Nowadays, RFID technology is increasingly become popular and begin to enter many spheres of everyday life. In this paper, we present LocSafe, a "missed-connections" service with privacy grantees based on RFID technology, in order to prove an encounter sharing among users in the past. LocSafe is comprised of three parts: RFID Tags, LE Collectors, and Social Service Provider. We use RFID technology to detect encounters , and use attribute-based encryption and broadcast encryption to establish trust and protect users' privacy. We evaluate LocSafe by an study of "missed-connections" problems and analysis of system implementation.