应用预测链接的分布式社会网络隐私保护方法

针对单机工作站环境下处理大规模动态社会网络图时执行效率低,以及动态社会网络发布中数据可用性较差的问题,提出基于预测链接的分布式动态社会网络隐私保护方法D-DSNBLP。该方法通过Pregel-like消息迭代更新模型,实现匿名大规模图数据的并行处理。首先通过快速迭代完成结点分组;其次根据各个组内的结点属性值并行构建候选结点集合;最后通过构建互斥边集合添加边,实现结点的隐私保护。实验表明,D-DSNBLP方法提高了大规模动态社会网络发布的效率,保证了匿名图的数据可用性。     

一种基于K-匿名聚类的可穿戴设备数据重发布方法

近年来,可穿戴设备被广泛地被应用于日常生活。用户量增加造成的可穿戴设备数据重发布是导致隐私泄漏的一个重要原因。为此,数据匿名化重发布方法受到了广泛关注。然而,现有的数据匿名化重发布方法存在两个方面的不足:一方面,现有的数据匿名化重发布算法可能会造成严重的信息损失或用户隐私数据的泄漏;另一方面,现有的数据匿名化重发布算法在兼顾保护用户隐私和减少信息损失的情况下会造成较高的发布成本。为了兼顾隐私安全和数据可用性,并且提高数据重发布算法的效率,结合可穿戴设备自身的特点,提出基于聚类的数据匿名化重发布算法,该算法直接对增量数据进行基于聚类匿名化操作,使数据匿名化重发布更为高效。此外,在数据量较大的应用场景中,基于聚类的数据匿名化重发布算法可以有效减少信息损失。实验结果表明,基于聚类的数据匿名化重发布算法能够在保证用户隐私安全的前提下减少信息的损失并且提高执行效率。     

D-VSSP:分布式社会网络隐私保护算法

针对传统社会网络隐私保护技术对大规模社会网络数据处理效率较低的问题,提出一种分布式结点分裂匿名社会网络隐私保护算法(Distributed-Vertex Splitting Social Network Privacy Preserving,D-VSSP)。D-VSSP算法利用MapReduce和Pregel-like分布式计算模型处理社会网络图数据。首先基于MapReduce分布式计算模型对大图中的结点的标签信息进行标签平凡化、标签平凡化分组和精确分组处理;然后基于Pregel-like的消息传递机制,选举结点分裂,进行分布式结点分裂匿名。实验结果表明,在 对大规模社会网络数据的处理效率上, D-VSSP算法优于传统算法。     

社交网络高效高精度去匿名化算法

自从社交网络成为重要的研究课题,社交网络隐私保护也成为了重要的研究内容,尤其是关于公开发布以供研究的大规模社交网络图数据的隐私保护。为了评估用户的隐私风险,研究者们设计了不同的方法来对图进行去匿名化,在不同的图网络中识别个体的身份。然而,当前的去匿名化算法或者需要高质量的种子匹配,或者在精确度和效率上颇有不足。本文提出了一种高效高精度的无种子去匿名化算法"RoleMatch",基于社交网络的拓扑结构识别个体身份。该算法包括（1）一种新型的可以快速计算的两图结点间相似度度量方法"RoleSim++",和（2）一种有效的结点匹配算法,此法同时考虑了结点间的相似度和中间匹配结果的反馈。在实验部分,利用LiveJournal的数据,拿RoleMatch对比了多种流行的匿名化算法,并根据实际应用情景,在传统实验的基础上增加了局部去匿名化的实验,实验结果验证了本文提出的去匿名化算法的优秀性能。     

保护社区结构的社会网络匿名技术

针对当前社会网络隐私保护方法存在社区结构破坏严重、单工作站处理数据能力低等不足,提出一种保护社区结构的社会网络度匿名SNDA-PCS(socialnetworkdegreeanonymityforprotectingcommunitystructure)方法。社会网络社区发现使用分裂聚集算法,由聚合向量构造的压缩二叉树分组匿名度序列,添加虚拟顶点构造匿名图,根据顶点所属社区设计虚拟顶点删除-添加算法以提高发布图数据可用性。SNDA-PCS算法基于大规模并行图处理系统Graph X实现,实验结果表明,SNDA-PCS算法在满足匿名要求的同时保证了社区结构的可用性。     

