Biblio

To prevent unauthorized parties from accessing data stored on their smartphones, users have the option of enabling a "lock screen" that requires a secret code (e.g., PIN, drawing a pattern, or biometric) to gain access to their devices. We present a detailed analysis of the smartphone locking mechanisms currently available to billions of smartphone users worldwide. Through a month-long field study, we logged events from a panel of users with instrumented smartphones (N=134). We are able to show how existing lock screen mechanisms provide users with distinct tradeoffs between usability (unlocking speed vs. unlocking frequency) and security. We find that PIN users take longer to enter their codes, but commit fewer errors than pattern users, who unlock more frequently and are very prone to errors. Overall, PIN and pattern users spent the same amount of time unlocking their devices on average. Additionally, unlock performance seemed unaffected for users enabling the stealth mode for patterns. Based on our results, we identify areas where device locking mechanisms can be improved to result in fewer human errors – increasing usability – while also maintaining security.

To resolve the more and more serious problems of sensitive data leakage from Android systems, a kind of method of data protection on encryption storage and encryption transmission is presented in this paper by adopting secure computation environment of SDKEY device. Firstly, a dual-authentication scheme for login using SDKEY and PIN is designed. It is used for login on system boot and lock screen. Secondly, an approach on SDKEY-based transparent encryption storage for different kinds of data files is presented, and a more fine-grained encryption scheme for different file types is proposed. Finally, a method of encryption transmission between Android phones is presented, and two kinds of key exchange mechanisms are designed for next encryption and decryption operation in the following. One is a zero-key exchange and another is a public key exchange. In this paper, a prototype system based on the above solution has been developed, and its security and performance are both analyzed and verified from several aspects.