車輛網路中低成本的位置隱私保護之研究

Low-Cost Location Privacy Protection for Vehicular Networks

羅堂德(Tang-Te Lo)

指導教授 ： 逄愛君

國立臺灣大學/電機資訊學院/資訊網路與多媒體研究所/碩士(2013年)

https://doi.org/10.6342/NTU.2013.10087

摘要

位置隱私權是位置服務中已經被廣泛討論的重要的議題，許多保護位置隱私的方法已經被提出。由於更換假名的位置隱私保護方法，不需要額外的第三方伺服器，也不會造成額外的通訊成本，因此已經被廣泛的討論。然而，這些已經存在的位置隱私保護方法，並未考慮更換假名的次數。當更換假名的同時，在位置伺服器上的服務將會中斷且路由必須重新建立，這些現象將導致通訊成本提高。由於此現象的發現，本篇論文提出了一個低成本的位置隱私之保護方法，來達到更好的位置資訊保護，並同時最小化無法服務的的時間。本論文的考量因素包含假名的維持時間，車輛的移動速度以及車輛的行進方向。根據以上考量因素的組合，將包含四個方法AS、AD、SD 和ADS。本論文提出評估指標"分數"來評估更換假名的方法之效率。根據保護率以及更換假名的成本，"分數"被定義為在所有旅行時間中安全且可使用的時間之比例。模擬結果顯示目前已經存在的方法，例如SLOW 和SPOT 雖然可以有比較高的安全性，但這些方法將產生由於更換假名次數過多而造成的成本。模擬結果也顯示，AS、AD 和ADS 在少量更換假名且高安全性的情況下都有不錯的表現，其中ADS 是表現最好的方法。

關鍵字

位置隱私權 ； 位置服務 ； 評估指標 ； 假名 ； 車輛隨意網路

並列摘要

In a Vehicular Ad-hoc Network (VANET) environment, it is known that Location-Based Service (LBS) leads to serious concerns on location privacy. To tackle this issue, different mechanisms of the location privacy in VANET have been proposed in the literature. Among them, pseudonym changing mechanisms do not need a trusted third party location server and have no the drawbacks of extra communication cost, and hence have attracted a wide spread attention. However, most existing location privacy mechanisms based on pseudonym changing do not take the number of pseudonym changes into account. While performing pseudonym changes, the services from the location server will be interrupted and the routing has to be reestablished incurring communication overheads. In light of this observation, this study proposes low cost location privacy mechanisms to achieve better location privacy protection and to minimize the service unavailable time as well. Our intention is to devise criteria for performing pseudonym changes by considering the age of pseudonyms, the speed of the vehicles and the moving direction of vehicles. Four mechanisms AS, AD, SD and ADS are devised by using the combination of these factors. Also, to evaluate the effectiveness of the pseudonym change mechanisms, an evaluation metric Score is proposed. By considering both the protection rate and the overhead of pseudonym changes, Score is formulated to represent the ratio of the safe and available time to the whole travel time. Simulation results show that although some exiting mechanisms, such as SLOW and SPOT, can achieve high security level but they are not really effective due to the overhead incurred from a large number of pseudonym changes. Simulation results also show that the proposed mechanism AS, AD, and ADS have good performance in terms of high protection rate with less number of pseudonym changes, and, in particular, ADS always has the best performance.

並列關鍵字

Location Privacy ； Location-based Service ； Evaluation Metric ； Pseudonym ； VANETs

參考文獻

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