A new revocable and re-delegable proxy signature and its application

With the popularity of cloud computing and mobile Apps, on-demand services such as on-line music or audio streaming and vehicle booking are widely available nowadays. In order to allow efficient delivery and management of the services, for large-scale on-demand systems, there is usually a hierarchy where the service provider can delegate its service to a top-tier (e.g., countrywide) proxy who can then further delegate the service to lower level (e.g., region-wide) proxies. Secure (re-)delegation and revocation are among the most crucial factors for such systems. In this paper, we investigate the practical solutions for achieving re-delegation and revocation utilizing proxy signature. Although proxy signature has been extensively studied in the literature, no previous solution can achieve both properties. To fill the gap, we introduce the notion of revocable and re-delegable proxy signature that supports efficient revocation and allows a proxy signer to re-delegate its signing right to other proxy signers without the interaction with the original signer. We define the formal security models for this new primitive and present an efficient scheme that can achieve all the security properties. We also present a secure on-line revocable and re-delegate vehicle ordering system (RRVOS) as one of the applications of our proposed scheme

A secure IoT cloud storage system with fine-grained access control and decryption key exposure resistance

Internet of Things (IoT) cloud provides a practical and scalable solution to accommodate the data management in large-scale IoT systems by migrating the data storage and management tasks to cloud service providers (CSPs). However, there also exist many data security and privacy issues that must be well addressed in order to allow the wide adoption of the approach. To protect data confidentiality, attribute-based cryptosystems have been proposed to provide fine-grained access control over encrypted data in IoT cloud. Unfortunately, the existing attributed-based solutions are still insufficient in addressing some challenging security problems, especially when dealing with compromised or leaked user secret keys due to different reasons. In this paper, we present a practical attribute-based access control system for IoT cloud by introducing an efficient revocable attribute-based encryption scheme that permits the data owner to efficiently manage the credentials of data users. Our proposed system can efficiently deal with both secret key revocation for corrupted users and accidental decryption key exposure for honest users. We analyze the security of our scheme with formal proofs, and demonstrate the high performance of the proposed system via experiments

Mergeable and revocable identity-based encryption

Identity-based encryption (IBE) has been extensively studied and widely used in various applications since Boneh and Franklin proposed the first practical scheme based on pairing. In that seminal work, it has also been pointed out that providing an efficient revocation mechanism for IBE is essential. Hence, revocable identity-based encryption (RIBE) has been proposed in the literature to offer an efficient revocation mechanism. In contrast to revocation, another issue that will also occur in practice is to combine two or multiple IBE systems into one system, e.g., due to the merge of the departments or companies. However, this issue has not been formally studied in the literature and the naive solution of creating a completely new system is inefficient. In order to efficiently address this problem, in this paper we propose the notion of mergeable and revocable identity-based encryption (MRIBE). Our scheme provides the first solution to efficiently revoke users and merge multiple IBE systems into a single system. The proposed scheme also has several nice features: when two systems are merged, there is no secure channel needed for the purpose of updating user private keys; and the size of the user private key remains unchanged when multiple systems are merged. We also propose a new security model for MRIBE, which is an extension of the security model for RIBE, and prove that the proposed scheme is semantically secure without random oracles

The Improvement of 3D Traveltime Tomographic Inversion Method

As 3D high-precision seismic exploration is more and more widely used in seismic data acquisition, traveltime tomographic inversion based on first arrivals is developed from 2D to 3D. However, magnanimity data of 3D traveltime inversion brings about the problem of data storage; the absence of first arrivals with near offset reduces the precision of shallow layer; the utilization of prior information, such as small refraction and micro-logging data, can improve the precision of 3D traveltime inversion. Therefore, we make some improvements in 3D traveltime inversion method. We take compression storage for large and sparse matrix, propose virtual receivers technology, and add prior information to tomographic inversion linear equations. The application in 3D real data indicates that the improvements can effectively improve 3D traveltime tomographic inversion.Key words: 3D seismic exploration; 3D traveltime inversion method; 3D traveltime tomographic inversio