Constant-size threshold attribute based SignCryption for cloud applications

In this paper, we propose a novel constant-size threshold attribute-based signcryption scheme for securely sharing data through public clouds. Our proposal has several advantages. First, it provides flexible cryptographic access control, while preserving users’ privacy as the identifying information for satisfying the access control policy are not revealed. Second, the proposed scheme guarantees both data origin authentication and anonymity thanks to the novel use of attribute based signcryption mechanism, while ensuring the unlinkability between the different access sessions. Third, the proposed signcryption scheme has efficient computation cost and constant communication overhead whatever the number of involved attributes. Finally, our scheme satisfies strong security properties in the random oracle model, namely Indistinguishability against the Adaptive Chosen Ciphertext Attacks (IND-CCA2), Existential Unforgeability against Chosen Message Attacks (EUFCMA) and privacy preservation of the attributes involved in the signcryption process, based on the assumption that the augmented Multi-Sequence of Exponents Decisional Diffie-Hellman (aMSE-DDH) problem and the Computational Diffie Hellman Assumption (CDH) are hard

Cloud Security in Crypt Database Server Using Fine Grained Access Control

Information sharing in the cloud, powered by good patterns in cloud technology, is rising as a guaranteeing procedure for permitting users to advantageously access information. However, the growing number of enterprises and customers who stores their information in cloud servers is progressively challenging users’ privacy and the security of information. This paper concentrates on providing a dependable and secure cloud information sharing services that permits users dynamic access to their information. In order to achieve this, propose an effective, adaptable and flexible privacy preserving information policy with semantic security, by using Cipher text Policy Element Based Encryption (CP-EBE) consolidated with Character Based Encryption (CBE) systems. To ensure strong information sharing security, the policy succeeds in protecting the privacy of cloud users and supports efficient and secure dynamic operations, but not constrained to, file creation, user revocation. Security analysis demonstrates that the proposed policy is secure under the generic bi- linear group model in the random oracle model and enforces fine-grained access control, full collusion resistance and retrogressive secrecy. Furthermore, performance analysis and experimental results demonstrate that the overheads are as light as possible

MICSIM : Concept, Developments and Applications of a PC-Microsimulation Model for Research and Teaching

It is the growing societal interest about the individual and its behaviour in our and 'modern' societies which is asking for microanalyses about the individual situation. In order to allow these microanalyses on a quantitative and empirically based level microsimulation models were developed and increasingly used for economic and social policy impact analyses. Though microsimulation is known and applied (mainly by experts), an easy to use and powerful PC microsimulation model is hard to find. The overall aim of this study and of MICSIM - A PC Microsimulation Model is to describe and offer such a user-friendly and powerful general microsimulation model for (almost) any PC, to support the impact microanalyses both in applied research and teaching. Above all, MICSIM is a general microdata handler for a wide range of typical microanalysis requirements. This paper presents the concept, developments and applications of MICSIM. After some brief remarks on microsimulation characteristics in general, the concept and substantive domains of MICSIM: the simulation, the adjustment and aging, and the evaluation of microdata, are described by its mode of operation in principle. The realisations and developments of MICSIM then are portrayed by the different versions of the computer program. Some MICSIM applications and experiences in research and teaching are following with concluding remarks.Economic and Social Policy Analyses, Microsimulation (dynamic and static), Simulation, Adjustment and Evaluation of Microdata, PC Computer Program for Microanalyses in General