Security improvement on an anonymous key agreement protocol based on chaotic maps

In 2009, Tseng et al. proposed a password sharing and chaotic map based key agreement protocol (Tseng et al.’s protocol). They claimed that the protocol provided mutual authentication between a server and a user, and allowed the user to anonymously interact with the server to establish a shared session key. However, in 2011, Niu et al. have proved that Tseng et al.’s protocol cannot guarantee user anonymity and protocol security when there is an internal adversary who is a legitimate user. Also it cannot provide perfect forward secrecy. Then Niu et al. introduced a trust third party (TTP) into their protocol designing (Niu et al.’s protocol). But according to our research, Niu et al.’s protocol is found to have several unsatisfactory drawbacks. Based on reconsidering Tseng et al.’s protocol without introducing TTP, we give some improvements to meet the original security and performance requirements. Meanwhile our proposed protocol overcomes the security flaws of Tseng et al.’s protocol.     

Weakness and improvement on Wang–Li–Tie’s user-friendly remote authentication scheme

In an open network environment, the remote authentication scheme using smart cards is a very practical solution to validate the legitimacy of a remote user. In 2003, Wu and Chieu presented a user-friendly remote authentication scheme using smart cards. Recently, Wang, Li, and Tie found that Wu–Chieu’s scheme is vulnerable to the forged login attack, and then presented an improvement to eliminate this vulnerability. In our opinion, the smart card plays an important role in those schemes. Therefore, we demonstrate that Wang–Li–Tie’s scheme is not secure under the smart card loss assumption. If an adversary obtains a legal user’s smart card even without the user’s corresponding password, he can easily use it to impersonate the user to pass the server’s authentication. We further propose an improved scheme to overcome this abuse of the smart card.     

Generalized Fibonacci broadcasting: An efficient VOD scheme with user bandwidth limit

Broadcasting is attractive in delivering popular videos in video-on-demand service, because the server broadcast bandwidth is independent of the number of users. However, the required server bandwidth does depend on how much bandwidth each user can use, as well as on the user's initial waiting time. This paper addresses the issue of limiting the user bandwidth, and proposes a new broadcasting scheme, named Generalized Fibonacci Broadcasting (GFB). In terms of many performance graphs, we show that, for any given combination of the server bandwidth and user bandwidth, GFB can achieve the least waiting time among all the currently known fixed-delay broadcasting schemes. Furthermore, it is very easy to implement GFB. We also demonstrate that there is a trade-off between the user waiting time and the buffer requirement at the user.     

An anonymous key agreement protocol based on chaotic maps

Recently, Tseng et al. proposed a novel key agreement protocol based on chaotic maps. They claimed that the protocol achieved session key agreement between a server and a user, and allowed the user to anonymously interact with the server. This paper, however, will demonstrate that Tseng et al.’s protocol can not guarantee user anonymity and protocol security against an insider adversary who is a legal user, and it can not provide perfect forward secrecy. Furthermore, the current paper presents a new key agreement protocol based on Chebyshev chaotic map in order to conquer these problems. In contrast with Tseng et al.’s protocol, the proposed protocol is more secure and preserves user anonymity.     

Efficiency and security problems of anonymous key agreement protocol based on chaotic maps

In 2011, Niu-Wang proposed an anonymous key agreement protocol based on chaotic maps in [Niu Y, Wang X. An anonymous key agreement protocol based on chaotic maps. Commun Nonlinear Sci Simulat 2011;16(4):1986-92]. Niu-Wang’s protocol not only achieves session key agreement between a server and a user, but also allows the user to anonymously interact with the server. Nevertheless, this paper points out that Niu-Wang’s protocol has the following efficiency and security problems: (1) The protocol has computational efficiency problem when a trusted third party decrypts the user sending message. (2) The protocol is vulnerable to Denial of Service (DoS) attack based on illegal message modification by an attacker.     

A key-lock-pair oriented access control scheme for the growth of users and files

A new access control scheme for the growth of users and files in file protection systems is proposed. Our scheme associates each user with a user key and each file with a file key. For each key, there are some corresponding locks, that can be extracted from a nonsingular matrix. Through simple operations on keys and locks, privacy decisions of the protection system can easily be revealed. Furthermore, by employing our method, whenever a new user or file is joined, the corresponding key values and lock values will be determined immediately without changing any previously defined keys and locks.     