面向查询服务的数据隐私保护算法

个性化信息服务提高了Web查询精度,但同时也带来数据隐私保护的问题.尤其在面向服务的架构(SOA)中,部署个性化应用时,如何解决隐私保护,这对于个性化服务是一个挑战.随着隐私安全成为微数据发布过程中越来越重要的问题,好的匿名化算法就显得尤为重要.论文总结了前人研究中考虑到准标识符对敏感属性影响的k-匿名算法,提出了直接通过匿名化数据计算准标识符对敏感属性效用的方法以及改进的效用矩阵,同时为了更好地衡量匿名化数据的信息损失,论文中提出了改进的归一确定性惩罚的评价指标,从匿名化数据隐私安全的角度进行分析,实现了改进L-diversity算法,即基于信息损失惩罚的满足L-diversity的算法.它是准标识符对不同敏感属性效用的、并具有较好隐私安全的改进算法.     

基于抽样路径的K-匿名隐私保护算法

K-匿名是信息隐私保护的一种常用技术,而使用K-匿名技术不可避免会造成发布数据的信息损失,因此,如何提高K-匿名化后数据集的可用性一直以来都是K-匿名隐私保护的研究重点。对此提出了一种基于抽样路径的局域泛化算法——SPOLG算法。该算法基于泛化格寻找信息损失较小的泛化路径,为减少寻径时间,引入等概率抽样的思想,选用等概率抽样中的系统抽样方法进行取样,利用样本代替数据集在泛化格上寻找目标泛化路径,最后在该路径上对数据集进行泛化。同时,本算法使用局域泛化技术,能够降低信息损失量,提高发布数据集的可用性。实验结果证明,本算法匿名化的数据集信息损失度低,数据可用性高。     

防止路径攻击的加权社会网络匿名化技术

随着社会网络的普及,社会网络数据的隐私保护问题,已经成为数据隐私研究领域学者普遍关注的热点问题。由于隐私信息异常广泛,攻击者可以利用多种背景知识进行隐私攻击。现有的隐私保护技术,大多针对简单社会网络,并不适用于加权社会网络。对加权社会网络中的路径隐私泄露问题进行了研究,针对最短路径识别提出了加权图k-可能路径匿名（k-possible path anonymity,KPPA）隐私保护模型,来防止基于加权社会网络的最短路径隐私攻击,设计了一种基于权重泛化的匿名方法来实现KPPA算法。通过在真实数据集上的大量测试研究,证明了KPPA算法对于加权图路径隐私保护的有效性,同时基于KPPA算法可以保留原图结构性质,提高权重信息的可用性。     

社会网络中基于节点平均度的k-度匿名隐私保护方案

社会网络数据的发布可能导致用户隐私被泄露,例如用户的身份信息可能被恶意攻击者通过分析网络中节点的度数识别出来,针对这个问题提出一种基于节点平均度的k-度匿名隐私保护方案.方案首先利用基于平均度的贪心算法对社会网络节点进行划分,使得同一分组中节点的度都修改成平均度,从而生成k-度匿名序列;然后利用优先保留重要边的图结构修改方法对图进行修改,从而实现图的k-度匿名化.本方案在生成k-度匿名序列时引入平均度,提高了聚类的精度,降低了图结构修改的代价.同时,由于在图结构修改时考虑了衡量边重要性的指标—邻域中心性,重要的边被优先保留,保持了稳定的网络结构.实验结果表明,本方案不仅能有效地提高网络抵抗度攻击的能力,还能极大降低信息损失量,在保护用户隐私的同时提高了发布数据的可用性.     

