A secure outsourced Turing- equivalent computation scheme against semi-honest workers using fully homomorphic encryption

A scheme that can realize homomorphic Turing- equivalent privacy-preserving computations is proposed, where the encoding of the Turing machine is independent of its inputs and running time. Several extended private information retrieval protocols based on fully homomorphic encryption are designed, so that the reading and writing of the tape of the Turing machine, as well as the evaluation of the transition function of the Turing machine, can be performed by the permitted Boolean circuits of fully homomorphic encryption schemes. This scheme overwhelms the Turing-machine-to- circuit conversion approach, which also implements the Turing-equivalent computation. The encoding of a Turing- machine-to-circuit conversion approach is dependent on both the input data and the worst-case runtime. The proposed scheme efficiently provides the confidentiality of both program and data of the delegator in the delegator-worker model of outsourced computation against semi-honest workers.

CExp： secure and verifiable outsourcing of composite modular exponentiation with single untrusted server

Outsnurcing computing allows users with resource-constrained devices tn outsnurce their complex computation wnrkloads to cloud servers that may not be honest. In this paper, we propose a new algorithm for securing the outsourcing of composite modnlar exponentiation, which is one of the most complex computing tasks in discrete- log based cryptographic protocols. Unlike algorithms based on two untrusted servers, we outsnurce modular expnnentiation operation to only a single server, which eliminates the potential for a cnllusinn attack when using two servers. Moreover, our proposed algorithm can hide the base and exponent of the outsourced data, which prevents the exposure of sensitive information to clnud servers. In addition, compared with the state-of-the-art algorithms, our scheme has remarkably better checkability, The user could detect any misbehavior with a probability of one if the server returns a fault result.

Achieving reliable and anti-collusive outsourcing computation and verification based on blockchain in 5G-enabled IoT

Widespread applications of 5G technology have prompted the outsourcing of computation dominated by the Internet of Things(IoT)cloud to improve transmission efficiency,which has created a novel paradigm for improving the speed of common connected objects in IoT.However,although it makes it easier for ubiquitous resource-constrained equipment that outsources computing tasks to achieve high-speed transmission services,security concerns,such as a lack of reliability and collusion attacks,still exist in the outsourcing computation.In this paper,we propose a reliable,anti-collusion outsourcing computation and verification protocol,which uses distributed storage solutions in response to the issue of centralized storage,leverages homomorphic encryption to deal with outsourcing computation and ensures data privacy.Moreover,we embed outsourcing computation results and a novel polynomial factorization algorithm into the smart contract of Ethereum,which not only enables the verification of the outsourcing result without a trusted third party but also resists collusion attacks.The results of the theoretical analysis and experimental performance evaluation demonstrate that the proposed protocol is secure,reliable,and more effective compared with state-of-the-art approaches.

A potential game-based outsourcing computation framework for multiple calculators

Outsourcing computation enables a computationally weak client to outsource the computation of a function f to a more powerful but untrusted server.The traditional outsourcing computation model forbids communication between players,but it has little effect.Based on the game theory,this paper establishes an outsourcing computation model which is more in line with the actual scene.Firstly,we construct a structural mapping relationship between security outsourcing computation and the optimization problem.Secondly,by designing the individual potential function and the global potential function,the individual goal is consistent with the global goal to ensure the correctness of the calculation results.Finally,in the information exchange environment between calculators,we construct a Zero-determinant strategy to ensure that the calculator chooses the strategy according to the predetermined target.

Blockchain-Based Light-Weighted Provable Data Possession for Low Performance Devices

Provable Data Possession(PDP)schemes have long been proposed to solve problem of how to check the integrity of data stored in cloud service without downloading.However,with the emerging of network consisting of low performance devices such as Internet of Things,we find that there are still two obstacles for applying PDP schemes.The first one is the heavy computation overhead in generating tags for data blocks,which is essential for setting up any PDP scheme.The other one is how to resist collusion attacks from third party auditors with any possible entities participating the auditing.In this paper,we propose a novel blockchain-based light-weighted PDP scheme for low performance devices,with an instance deployed on a cloud server.We design a secure outsourced tag generating method for low performance devices,which enables a kind of“hash-sign-switch”two-phase tag computing.With this method,users with low performance devices can employ third party auditors to compute modular exponential operations that accounts for the largest portion of computation overhead in tag generation,without leaking their data content.Chaincodes in blockchain network ensure the correctness of such outsourcing and prevent collusion attacks.The security analysis and performance evaluation prove that our scheme is both secure and efficient.

