A note on the bound for the class of certain nilpotent groups

Assume G is a nilpotent group of class > 3 in which every proper subgroup has class at most 3. In this note, we give the exact upper bound of class of G

Public Key Encryption Supporting Equality Test and Flexible Authorization without Bilinear Pairings

In recent years, public key encryption with equality test (PKEET) has become a hot research topic in the cryptography community due to the advancement of cloud computing. Recently, Ma et al. proposed a new related primitive, called public key encryption with equality test supporting flexible authorization (PKEET-FA), and constructed a concrete scheme. In their proposal, four types of authorization were presented to support different authorization policies. However, their proposal is based on bilinear pairings which are time costing operations compared with modular exponentiations. In this paper, we present a new PKEET-FA scheme without bilinear pairings. Compared with the existing work, our proposal is more efficient

New Efficient and Flexible Algorithms for Secure Outsourcing of Bilinear Pairings

Outsourcing paradigm has become a hot research topic in the cryptography community, where computation workloads can be outsourced to cloud servers by the resource-constrained devices, such as RFID tags. The computation of bilinear pairings is the most expensive operation in pairing-based cryptographic primitives. In this paper, we present two new algorithms for secure outsourcing the computation of bilinear pairings. One is secure in the OMTUP model. The other, which provides flexible checkability, is in the TUP model. Compared with the state-of-the-art algorithms, our proposal is more efficient

EmoCo: Visual analysis of emotion coherence in presentation videos

Emotions play a key role in human communication and public presentations. Human emotions are usually expressed through multiple modalities. Therefore, exploring multimodal emotions and their coherence is of great value for understanding emotional expressions in presentations and improving presentation skills. However, manually watching and studying presentation videos is often tedious and time-consuming. There is a lack of tool support to help conduct an efficient and in-depth multi-level analysis. Thus, in this paper, we introduce EmoCo, an interactive visual analytics system to facilitate efficient analysis of emotion coherence across facial, text, and audio modalities in presentation videos. Our visualization system features a channel coherence view and a sentence clustering view that together enable users to obtain a quick overview of emotion coherence and its temporal evolution. In addition, a detail view and word view enable detailed exploration and comparison from the sentence level and word level, respectively. We thoroughly evaluate the proposed system and visualization techniques through two usage scenarios based on TED Talk videos and interviews with two domain experts. The results demonstrate the effectiveness of our system in gaining insights into emotion coherence in presentations.Comment: 11 pages, 8 figures. Accepted by IEEE VAST 201

Cryptanalysis of A Privacy-Preserving Smart Metering Scheme Using Linkable Anonymous Credential

To accomplish effective privacy protection in smart grid systems, various approaches were proposed combining information security technology with the smart grid\u27s new features. Diao et al. proposed a privacy-preserving scheme using linkable anonymous credential based on CL signature, and demonstrated its identity anonymity, message authentication and traceability of broken smart meters. In this paper, a forgery attack is presented to point out the protocol dissatisfies message authentication and unforgeability. We hold the idea that this scheme doesn\u27t have basic safety requirements and application value

New Approaches for Secure Outsourcing Algorithm for Modular Exponentiations

Outsourcing paradigm is one of the most attractive benefits of cloud computing, where computation workloads can be outsourced to cloud servers by the resource-constrained devices, such as RFID tags. With this paradigm, cloud users can avoid setting up their own infrastructures. As a result, some new challenges, such as security and checkability, are inevitably introduced. In this paper, we address the problem of secure outsourcing algorithm for modular exponentiations in the one-malicious version of two untrusted program model. We show that our proposed algorithm is more efficient than the state-of-the-art algorithms. On the other hand, we point out in this paper that the first outsource-secure algorithm for simultaneous modular exponentiations proposed recently is insecure, where the sensitive information can be leaked to the malicious servers. As a result, we propose a new and more efficient algorithm for simultaneous modular exponentiations. We also propose the constructions for outsource-secure Cramer-Shoup encryptions and Schnorr signatures which are also more efficient than the state-of-the-art algorithms