The development of E-commerce platforms has provided convenience for consumers, and many shopping platforms advertise products to users based on their preferences. However, this kind of recommendation, based on historical browsing or purchase data, can infer user behavior, which threatens user privacy. Encrypted browsing or purchase data protects user privacy but blinds the server from making recommendations. We have improved the algorithm (GPKE-MET) based on equivalence testing for public key encryption to support batch testing, which can be applied to large-scale encrypted data processing on E-commerce platforms. In addition,GPKE-METis against guessing by the attackers (i.e., malicious cloud server) for the predictable information so as to enhance the data privacy. Therefore, with the help ofGPKE-MET, the E-commerce platform can make product recommendations effectively, although the underlying data is encrypted.

Secure deduplication not only optimizes cloud storage but also prevents data leakage. However, traditional schemes are with high computation and communication costs to deal with large-scale multimedia data. To address this problem, we propose a fog computing-based fuzzy deduplication (HDeFC), a two-stage privacy-preserving deduplication protocol. Our approach prevents guessing attacks and single point of failure, besides that also implements noninteractive Proof of Ownership and label consistency verification. In addition, we also achieve the access permission for only legitimate users. Our performance evaluation shows that the hierarchical setting is efficient in deduplication.

Cloud storage technology is constantly evolving, resulting in a significant amount of duplicate data being stored in the cloud, particularly multimedia data such as images and videos. In terms of data privacy and storage optimization, the encrypted deduplication should be checked to save space overhead for cloud servers. Compared to exact deduplication, fuzzy deduplication is low-cost for encrypted multimedia data. Focusing on reducing the false deletion rate, an efficient and secure fuzzy deduplication system based on dual-feature without additional servers is proposed. We also propose a concept of pre-verification for label consistency to compensate for the loss that cannot be fixed through post-verification. Therefore, it is more practical. Finally, we conduct experiments on real-world datasets for performance evaluation. The experimental results show good performance in terms of both computational cost and deduplication efficiency.

In the last few years, mobile cloud computing (MCC) gains a huge development because of the popularity of mobile applications and cloud computing. User authentication and access control are two indispensable security components in the MCC environment. To the best of our knowledge, they are generally designed in different procedures. Access control can be executed after the authentication completes successfully. In order to improve efficiency, this article constructs an integrated scheme of authentication and hierarchical access control using self-certified public key cryptography (SCPKC) and the Chinese remainder theorem (CRT) for MCC environment. The proposed scheme can achieve mutual authentication while determining the access rights of mobile users without storing any access control list in the MCC service provider side. Besides, we also give a dynamic adding or deletion of MCC service provider to efficiently address potential changes in the hierarchy. The security of our proposed scheme is proved by the random oracle model. Compared with recently related multi-server authentication schemes for the MCC environment, the proposed scheme not only adds a new function of hierarchical access control but also has better computation and communication efficiencies. Therefore, the proposed scheme is more suitable for real-life MCC applications.

The multiserver architecture authentication (MSAA) protocol plays a significant role in achieving secure communications between devices. In recent years, researchers proposed many new MSAA protocols to gain more functionality and security. However, in the existing studies, registered users can access to all registered service providers in the system without any limitation. To ensure that the system can restrict users that are at different levels and can access to different levels of service providers, we propose a new lightweight hierarchical authentication protocol for multiserver architecture using a Merkle tree to verify user’s authentication right. The proposed protocol has hierarchical authentication functionality, high security, and reasonable computation and communication costs. Moreover, the security analysis demonstrates that the proposed protocol satisfies the security requirements in practical applications, and the proposed protocol is provably secure in the general security model.

With the popularity of the Internet, the load on the servers is aggravated heavily, so secret sharing is used as a fundamental approach for improving availability of an online service. In a (t, n)-threshold secret sharing scheme, any t-out-of-n participants could recover the shared secret, and any less than t participants could get nothing about the shared secret. However, with the long life of the secret, the number of adversaries increase over time. In order to deal with this issue, one may require to increase the threshold value from t to t'(t' > t). In the traditional, existing Threshold Changeable Secret Sharing(TCSS) schemes either required secure channel or no security analysis. Motivated by that, we propose a new practice-oriented TCSS scheme using partial broadcast channel(PBC) in both share distribution phase and secret reconstruction phase. Our protocol increases the dealer and the combiner's communication rate and resist to collusion attack. Furthermore it is an ideal and robust threshold scheme which threshold parameters are likely to happen several times. Therefore our protocol is practice-oriented scheme.

This correspondence points out an important error of calculating the detection probability in a recent paper by Jiankui et al. (2008). The authors make a mistake in the analysis of the distribution of the detector statistic. Therefore, the calculation of the detection probability is wrong. In this correspondence, a new detection probability is calculated.

Self-healing key distribution schemes are particularly useful when there is no network infrastructure or such infrastructure has been destroyed. A self-healing mechanism can allow group users to recover lost session keys and is therefore quite suitable for establishing group keys over an unreliable network, especially for infrastructureless wireless networks, where broadcast messages loss may occur frequently. An efficient threshold self-healing key distribution scheme with favorable properties is proposed in this paper. Firstly, the distance between two broadcasts used to recover the lost one is alterable according to network conditions. This alterable property can be used to shorten the length of the broadcast messages. Secondly, any more than threshold-value users can sponsor a new user to join the group for the subsequent sessions without any interaction with the group manager. Thirdly, the storage overhead of the self-healing key distribution at each group user is a polynomial over a finite field, which will not increase with the number of sessions. In addition, if a smaller group of users up to a threshold-value were revoked, the personal keys for non-revoked users can be reused.

The members in the dynamic peer group (DPG) are divided into several clusters according to linker cluster architecture (J.B. Dennis and E. Anthony, 1981). In each cluster, the members perform the BD protocol (M. Burmester and Y. Desmedt, 1994) to establish the cluster key and the TGDH protocol (Y. Kim et al., 2004) is performed among the clusters to generate the group key. This method can not only avoid the weakness of AKA (auxiliary key agreement) of BD, but also reduce the computation cost of TGDH scheme. In our scheme the members have been authenticated based identity, and we prove the security in random oracle model.

Recently, Chien [1] proposed a time-bound hierarchical key assignment scheme based on tamper-resistant devices. Chein's scheme greatly reduces computation load and implementation cost. However, it has a security weakness against X. Yi's three-party collusion attack [2]. In this paper, we improved Chien's scheme without public key cryptography and our scheme is resistant to X. Yi's three-party collusion attack. The most important is that our scheme is as efficient as Chein's. Finally, we have made an experiment to verify our conclusion.