A hardware-assisted protection and restoration scheme of lost smart phones

Since smart phones are expensive and carrying sensitive personal information including e-mail messages, memos, photos and so on, mobile phone manufacturers are providing services that can protect personal information and help restoration of lost or stolen smart phones. Currently, most of the protection and restoration schemes, which are being used in the commodity smart phones, are software-based. However, such software-based schemes are not effective as they can be easily incapacitated through device initialization, network disconnection, system software modification and so on. This paper categorizes the incapacitation threat methods of the protection and restoration schemes into four, and analyzes how the current software-based schemes cannot function correctly in each threat model. In order to counter these four exploitation models, this paper also proposes a hardware-assisted solution. The proposed scheme is built upon on an additional internal SIM (Subscriber Identifier Module) card and small capacity sub-battery. Finally, this paper assesses the effectiveness of the proposed scheme against the four cases.