In participatory sensing framework, privacy protection of Internet of Things (IoT) is very important. In this paper, cryptography-based methods are utilized to protect participants’ privacy information in unsecured network channels for dynamic and real-time sensing tasks. The edge computing paradigm is introduced in traditional participatory sensing framework to reduce the network latency. Then, the RC4 stream cipher and logistic mapping are combined to deal with the problems of participants’ limited resources and untruthful third-party platforms. Finally, the product algebra and logistic mapping are combined to deal with the problems of large numbers of participants’ access and poor randomness of keystream. Through extensive performance evaluation and comparison experiments on real-world data, the effectiveness and adaptation of the proposed privacy protection based on stream cipher are verified. It could effectively solve the problem of poor network latency and improve the privacy protection level of IoT.