图数据发布隐私保护的聚类匿名方法

社交网络中积累的海量信息构成一类图大数据,为防范隐私泄露,一般在发布此类数据时需要做匿名化处理.针对现有匿名方案难以防范同时以结构和属性信息为背景知识的攻击的不足,研究一种基于节点连接结构和属性值的属性图聚类匿名化方法,利用属性图表示社交网络数据,综合根据节点间的结构和属性相似度,将图中所有节点聚类成一些包含节点个数不小于k的超点,特别针对各超点进行匿名化处理.该方法中,超点的子图隐匿和属性概化可以分别防范一切基于结构和属性背景知识的识别攻击.另外,聚类过程平衡了节点间的连接紧密性和属性值相近性,有利于减小结构和属性的总体信息损失值,较好地维持数据的可用性.实验结果表明了该方法在实现算法功能和减少信息损失方面的有效性.     

High utility K-anonymization for social network publishing

Privacy and utility are two main desiderata of good sensitive information publishing schemes. For publishing social networks, many existing algorithms rely on \(k\) -anonymity as a criterion to guarantee privacy protection. They reduce the utility loss by first using the degree sequence to model the structural properties of the original social network and then minimizing the changes on the degree sequence caused by the anonymization process. However, the degree sequence-based graph model is simple, and it fails to capture many important graph topological properties. Consequently, the existing anonymization algorithms that rely on this simple graph model to measure utility cannot guarantee generating anonymized social networks of high utility. In this paper, we propose novel utility measurements that are based on more complex community-based graph models. We also design a general \(k\) -anonymization framework, which can be used with various utility measurements to achieve \(k\) -anonymity with small utility loss on given social networks. Finally, we conduct extensive experimental evaluation on real datasets to evaluate the effectiveness of the new utility measurements proposed. The results demonstrate that our scheme achieves significant improvement on the utility of the anonymized social networks compared with the existing anonymization algorithms. The utility losses of many social network statistics of the anonymized social networks generated by our scheme are under 1 % in most cases.     

社交网络下的不确定图隐私保护算法

社交网络平台的快速普及使得社交网络中的个人隐私泄露问题愈发受到用户的关心,传统的数据隐私保护方法无法满足用户数量巨大、关系复杂的社交网络隐私保护需求.图修改技术是针对社交网络数据的隐私保护所提出的一系列隐私保护措施,其中不确定图是将确定图转化为概率图的一种隐私保护方法.主要研究了不确定图中边概率赋值算法,提出了基于差分隐私的不确定图边概率赋值算法,该算法具有双重隐私保障,适合社交网络隐私保护要求高的场景.同时提出了基于三元闭包的不确定图边概率分配算法,该算法在实现隐私保护的同时保持了较高的数据效用,适合简单的社交网络隐私保护场景.分析与比较表明：与（k,ε）-混淆算法相比,基于差分隐私的不确定图边概率赋值算法可以实现较高的隐私保护效果,基于三元闭包的不确定图边概率分配算法具有较高的数据效用性.最后,为了衡量网络结构的失真程度,提出了基于网络结构熵的数据效用性度量算法,该算法能够度量不确定图与原始图结构的相似程度.     

Anonymizing popularity in online social networks with full utility

With the rapid growth of social network applications, more and more people are participating in social networks. Privacy protection in online social networks becomes an important issue. The illegal disclosure or improper use of users’ private information will lead to unaccepted or unexpected consequences in people’s lives. In this paper, we concern on authentic popularity disclosure in online social networks. To protect users’ privacy, the social networks need to be anonymized. However, existing anonymization algorithms on social networks may lead to nontrivial utility loss. The reason is that the anonymization process has changed the social network’s structure. The social network’s utility, such as retrieving data files, reading data files, and sharing data files among different users, has decreased. Therefore, it is a challenge to develop an effective anonymization algorithm to protect the privacy of user’s authentic popularity in online social networks without decreasing their utility. In this paper, we first design a hierarchical authorization and capability delegation (HACD) model. Based on this model, we propose a novel utility-based popularity anonymization (UPA) scheme, which integrates proxy re-encryption with keyword search techniques, to tackle this issue. We demonstrate that the proposed scheme can not only protect the users’ authentic popularity privacy, but also keep the full utility of the social network. Extensive experiments on large real-world online social networks confirm the efficacy and efficiency of our scheme.     