一种云计算的隐私类型阈值模型和隐私保护方法

云计算作为一种新的计算模式,可为用户提供低成本的动态计算资源和存储资源,能充分提高资源的使用效率.但是数据隐私安全问题已成为云计算应用普及的最大挑战.为了更好管理用户的隐私数据,在基于(n+1,t+1)阈值的基础上,提出了一种基于隐私类型的(n+1,t+1)阈值隐私保护模型,结合可信的第三方服务器隔离存储模型,用户可在授权后依据数据隐私类型采用基于角色的访问控制进行相应的访问操作.安全分析表明,基于隐私类型的保护机制在方便用户按类型访问云中的数据资源同时,可以充分地实现用户数据的分类隐私保护.     

Chaotic map based key agreement with/out clock synchronization

In order to address Bergamo et al.’s attack, Xiao et al. proposed a key agreement protocol using chaotic maps. Han then presented three attacks on Xiao et al.’s protocol. To enhance the security of key agreement based on chaotic maps, Chang et al. proposed a new key agreement using passphrase, which works in clock synchronization environment. However, their protocol still has some issues: one is its passphrase is not easy to remember and much longer than password; the second one is it cannot resist guessing attack if the constructed passphrase is easy to remember and also has already existed in some rational dictionaries; the third one is it cannot work without clock synchronization. In this paper, we will present two different key agreement protocols, which can resist guessing attack. The first one works in clock synchronization environment. The second one can work without clock synchronization. They both use authenticated password for secure communications. The protocols are secure against replaying attacks and a shared session key can be established.     

Security of a key agreement protocol based on chaotic maps

Kacorev et al. proposed new public key encryption scheme using chaotic maps. Subsequently, Bergamo et al. has broken Kacorev and Tasev’s encryption scheme and then applied the attack on a key agreement protocol based on Kacorev et al.’s system. In order to address Bergamo et al.’ attack, Xiao et al. proposed a novel key agreement protocol. In this paper, we will present two attacks on Xiao et al.’s key agreement protocol using chaotic maps. Our new attack method is different from the one that Bergamo et al. developed. The proposed attacks work in a way that an adversary can prevent the user and the server from establishing a shared session key even though the adversary cannot get any private information from the user and the server’s communications.     

Adding visualization functions of DAVIS to Jasp: Mixing two Java-based statistical systems

Summary  Jasp is an experimental general purpose Java-based statistical system which adopts several new computing technologies. It has a function-based and object-oriented language, an advanced user interface, flexible extensibility and a server/client architecture with distributed computing abilities. DAVIS is, on the other hand, a stand-alone Java-based system, and is designed for providing advanced data visualization functions with easy operations by a GUI. In this paper, it is made possible to use tools of DAVIS from within Jasp, in order that the new integrated system can handle not only data filtering and statistical analysis but also data visualization. We develop a mechanism for extending the server/client system of Jasp to realize an efficient collaboration with DAVIS in the client-side. It is shown that the mechanism is straightforward and simple.     

Efficient revocable identity-based encryption via subset difference methods

Providing an efficient revocation mechanism for identity-based encryption (IBE) is very important since a user’s credential (or private key) can be expired or revealed. revocable IBE (RIBE) is an extension of IBE that provides an efficient revocation mechanism. Previous RIBE schemes essentially use the complete subtree (CS) scheme of Naor, Naor and Lotspiech (CRYPTO 2001) for key revocation. In this paper, we present a new technique for RIBE that uses the efficient subset difference (SD) scheme of Naor et al. instead of using the CS scheme to improve the size of update keys. Following our new technique, we first propose an efficient RIBE scheme in prime-order bilinear groups by combining the IBE scheme of Boneh and Boyen and the SD scheme and prove its selective security under the standard assumption. Our RIBE scheme is the first RIBE scheme in bilinear groups that has O(r) number of group elements in an update key where r is the number of revoked users. Next, we also propose another RIBE scheme in composite-order bilinear groups and prove its full security under static assumptions. Our RIBE schemes also can be integrated with the layered subset difference scheme of Halevy and Shamir (CRYPTO 2002) to reduce the size of a private key.     

