共查询到17条相似文献,搜索用时 140 毫秒
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为了准确检测协同过滤推荐系统中的用户概貌注入攻击,从攻击的目的性考虑,通过对攻击概貌中目标项目与填充项目之间的特征差异进行分析,提出一种项目评分背离度的计算方法;利用项目评分背离度来确定受攻击的目标项目,并在此基础上提出一种基于目标项目识别的用户概貌注入攻击检测算法.实验结果表明,该算法进一步提高了攻击检测的精度,确保了系统推荐的质量. 相似文献
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用户多兴趣下基于信任的协同过滤算法研究 总被引:3,自引:0,他引:3
张富国 《小型微型计算机系统》2008,29(8)
协同过滤技术是目前电子商务推荐系统最为有效的信息过滤技术之一.最近的研究尝试在推荐过程中引入信任模型来提高推荐的准确性和抵御"托"攻击.但在用户多兴趣的情况下,属于不同主题的项目需要不同的可信赖人员来推荐,传统的概貌级信任模型已不再适用.本文提出主题级信任计算模型以及基于主题级信任的协同过滤算法.一系列的实验结果表明,该算法在不牺牲鲁棒性的同时,有效地提高了推荐的准确性. 相似文献
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协同过滤推荐系统面临着托攻击的安全威胁。研究抵御托攻击的鲁棒性推荐算法已成为一个迫切的课题。传统的鲁棒性推荐算法在算法稳定性与推荐准确度之间难以权衡。针对该问题,首先定义一种用户可信度指标,其次改进传统的相似度计算方法,通过结合用户可信度与改进的相似度,滤除攻击概貌,为目标用户作出推荐。实验表明,与传统算法相比,本文算法具备更强的稳定性,同时保持了良好的推荐准确度。 相似文献
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基于用户声誉的鲁棒协同推荐算法 总被引:2,自引:0,他引:2
随着推荐系统在电子商务界的快速发展以及取得的巨大经济收益, 有目的性的托攻击是目前协同过滤系统面临的重大安全威胁, 研究一种可抵御攻击的鲁棒推荐技术已成为目前推荐系统领域的重要课题.本文利用历史记录得到用户声誉, 建立声誉推荐系统, 并结合协同过滤推荐领域内的隐语义模型, 提出基于用户声誉的隐语义模型鲁棒协同算法.本文提出的算法从人为攻击和自然噪声两个方面对系统的鲁棒性进行了改善.在真实的数据集 Movielens 1M 上的实验表明, 与现有的鲁棒性推荐算法相比, 这种算法具有形式简单、可解释性强、稳定的特点, 且在精度得到一定提升的情况下大大增强了系统抵御攻击的能力. 相似文献
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基于双重邻居选取策略的协同过滤推荐算法 总被引:1,自引:0,他引:1
协同过滤是电子商务推荐系统中应用最成功的推荐技术之一,但是传统的协同过滤推荐算法存在推荐精度低和抗攻击能力差的缺陷.针对这些问题,提出了一种基于双重邻居选取策略的协同过滤推荐算法.首先基于用户相似度计算的结果,动态选取目标用户的兴趣相似用户集.然后提出了一种用户信任计算模型,根据用户的评分信息,计算得到目标用户对兴趣相似用户的信任度,并以此作为选取可信邻居用户的依据.最后,利用双重邻居选取策略,完成对目标用户的推荐.实验结果表明该算法不仅提高了系统推荐精度,而且具有较强的抗攻击能力. 相似文献
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Min GAO Bin LING Linda YANG Junhao WEN Qingyu XIONG Shun LI 《Frontiers of Computer Science》2019,13(2):231
Collaborative filtering (CF) is a technique commonly used for personalized recommendation and Web service quality-of-service (QoS) prediction. However, CF is vulnerable to shilling attackers who inject fake user profiles into the system. In this paper, we first present the shilling attack problem on CF-based QoS recommender systems for Web services. Then, a robust CF recommendation approach is proposed from a user similarity perspective to enhance the resistance of the recommender systems to the shilling attack. In the approach, the generally used similarity measures are analyzed, and the DegSim (the degree of similarities with top k neighbors) with those measures is selected for grouping and weighting the users. Then, the weights are used to calculate the service similarities/differences and predictions.We analyzed and evaluated our algorithms using WS-DREAM and Movielens datasets. The experimental results demonstrate that shilling attacks influence the prediction of QoS values, and our proposed features and algorithms achieve a higher degree of robustness against shilling attacks than the typical CF algorithms. 相似文献
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在采用协同过滤技术的推荐系统中,恶意用户通过注入大量虚假概貌使系统的推荐结果产生偏离,达到其攻击目的。为了检测托攻击,根据用户的评分值或基于攻击时间的集中性假设,从不同视角提取攻击概貌的特征。但是,这些基于人工特征的检测方法严重依赖于特征工程的质量,而且人工提取的检测特征多限于特定类型的攻击,提取特征也需要较高的知识成本。针对这些问题,从用户评分项目的时间偏好信息入手,提出一种利用深度稀疏自动编码器自动提取检测特征的托攻击集成检测方法。利用小波变换将项目在不同时间间隔内的流行度设定为多个等级,对用户的评分数据预处理得到用户-项目时间流行度等级矩阵。然后,采用深度稀疏自动编码器对用户-项目时间流行度等级矩阵自动进行特征提取,得到用户评分模式的低层特征表达,消除了传统的人工特征工程。以SVM作为基分类器,在深度稀疏自动编码器的每层提取特征并进行攻击检测,生成最终的集成检测结果。在Netflix数据集上的实验表明,提出的检测方法对均值攻击、AoP攻击、偏移攻击、高级项目攻击、高级用户攻击具有较好的检测效果。 相似文献
