Title
Group Sparsity Tensor Factorization for Re-Identification of Open Mobility Traces.
Abstract
Re-identification attacks based on a Markov chain model have been widely studied to understand how anonymized traces are linked to users. This approach is known to enable users to be re-identified with high accuracy when an adversary trains a personalized transition matrix for each target user using a large amount of training data, and when all of the anonymized traces are from the target users. In reality, however, the amount of training data for each target user can be very small, since many users disclose only a small amount of their location information to the public. In addition, many of the anonymized traces are from “non-target” users, whose personalized transition matrices cannot be trained in advance. This paper aims to quantify the risk of re-identification in the realistic situation explained earlier. We first utilize the fact that spatial data can form a group structure, and propose group sparsity tensor factorization to effectively train the personalized transition matrices from a small number of training traces. We second formulate a re-identification attack in an “open” scenario, where many of the anonymized traces are from non-target users. Specifically, we regard this type of attack as a biometric verification (or identification) task, and propose a framework and an algorithm for performing this task using a population transition matrix, which is computed from personalized transition matrices. Our experimental results using three real data sets show that a training method using tensor factorization significantly outperforms the maximum likelihood estimation method, and is further improved by incorporating group sparsity regularization.
Year
DOI
Venue
2017
10.1109/TIFS.2016.2631952
IEEE Trans. Information Forensics and Security
Keywords
Field
DocType
Tensile stress,Training,Maximum likelihood estimation,Training data,Markov processes,Spatial databases
Spatial analysis,Population,Data mining,Data set,Markov process,Stochastic matrix,Computer science,Matrix (mathematics),Markov chain,Theoretical computer science,Biometrics
Journal
Volume
Issue
ISSN
12
3
1556-6013
Citations 
PageRank 
References 
2
0.36
29
Authors
3
Name
Order
Citations
PageRank
Takao Murakami15515.02
Atsunori Kanemura2171.89
Hideitsu Hino39925.73