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In application scenarios such as cloud storage, a symmetric algorithm can be used to encrypt massive data. However, using the symmetric operation and keys in encryption and decryption, it is very difficult to realize an efficient access control system. The asymmetric encryption algorithm ciphertext-policy attribute-based encryption (CP-ABE), as a versatile one-to-many encryption algorithm, is considered an ideal access control tool to solve the user's distrust of the service provider of cloud storage. However, in a traditional CP-ABE system, the malicious users may deliberately leak their attribute keys to others or build a decryption black box (DB) to provide illegal decryption services for benefits, while no one can determine their identities. To deal with the problems, especially the problem of tracing the DB builder, CP-ABE schemes with black-box traceability have been proposed in the past few years. But in this paper, we point out that for now, the tracing algorithms in all existing schemes actually work on an impractical assumption. That is, whenever a DB receives a decryption request, it always performs the decryption algorithm honestlycorrectly. We argue that if a DB finds the decryption request comes from the tracing algorithm, it may intentionally output incorrect decryption results to counter the tracing. Thus, we present the structural defect of the tracing algorithm applied to all known traceable CP-ABE schemes. We describe the construction of an alert decryption black box (ADB) that is capable of distinguishing a tracing ciphertext from a normal one. We also show how an ADB frustrates the tracing algorithm, and furthermore, malicious users can even apply an ADB to frame innocent users. [ABSTRACT FROM AUTHOR]

ABE scheme has been more and more widely used in cloud storage,it can achieve fine-granularity access control. However, most of the existing ABE schemes have the problems of low efficiency and high overhead. In order to solve this problem, this paper proposed a more efficient and fine-grained attribute-based encryption scheme supporting attribute revocation. The transfers the complex computation of the encryption and decryption process to the proxy server, thus reducing the encryption and decryption computation of users. This paper also proposed an efficient attribute revocation method which concentrated on the update of the ciphertexts and users' secret keys associated with the corresponding revoked attributes, so the cost of attribute revocation is very small . And combined the method of two-factor identity authentication to improve the security of the algorithm. The theoretical analysis show that this scheme is safe under the standard model based on the DBDH hypothesis. [ABSTRACT FROM AUTHOR]

Dispatching and Control Cloud (DCC) is a cloud platform constructed by State Grid Corporation with the technology of cloud computing. DCC has improved the overall operation and monitoring capabilities, the smart level and many other advantages of power grid. However, the development of DCC has been hampered by security and privacy issues. Secure unified identity authentication, access control and authorisation management are significant topics in DCC. To find out a solution for the topics above, we have employed some encryption schemes using the attribute-based encryption(ABE), as ABE can preserve users' privacy and achieve access control with fine grain over the encrypted information. SM9 is a kind of Chinese official standard in the field of cryptography, which contains the SM9 encryption algorithm (SM9-IBE). In this paper, an ABE scheme based on SM9-IBE is proposed, making SM9 support fine-grained access control which would be better applied in DCC. Our proposed scheme (SM9-ABE) has been proven to be of great security in the selective CPA model under DBDH assumption. Furthermore, we implement SM9-ABE and evaluate its practical performance. The implementation indicates our scheme performs well in the matter of security and functionality, at an additional time cost which is acceptable. [ABSTRACT FROM AUTHOR]

The Big Data stored in the cloud-based clusters of nodes requires an efficient mechanism to protect its privacy information. The traditional anonymization approach for privacy preservation is not applicable for Big Data due to overheads induced as the data storage mechanism follows a distributed file system in the cloud eco-store. This paper presents a dual-layer security model that mitigates the attackers' effect on access to private information. The model architecture consists of a strong authentication mechanism where the key generation to get the access control adopts a high random and customization policy so that at first hand the intruder's probability of entering into the cloud system is nullified and effectively handles the anonymity attack, in the second part of the security model the privacy information part of the data is encrypted with a very lightweight encryption method, and it gets synchronized with the data-deduplication template of the data nodes in the cloud so that the proposed model provides higher security of the privacy information in less time complexities of the cryptographic algorithm which makes the models more reliable as well as flexible to adopt it in the real-time scenario. The behavioral analysis of the proposed Auth-PP for the file-token generation system becomes stable with the incremental file size and exhibits a consistency measure (Ct) = 0.56, which is a mean orient pattern that shows strong stability against the file size so quite adaptable for the big data. The computational performance analysis for cost assessment of encryption and decryption process shows 72% performance improvement for running time for variable file sizes and also exhibits the superior outcome of overall 69.9% for file chunking into the data node on the respective cloud. For the decryption process also, it is observed that the formulated approach attains superior performance in terms of time complexity. [ABSTRACT FROM AUTHOR]

Storing only one unique copy of the same cloud data and guaranteeing its integrity are two main goals for cloud storage auditing and deduplication schemes. In such schemes, data owners can firmly believe the data integrity by periodically auditing and the cloud server can save lots of storage space by exploiting the duplication techniques. However, when a data owner deletes or modifies his outsourced data, he should lose the ownership for the original data and should not be able to successfully retrieve this data any more. For all we know, existing cloud storage auditing and deduplication literatures fail to support the modifications of ownership, which actually occur quite often in actual cloud storage scenarios. In this paper, we propose the first deduplicated data integrity auditing scheme supporting the ownership modification. It guarantees the integrity of the outsourced data and supports the dynamic access control over the outsourced data. We employ a re-encryption algorithm and the secure identity-based broadcast encryption technology, which prevent data from being disclosed to the revoked owners, even if they previously had prior ownership of these data. The security and efficiency of our proposed scheme have been validated by detailed analysis and experiments. [ABSTRACT FROM AUTHOR]

Data security is of utmost importance these days due to widespread usage of cloud environment for storage of data. As the data is stored in chunks in multiple location servers, it is quite difficult to manage the access control and privacy. Being significant to any stream, data security has gained immense popularity in research. Cryptography plays a vital role in preserving data confidentiality from unauthorized access and intruders. Though this area is researched a lot but new cryptographic schemes are introduced frequently to upgrade the level of security. In this paper we review some of the most popular cryptographic mechanisms used in data storage environment, especially in cloud to protect privacy and integrity of data. We finally compare efficiency of algorithms with respect to operational time consumption. Simulation results demonstrates the comparative performance of symmetric, asymmetric algorithms and hashing mechanisms among the peers. [ABSTRACT FROM AUTHOR]