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Collaborative filtering (CF) technique is capable of generating personalized recommendations. However, the recommender systems utilizing CF as their key algorithms are vulnerable to shilling attacks which insert malicious user profiles into the systems to push or nuke the reputations of targeted items. There are only a small number of labeled users in most of the practical recommender systems, while a large number of users are unlabeled because it is expensive to obtain their identities. In this paper, Semi-SAD, a new semi-supervised learning based shilling attack detection algorithm is proposed to take advantage of both types of data. It first trains a naïve Bayes classifier on a small set of labeled users, and then incorporates unlabeled users with EM-λ to improve the initial naïve Bayes classifier. Experiments on MovieLens datasets are implemented to compare the efficiency of Semi-SAD with supervised learning based detector and unsupervised learning based detector. The results indicate that Semi-SAD can better detect various kinds of shilling attacks than others, especially against obfuscated and hybrid shilling attacks. 相似文献
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基于数据非随机缺失机制的推荐系统托攻击探测 总被引:1,自引:0,他引:1
协同过滤推荐系统极易受到托攻击的侵害. 开发托攻击探测技术已成为保障推荐系统可靠性与鲁棒性的关键. 本文以数据非随机缺失机制为依托,对导致评分缺失的潜在因素进行解析, 并在概率产生模型框架内将这些潜在因素与Dirichlet过程相融合, 提出了用于托攻击探测的缺失评分潜在因素分析(Latent factor analysis for missing ratings, LFAMR)模型. 实验表明,与现有探测技术相比, LFAMR具备更强的普适性和无监督性, 即使缺乏系统相关先验知识,仍可有效探测各种常见托攻击. 相似文献
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Collaborative filtering systems are essentially social systems which base their recommendation on the judgment of a large number of people. However, like other social systems, they are also vulnerable to manipulation by malicious social elements. Lies and Propaganda may be spread by a malicious user who may have an interest in promoting an item, or downplaying the popularity of another one. By doing this systematically, with either multiple identities, or by involving more people, malicious user votes and profiles can be injected into a collaborative recommender system. This can significantly affect the robustness of a system or algorithm, as has been studied in previous work. While current detection algorithms are able to use certain characteristics of shilling profiles to detect them, they suffer from low precision, and require a large amount of training data. In this work, we provide an in-depth analysis of shilling profiles and describe new approaches to detect malicious collaborative filtering profiles. In particular, we exploit the similarity structure in shilling user profiles to separate them from normal user profiles using unsupervised dimensionality reduction. We present two detection algorithms; one based on PCA, while the other uses PLSA. Experimental results show a much improved detection precision over existing methods without the usage of additional training time required for supervised approaches. Finally, we present a novel and highly effective robust collaborative filtering algorithm which uses ideas presented in the detection algorithms using principal component analysis. 相似文献
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推荐系统托攻击检测算法监督学习过度依赖训练集,无监督算法依赖于攻击概貌之间相似性。本文提出一种半监督托攻击检测模型,对标记用户分类计算簇中心,给出中心用户相似度特征属性。对不同攻击选择合适的特征指标,把输入用户划分到不同的簇集中,通过簇集中输入用户全部评分项为最大值的均值与标记用户对该项均值差,确定攻击项。依据特征指标对不同簇集进行两次分类,进而确定攻击对象。实验证明,该检测算法对不同的托攻击有较高的检测准确率。 相似文献