Experiments and Analyses of Anonymization Mechanisms for Trajectory Data Publishing

With the advancing of location-detection technologies and the increasing popularity of mobile phones and other location-aware devices, trajectory data is continuously growing. While large-scale trajectories provide opportunities for various applications, the locations in trajectories pose a threat to individual privacy. Recently, there has been an interesting debate on the reidentifiability of individuals in the Science magazine. The main finding of Sánchez et al. is exactly opposite to that of De Montjoye et al., which raises the first question: "what is the true situation of the privacy preservation for trajectories in terms of reidentification?' Furthermore, it is known that anonymization typically causes a decline of data utility, and anonymization mechanisms need to consider the trade-off between privacy and utility. This raises the second question: "what is the true situation of the utility of anonymized trajectories?' To answer these two questions, we conduct a systematic experimental study, using three real-life trajectory datasets, five existing anonymization mechanisms (i.e., identifier anonymization, grid-based anonymization, dummy trajectories, k-anonymity and ε-differential privacy), and two practical applications (i.e., travel time estimation and window range queries). Our findings reveal the true situation of the privacy preservation for trajectories in terms of reidentification and the true situation of the utility of anonymized trajectories, and essentially close the debate between De Montjoye et al. and Sánchez et al.To the best of our knowledge, this study is among the first systematic evaluation and analysis of anonymized trajectories on the individual privacy in terms of unicity and on the utility in terms of practical applications.     

Privacy-preserving graph publishing with disentangled variational information bottleneck

Social networks collect enormous amounts of user personal and behavioral data, which could threaten users' privacy if published or shared directly. Privacy-preserving graph publishing (PPGP) can make user data available while protecting private information. For this purpose, in PPGP, anonymization methods like perturbation and generalization are commonly used. However, traditional anonymization methods are challenging in balancing high-level privacy and utility, ineffective at defending against both various link and hybrid inference attacks, as well as vulnerable to graph neural network (GNN)-based attacks. To solve those problems, we present a novel privacy-disentangled approach that disentangles private and non-private information for a better privacy-utility trade-off. Moreover, we propose a unified graph deep learning framework for PPGP, denoted privacy-disentangled variational information bottleneck (PDVIB). Using low-dimensional perturbations, the model generates an anonymized graph to defend against various inference attacks, including GNN-based attacks. Particularly, the model fits various privacy settings by employing adjustable perturbations at the node level. With three real-world datasets, PDVIB is demonstrated to generate robust anonymous graphs that defend against various privacy inference attacks while maintaining the utility of non-private information.     

An Iteration-Based Differentially Private Social Network Data Release

Online social networks provide an unprecedented opportunity for researchers to analysis various social phenomena. These network data is normally represented as graphs, which contain many sensitive individual information. Publish these graph data will violate users’ privacy. Differential privacy is one of the most influential privacy models that provides a rigorous privacy guarantee for data release. However, existing works on graph data publishing cannot provide accurate results when releasing a large number of queries. In this paper, we propose a graph update method transferring the query release problem to an iteration process, in which a large set of queries are used as update criteria. Compared with existing works, the proposed method enhances the accuracy of query results. The extensive experiment proves that the proposed solution outperforms two state-of-the-art methods, the Laplace method and the correlated method, in terms of Mean Absolute Value. It means our methods can retain more utility of the queries while preserving the privacy.     