Anonymity and one-way authentication in key exchange protocols

Key establishment is a crucial cryptographic primitive for building secure communication channels between two parties in a network. It has been studied extensively in theory and widely deployed in practice. In the research literature a typical protocol in the public-key setting aims for key secrecy and mutual authentication. However, there are many important practical scenarios where mutual authentication is undesirable, such as in anonymity networks like Tor, or is difficult to achieve due to insufficient public-key infrastructure at the user level, as is the case on the Internet today. In this work we are concerned with the scenario where two parties establish a private shared session key, but only one party authenticates to the other; in fact, the unauthenticated party may wish to have strong anonymity guarantees. We present a desirable set of security, authentication, and anonymity goals for this setting and develop a model which captures these properties. Our approach allows for clients to choose among different levels of authentication. We also describe an attack on a previous protocol of Øverlier and Syverson, and present a new, efficient key exchange protocol that provides one-way authentication and anonymity.     

一种灵活的基于身份的签名方案

在基于身份的密钥提取过程中,使密钥生成器在私钥中嵌入随机数,从而使得密钥提取具有较好的灵活性,使得用户对一个身份可具备多个私钥,这无疑会增加密钥使用的安全性;基于这种新的密钥提取思路,给出一个基于身份的签名体制,新的密钥提取方式使得它具有更好的安全性和灵活性;新的基于身份的签名体制中具有最少对运算,因此,与类似的方案相比,其具备较好的计算效率;新签名体制的安全性依赖于k-合谋攻击问题(k-CAAP)的困难性,其在适应性选择消息和ID攻击下具备强不可伪造性,并且其安全性证明具有紧规约性.     

Utilizing the IP Multimedia Subsystem to create an extensible service-oriented architecture

Smart Spaces provide very promising means of creating context-aware environments. Unfortunately, a lack of information about users within Smart Spaces limits their usefulness. We propose a novel solution that involves integrating Smart Spaces with social networks through the IP Multimedia Subsystem. to create truly context-aware and adaptive spaces. By utilizing the wealth of user information present within social networks, smarter and more adaptive spaces can be created. We therefore propose the design and implementation of “SocioSpace” a Smart Spaces framework that utilizes the social context. We design and implement all components of SocioSpace, including the central server, the location management system, social network interfacing components, service delivery server and user agents. We then run various scenarios to test the reliability of the system. The results show the effectiveness of our framework in successfully creating Smart Spaces that can truly utilize social networks to deliver adaptive services that enhance the users’ experiences and make the environment more beneficial to them.     

E-science infrastructures for molecular modeling and parametrization

E-science infrastructures are becoming the essential tools for computational scientific research. In this paper, we describe two e-science infrastructures: Science and Engineering Applications Grid (SEAGrid) and molecular modeling and parametrization (ParamChem). The SEAGrid is a virtual organization with a diverse set of hardware and software resources and provides services to access such resources in a routine and transparent manner. These essential services include allocations of computational resources, client-side application interfaces, computational job and data management tools, and consulting activities. ParamChem is another e-science project dedicated for molecular force-field parametrization based on both ab-initio and molecular mechanics calculations on high performance computers (HPCs) driven by scientific workflow middleware services. Both the projects share a similar three-tier computational infrastructure that consists of a front-end client, a middleware web services layer, and a remote HPC computational layer. The client is a Java Swing desktop application with components for pre- and post-data processing, communications with middleware server and local data management. The middleware service is based on Axis2 web service and MySQL relational database, which provides functionalities for user authentication and session control, HPC resource information collections, discovery and matching, job information logging and notification. It can also be integrated with scientific workflow to manage computations on HPC resources. The grid credentials for accessing HPCs are delegated through MyProxy infrastructure. Currently SEAGrid has integrated several popular application software suites such as Gaussian for quantum chemistry, NAMD for molecular dynamics and engineering software such as Abacus for mechanical engineering. ParamChem has integrated CGenFF (CHARMM General Force-Field) for molecular force-field parametrization of drug-like molecules. Long-term storage of user data is handled by tertiary data archival mechanisms. SEAGrid science gateway serves more than 500 users while more than 1000 users use ParamChem services such as atom typing and initial force-field parameter guess at present.     

