Progress in Privacy Protection: A Review of Privacy Preserving Techniques in Recommender Systems, Edge Computing, and Cloud Computing

The digital age is marked by an extraordinary growth in connected devices, leading to a massive influx of data through the Internet [12]. This data is primarily managed by cloud infrastructures. The proliferation of smart devices such as smartphones, tablets, smartwatches, and fitness trackers has transformed them into essential aspects of daily life [8]. These devices accumulate extensive contextual information about users, encompassing their location, activities, and environmental conditions [5]. This information is crucial for applications in predicting user behavior and providing personalized experiences. Mobile crowdsourcing has emerged as a significant phenomenon, where individuals collectively contribute data through various digital channels [32]. Applications in this domain, like traffic monitoring systems, utilize crowd-sourced data to offer real-time insights. However, the process often raises concerns about the privacy of individual contributors. The transparency in data usage and the potential risk of sensitive information being accessed by unauthorized entities are issues that need addressing [11, 26].