关键词: 基于位置的服务（LBS）, k-匿名, 数字签名, 用户协作, 隐私保护

Abstract: As a new service model, location-based service brings people great convenience. But, users’ location privacy is facing a lot of threat. According to the actual application on location privacy protection in LBS and the existing privacy protection model, the paper analyzes the threat when using the method based on users’ cooperation to protect location privacy and the users are not fully confidential, and proposes an algorithm called User-Cooperation Security（UCA） spatial algorithm. The algorithm introduces digital signature into the peer-to-peer spatial cloaking algorithm, so that users can realize the identity authentication with others and encrypt the sensitive messages with the private key of receiving party before they send them, avoiding the attackers stealing their position. Besides, the algorithm can discover more nodes when the users broadcast discovering messages again after a little time. Through the experiment, the algorithm is proved that it can protect users’ location privacy better.

Key words: Location Based Services（LBS）, k-anonymity, digital signature, users&rsquo, cooperation, privacy protection