基于层次结构的隐私多维分析查询算法

基于本地化差分隐私的多维分析查询(multi-dimensional analytical query,MDA)已得到了研究者的广泛关注.现有基于最优局部哈希(optimal local Hashing,OLH)机制与层次树结构的扰动方法存在泄露根结点隐私的风险.针对现有结合层次树结构的本地扰动机制不足,提出了一种有效且满足本地化差分隐私的MDA查询算法H4MDA (hierarchical structure for MDA),该算法充分利用层次树的横向与纵向结构特征设计了3种基于用户分组策略的本地扰动算法HGRR,LGRR-FD,LGRR.算法HGRR结合层次树横向结构与GRR机制本地扰动用户元组数据,通过摈弃根结点组合来响应MDA查询.不同于HGRR,LGRR-FD算法利用层次树的纵向结构与GRR机制扰动本地数据,同时通过添加假数据来避免叶子结点的隐私泄露.LGRR算法通过摈弃叶子结点层纵向扰动本地数据.收集者结合LGRR的扰动结果利用局部一致性处理技术重构层次树最后两层,通过添加虚拟叶子结点来响应MDA查询,而虚拟叶子结点计数之和等于其父节点计数.HGRR,LGRR-FD,LGRR算法与现有扰动算法在3种数据集上实验结果表明,其响应MDA查询的精度优于同类算法.

Improved conditional differential attacks on lightweight hash family QUARK

Nonlinear feedback shift register(NFSR)is one of the most important cryptographic primitives in lightweight cryptography.At ASIACRYPT 2010,Knellwolf et al.proposed conditional differential attack to perform a cryptanalysis on NFSR-based cryptosystems.The main idea of conditional differential attack is to restrain the propagation of the difference and obtain a detectable bias of the difference of the output bit.QUARK is a lightweight hash function family which is designed by Aumasson et al.at CHES 2010.Then the extended version of QUARK was published in Journal of Cryptology 2013.In this paper,we propose an improved conditional differential attack on QUARK.One improvement is that we propose a method to select the input difference.We could obtain a set of good input differences by this method.Another improvement is that we propose an automatic condition imposing algorithm to deal with the complicated conditions efficiently and easily.It is shown that with the improved conditional differential attack on QUARK,we can detect the bias of output difference at a higher round of QUARK.Compared to the current literature,we find a distinguisher of U-QUARK/D-QUARK/S-QUARK/C-QUARK up to 157/171/292/460 rounds with increasing 2/5/33/8 rounds respectively.We have performed the attacks on each instance of QUARK on a 3.30 GHz Intel Core i5 CPU,and all these attacks take practical complexities which have been fully verified by our experiments.As far as we know,all of these results have been the best thus far.

Searching for impossible subspace trails and improved impossible differential characteristics for SIMON-like block ciphers

In this paper,we greatly increase the number of impossible differentials for SIMON and SIMECK by eliminating the 1-bit constraint in input/output difference,which is the precondition to ameliorate the complexity of attacks.We propose an algorithm which can greatly reduce the searching complexity to find such trails efficiently since the search space exponentially expands to find impossible differentials with multiple active bits.There is another situation leading to the contradiction in impossible differentials except for miss-in-the-middle.We show how the contradiction happens and conclude the precondition of it defined as miss-from-the-middle.It makes our results more comprehensive by applying these two approach simultaneously.This paper gives for the first time impossible differential characteristics with multiple active bits for SIMON and SIMECK,leading to a great increase in the number.The results can be verified not only by covering the state-of-art,but also by the MILP model.

A new encryption scheme for surveillance videos

In this paper, we propose a novel framework to encrypt surveillance videos. Although a few encryption schemes have been proposed in the literature, they are not sufficiently efficient due to the lack of full consideration of the characteristics of surveillance videos, i.e., intensive global redundancy. By taking advantage of such redundancy, we design a novel method for encrypting such videos. We first train a background dictionary based on several frame observations. Then every single frame is parsed into the background and foreground components. Separation is the key to improve the efficiency of the proposed technique, since encryption is only carried out in the foreground, while the background is skillfully recorded by corresponding background recovery coefficients. Experimental results demonstrate that, compared to the state of the art, the proposed method is robust to known cryptanalytic attacks, and enhances the overall security due to the foreground and background separation. Additionally, our encryption method is faster than competing methods, which do not conduct foreground extraction.

Unification of identifiers in the Sea-Cloud system

The Sea-Cloud Innovative and Experimental Environment is designed for the Strategic Priority Research Program of the ＂Next Generation of Information Technology for Sensing China＂. It was founded by the Chinese Academy of Sciences. There will be billions of heterogeneous devices in the ＂Sea＂ domain. Without unified identifier standards for these devices, issues such as confusion of identifier standards and duplicate identifiers might arise when using these devices in the Sea-Cloud Environment. This paper proposes a unified identifier scheme for the Sea-Cloud system based on different existing identifier standards for different types of devices in the Sea domain. Furthermore, this paper defines a unique identifier for every person who uses smart devices in the Sea domain. Keywords the Sea-Cloud system, identifier standard, Internet of Things