Jiayi Chen 0001 Urs Hengartner Hassan Khan 0002 Mohammad Mannan Chaperone: Real-time Locking and Loss Prevention for Smartphones. 325-342 2020 USENIX Security Symposium https://www.usenix.org/conference/usenixsecurity20/presentation/chen-jiayi conf/uss/2020 db/conf/uss/uss2020.html#ChenHKM20