SEOT: Secure dynamic searchable encryption with outsourced ownership transfer

When one enterprise acquires another,the electronic data of the acquired enterprise will be transferred to the acquiring enterprise.In particular,if the data system of acquired enterprise contains a searchable encryption mechanism,the corresponding searchability will also be transferred.In this paper,we introduce the concept of Searchable Encryption with Ownership Transfer(SEOT),and propose a secure SEOT scheme.Based on the new structure of polling pool,our proposed searchable encryption scheme not only achieves efficient transfer of outsourced data,but also implements secure transfer of data searchability.Moreover,we optimize the storage cost for user to a desirable value.We prove our scheme can achieve the secure characteristics,then carry out the performance evaluation and experiments.The results demonstrate that our scheme is superior in efficiency and practicability.

Lightning-fast and privacy-preserving outsourced computation in the cloud

In this paper,we propose a framework for lightning-fast privacy-preserving outsourced computation framework in the cloud,which we refer to as LightCom.Using LightCom,a user can securely achieve the outsource data storage and fast,secure data processing in a single cloud server different from the existing multi-server outsourced computation model.Specifically,we first present a general secure computation framework for LightCom under the cloud server equipped with multiple Trusted Processing Units(TPUs),which face the side-channel attack.Under the LightCom,we design two specified fast processing toolkits,which allow the user to achieve the commonly-used secure integer computation and secure floating-point computation against the side-channel information leakage of TPUs,respectively.Furthermore,our LightCom can also guarantee access pattern protection during the data processing and achieve private user information retrieve after the computation.We prove that the proposed LightCom can successfully achieve the goal of single cloud outsourced data processing to avoid the extra computation server and trusted computation server,and demonstrate the utility and the efficiency of LightCom using simulations.

Verifiable Auditing Protocol with Proxy Re-Encryption for Outsourced Databases in Cloud

As a new computing paradigm, outsourcing computing provides inexpensive, on-demand, convenient storage and computing services for cloud clients. For the security of outsourcing databases to the cloud, it is important to allow the user to verify the query results returned by the cloud server. So far, tremendous efforts have been carried out to study secure outsourcing computing. The existing scheme supports that the user can detect the correctness and completeness of the query results even if the cloud server returns an empty set. However, since the data owner performs the database encryption operations and uploads the encrypted database to the cloud server, they require the user to request the data owner to decrypt the query results. In this paper, we propose a new scheme, which can accurately verify the search results. Meanwhile, the users can decrypt the query results independently. Furthermore, the proposed scheme supports a large number of data owners to upload their encrypted database to the cloud server, and it can efficiently verify the query results. Besides, we can prove that our proposed solution can achieve the desired security properties.

Lightning-fast and privacy-preserving outsourced computation in the cloud

In this paper,we propose a framework for lightning-fast privacy-preserving outsourced computation framework in the cloud,which we refer to as LightCom.Using LightCom,a user can securely achieve the outsource data storage and fast,secure data processing in a single cloud server different from the existing multi-server outsourced computation model.Specifically,we first present a general secure computation framework for LightCom under the cloud server equipped with multiple Trusted Processing Units(TPUs),which face the side-channel attack.Under the LightCom,we design two specified fast processing toolkits,which allow the user to achieve the commonly-used secure integer computation and secure floating-point computation against the side-channel information leakage of TPUs,respectively.Furthermore,our LightCom can also guarantee access pattern protection during the data processing and achieve private user information retrieve after the computation.We prove that the proposed LightCom can successfully achieve the goal of single cloud outsourced data processing to avoid the extra computation server and trusted computation server,and demonstrate the utility and the efficiency of LightCom using simulations.

Flexible CP-ABE Based Access Control on Encrypted Data for Mobile Users in Hybrid Cloud System

In hybrid cloud computing, encrypted data access control can provide a fine-grained access method for organizations to enact policies closer to organizational policies. This paper presents an improved CP-ABE (ciphertext-policy attribute-based encryption) scheme to construct an encrypted data access control solution that is suitable for mobile users in hybrid cloud system. In our improvement, we split the original decryption keys into a control key, a secret key and a set of transformation keys. The private cloud managed by the organization administrator takes charge of updating the transformation keys using the control key. It helps to handle the situation of flexible access management and attribute alteration. Meanwhile, the mobile user's single secret key remains unchanged as well as the ciphertext even if the data user's attribute has been revoked. In addition, we modify the access control list through adding the attributes with corresponding control key and transformation keys so as to manage user privileges depending upon the system version. Finally, the analysis shows that our scheme is secure, flexible and efficient to be applied in mobile hybrid cloud computing.