND, OR and Threshold gates. Second, the communication complexity in this scheme is constant in the numbers of records which have been accessed. Third, this scheme is constructed in prime order bilinear group. Fourth, this scheme is secure in the standard model. To the best of our knowledge, this scheme is the first to obtain these features simultaneously.
An Efficient Identity-Based Deniable Authenticated Encryption Scheme
( Weifeng Wu ),( Fagen Li ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.5
Deniable authentication protocol allows a sender to deny his/her involvement after the protocol run and a receiver can identify the true source of a given message. Meanwhile, the receiver has no ability to convince any third party of the fact that the message was sent by the specific sender. However, most of the proposed protocols didn`t achieve confidentiality of the transmitted message. But, in some special application scenarios such as e-mail system, electronic voting and Internet negotiations, not only the property of deniable authentication but also message confidentiality are needed. To settle this problem, in this paper, we present a non-interactive identity-based deniable authenticated encryption (IBDAE) scheme using pairings. We give the security model and formal proof of the presented IBDAE scheme in the random oracle model under bilinear Diffie-Hellman (BDH) assumption.
Quantum Authentication of Classical Messages without Entangled State as Authentication Key
Xiangjun Xin,Fagen Li 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.8
Classical messages can be authenticated by traditional authentication protocols based on hash functions. The security of these protocols depends on long authentication keys, the selection of appropriate hash functions and some assumptions concerning the computational complexity of some algorithms. In this paper, by encoding the classical binary messages and binary keys as nonorthogonal quantum messages and nonorthogonal sets of states, respectively, and using quantum encrypting scheme, a new quantum authentication protocol is proposed. In our protocol, instead of entangled quantum states, the traditional binary bits, which can be easily saved, are encoded as quantum keys. Because the quantum messages are nonorthogonal, any forgery or measurement on the quantum messages will be detected with a certain probability. Our protocol allows the authentication of binary classical messages in a secure manner.
Xiangjun,Chaoyang Li,Dongsheng Chen,Fagen Li 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.5
Most of the quantum authentication protocols are used to authenticate quantum messages. In this paper, by using a pair of non-entangled qubits, a quantum authentication protocol of classical messages is proposed. In the pair of qubits, the first one is used to carry a bit message, and the second one is used as a tag to authenticate the classical message. In our protocol, a bit string instead of a sequence of maximally entangled states is used directly as an authentication key, so the authentication key can be easily stored offline. On the other hand, in our protocol, a unitary operation UA is chosen to encrypt the qubits so that the successful probability of all attacks analyzed is less than one. Our quantum authentication protocol is secure against various attacks such as the no-message attack and message attacks.
EEE-GSM : End-to-End Encryption Scheme over GSM System
Mohammed Ramadan,Guohong Du,Fagen Li,Chun Xiang Xu 보안공학연구지원센터 2016 International Journal of Security and Its Applicat Vol.10 No.6
GSM system is widely used by hundreds of millions of people. In fact there is no encryption scheme provides the reasonable security level (user-to-user encryption), it’s just provide the Air-interface encryption i.e. between the mobile station and the base station. Furthermore, there are other wireless links are vulnerable to attacks. It is therefore of great importance to provide reasonable security techniques to ensure the privacy of the mobile users especially circuit switching-based services, as well as prevent unauthorized use of the service. In this paper, a new approach is proposed to provide end-to-end encryption for the GSM system (EEE-GSM). This is achieved by using CL-PKC with some modifications and follow some assumptions in GSM system architecture in order to make the scheme compliant to the GSM cellular system. However, the proposed scheme not only efficient due to end-to-end security, but can also provide a secure system against IMSI catcher, man-in-the-middle, and replay attacks.
On the Security of a Group Key Agreement Protocol and Its Improvement with Pairings
Xiangjun Xin,Chaoyang Li,Dongsheng Chen,Fagen Li 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.2
In the paper, we analyze the security vulnerability of the key agreement protocol proposed by Lee et al.'s. We present a forgery attack to their protocol. In this attack, the adversary can modify the signed message and forge a new signature, which can pass the verification. Then, we propose a new group key agreement protocol, which overcomes this security drawback. The new protocol can be proved to be secure under Elliptic Curve Discrete Logarithm Problem, Bilinear Computational Diffie–Hellman Problem and Square-Exponent Problem. On the other hand, in the new protocol, only three pairing operations are used, so it is more efficient. Our protocol is also a contributory group key agreement protocol.
Quantum Authentication Protocol for Classical Messages Based on Bell states and Hash Function
Xiangjun Xin,Xiaolin Hua,Jianpo Song,Fagen Li 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.7
Quantum authentication protocols can be used to authenticate both quantum messages and classical messages. In this paper, a new quantum authentication protocol of classical messages is proposed. In our protocol, a sequence of Bell states is shared by the message sender and the corresponding receiver. This sequence is used as the authentication key. Four different unitary operations U0, U1, U2 and U3 are used to encode a classical message m and its hash value h(m) into a sequence of Bell states. To authenticate the classical message, the message receiver extracts m and h(m) from the qubits owned by himself/herself, and verifies whether h(m) matches m. The adversary’s disturbance to the quantum channel can be detected by checking whether h(m) matches m. The transmitted message has the properties of both secrecy and authentication. Our quantum authentication protocol is secure against message attack and no-message attack.
Conditional Mutual Information-Based Feature Selection Analyzing for Synergy and Redundancy
Hongrong Cheng,Zhiguang Qin,Chaosheng Feng,Yong Wang,Fagen Li 한국전자통신연구원 2011 ETRI Journal Vol.33 No.2
Battiti’s mutual information feature selector (MIFS) and its variant algorithms are used for many classification applications. Since they ignore feature synergy, MIFS and its variants may cause a big bias when features are combined to cooperate together. Besides, MIFS and its variants estimate feature redundancy regardless of the corresponding classification task. In this paper, we propose an automated greedy feature selection algorithm called conditional mutual information-based feature selection (CMIFS). Based on the link between interaction information and conditional mutual information, CMIFS takes account of both redundancy and synergy interactions of features and identifies discriminative features. In addition, CMIFS combines feature redundancy evaluation with classification tasks. It can decrease the probability of mistaking important features as redundant features in searching process. The experimental results show that CMIFS can achieve higher best-classification-accuracy than MIFS and its variants, with the same or less (nearly 50%) number of features.