Revocable hierarchical identity-based encryption with shorter private keys and update keys

Revocable hierarchical identity-based encryption (RHIBE) is an extension of HIBE that supports the revocation of user’s private keys to manage the dynamic credentials of users in a system. Many different RHIBE schemes were proposed previously, but they are not efficient in terms of the private key size and the update key size since the depth of a hierarchical identity is included as a multiplicative factor. In this paper, we propose efficient RHIBE schemes with shorter private keys and update keys and small public parameters by removing this multiplicative factor. To achieve our goals, we first present a new HIBE scheme with the different generation of private keys such that a private key can be simply derived from a short intermediate private key. Next, we show that two efficient RHIBE schemes can be built by combining our HIBE scheme, an IBE scheme, and a tree based broadcast encryption scheme in a modular way.     

A suite of algorithms for key distribution and authentication in centralized secure multicast environments

The Extended Euclidean algorithm provides a fast solution to the problem of finding the greatest common divisor of two numbers. In this paper, we present three applications of the algorithm to the security and privacy field. The first one allows one to privately distribute a secret to a set of recipients with only one multicast communication. It can be used for rekeying purposes in a Secure Multicast scenario. The second one is an authentication mechanism to be used in environments in which a public-key infrastructure is not available. Finally, the third application of the Extended Euclidean algorithm is a zero-knowledge proof that reduces the number of messages between the two parts involved, with the aid of a central server.     

Differentially Private Significance Tests for Regression Coefficients

Many data producers seek to provide users access to confidential data without unduly compromising data subjects’ privacy and confidentiality. One general strategy is to require users to do analyses without seeing the confidential data; for example, analysts only get access to synthetic data or query systems that provide disclosure-protected outputs of statistical models. With synthetic data or redacted outputs, the analyst never really knows how much to trust the resulting findings. In particular, if the user did the same analysis on the confidential data, would regression coefficients of interest be statistically significant or not? We present algorithms for assessing this question that satisfy differential privacy. We describe conditions under which the algorithms should give accurate answers about statistical significance. We illustrate the properties of the proposed methods using artificial and genuine data. Supplementary materials for this article are available online.     

Authentication based on keystroke dynamics using stochastic diffusion algorithm

Authentication plays an important role in dealing with security. Securing sensitive data and computer systems by allowing easy access for authenticated users and withstanding the attacks of imposters is one of the major challenges in the field of computer security. Nowadays, passwords have become the trend to control access to computer systems. Biometrics are used to measure and analyze an individual's unique behavioral or physiological patterns for authentication purposes. Keystroke dynamics have emerged as an important method in analyzing the typing rhythm in biometric techniques, as they provide an ease of use and increased trustworthiness associated with biometrics for creating username and password schemes. In this experiment, we measure the Hausdorff timing values, mean, standard deviation, and median of keystroke features, such as latency, duration, digraph, and their combinations, and compare their performance. The stochastic diffusion search is used for feature subset selection.     

Design of Self-Healing Key Distribution Schemes

A self-healing key distribution scheme enables dynamic groups of users of an unreliable network to establish group keys for secure communication. In such a scheme, a group manager, at the beginning of each session, in order to provide a key to each member of the group, sends packets over a broadcast channel. Every user, belonging to the group, computes the group key by using the packets and some private information. The group manager can start multiple sessions during a certain time-interval, by adding/removing users to/from the initial group. The main property of the scheme is that, if during a certain session some broadcasted packet gets lost, then users are still capable of recovering the group key for that session simply by using the packets they have received during a previous session and the packets they will receive at the beginning of a subsequent one, without requesting additional transmission from the group manager. Indeed, the only requirement that must be satisfied, in order for the user to recover the lost keys, is membership in the group both before and after the sessions in which the broadcast messages containing the keys are sent. This novel and appealing approach to key distribution is quite suitable in certain military applications and in several Internet-related settings, where high security requirements need to be satisfied. In this paper we continue the study of self-healing key distribution schemes, introduced by Staddon et al. [37]. We analyze some existing constructions: we show an attack that can be applied to one of these constructions, in order to recover session keys, and two problems in another construction. Then, we present a new mechanism for implementing the self-healing approach, and we present an efficient construction which is optimal in terms of user memory storage. Finally, we extend the self-healing approach to key distribution, and we present a scheme which enables a user to recover from a single broadcast message all keys associated with sessions in which he is member of the communication group.