The availability and the accuracy of the data dictate the success of a data mining application. Increasingly, there is a need to resort to on-line data collection to address the problem of data availability. However, participants in online data collection applications are naturally distrustful of the data collector as well as their peer respondents, resulting in inaccurate data collected as the respondents refuse to provide truthful data in fear of collusion attacks. The current anonymity-preserving solutions for on-line data collection are unable to adequately resist such attacks in a scalable fashion. In this paper, we present an efficient anonymous data collection protocol for a malicious environment such as the Internet. The protocol employs cryptographic and random shuffling techniques to preserve participants' anonymity. The proposed method is collusion-resistant and guarantees that an attacker will be unable to breach an honest participant's anonymity unless she contr...