<Emphasis Type="Italic">k</Emphasis>-Degree anonymity and edge selection: improving data utility in large networks

The problem of anonymization in large networks and the utility of released data are considered in this paper. Although there are some anonymization methods for networks, most of them cannot be applied in large networks because of their complexity. In this paper, we devise a simple and efficient algorithm for k-degree anonymity in large networks. Our algorithm constructs a k-degree anonymous network by the minimum number of edge modifications. We compare our algorithm with other well-known k-degree anonymous algorithms and demonstrate that information loss in real networks is lowered. Moreover, we consider the edge relevance in order to improve the data utility on anonymized networks. By considering the neighbourhood centrality score of each edge, we preserve the most important edges of the network, reducing the information loss and increasing the data utility. An evaluation of clustering processes is performed on our algorithm, proving that edge neighbourhood centrality increases data utility. Lastly, we apply our algorithm to different large real datasets and demonstrate their efficiency and practical utility.     

The <Emphasis Type="Italic">k</Emphasis>-anonymity and <Emphasis Type="Italic">l</Emphasis>-diversity approaches for privacy preservation in social networks against neighborhood attacks

Recently, more and more social network data have been published in one way or another. Preserving privacy in publishing social network data becomes an important concern. With some local knowledge about individuals in a social network, an adversary may attack the privacy of some victims easily. Unfortunately, most of the previous studies on privacy preservation data publishing can deal with relational data only, and cannot be applied to social network data. In this paper, we take an initiative toward preserving privacy in social network data. Specifically, we identify an essential type of privacy attacks: neighborhood attacks. If an adversary has some knowledge about the neighbors of a target victim and the relationship among the neighbors, the victim may be re-identified from a social network even if the victim’s identity is preserved using the conventional anonymization techniques. To protect privacy against neighborhood attacks, we extend the conventional k-anonymity and l-diversity models from relational data to social network data. We show that the problems of computing optimal k-anonymous and l-diverse social networks are NP-hard. We develop practical solutions to the problems. The empirical study indicates that the anonymized social network data by our methods can still be used to answer aggregate network queries with high accuracy.     

A data driven anonymization system for information rich online social network graphs

In recent years, online social networks have become a part of everyday life for millions of individuals. Also, data analysts have found a fertile field for analyzing user behavior at individual and collective levels, for academic and commercial reasons. On the other hand, there are many risks for user privacy, as information a user may wish to remain private becomes evident upon analysis. However, when data is anonymized to make it safe for publication in the public domain, information is inevitably lost with respect to the original version, a significant aspect of social networks being the local neighborhood of a user and its associated data. Current anonymization techniques are good at identifying risks and minimizing them, but not so good at maintaining local contextual data which relate users in a social network. Thus, improving this aspect will have a high impact on the data utility of anonymized social networks. Also, there is a lack of systems which facilitate the work of a data analyst in anonymizing this type of data structures and performing empirical experiments in a controlled manner on different datasets. Hence, in the present work we address these issues by designing and implementing a sophisticated synthetic data generator together with an anonymization processor with strict privacy guarantees and which takes into account the local neighborhood when anonymizing. All this is done for a complex dataset which can be fitted to a real dataset in terms of data profiles and distributions. In the empirical section we perform experiments to demonstrate the scalability of the method and the improvement in terms of reduction of information loss with respect to approaches which do not consider the local neighborhood context when anonymizing.     

改进的k度匿名图构造算法

在社交网络中, 为防范用户隐私泄漏, 在用户数据发布前需要做匿名化处理. 针对以节点度数为背景知识的隐私攻击, 将社交网络匿名化问题建模为图的k度匿名化问题; 其主要方法是对图添加尽可能少的边或点来满足度匿名化要求, 其中要求添加边或点较少是期望尽可能保持原图结构特性. 目前, 加边类算法并不能很好地保留平均路径长度等结构特性; 加边且可加点类算法尽管能更好地保留原图结构特性, 但添加的边或点较多. 本文融合两类算法的策略提出改进算法. 新算法利用贪心法生成匿名度序列, 然后基于社区结构加边, 并且优先满足其匿名代价高于平均匿名代价的节点的匿名化要求; 若加边不能完成匿名化, 则通过加点实现图匿名化. 真实数据集上的实验结果表明新算法能更好地保留图的几种典型的结构特性, 并且添加的边或点更少.