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The recent surge in popularity of smart handheld devices, including smart-phones and tablets, has given rise to new challenges in protection of Personal Identifiable Information (PII). Indeed, modern mobile devices store PII for applications that span from email to SMS and from social media to location-based services increasing the concerns of the end user's privacy. Therefore, there is a clear need and expectation for PII data to be protected in the case of loss, theft, or capture of the portable device. In this paper, we present a novel FUSE (File system in User space) encryption file system to protect the removable and persistent storage on heterogeneous smart gadget devices running the Android platform. The proposed file system leverages NIST certified cryptographic algorithms to encrypt the data-at-rest. We present an analysis of the security and performance trade-offs in a wide-range of usage and load scenarios. Using existing known micro benchmarks in devices using encryption without any optimization, we show that encrypted operations can incur negligible overhead for read operations and up to twenty (20) times overhead for write operations for I/O-intensive programs. In addition, we quantified the database transaction performance and we observed a 50\% operation time slowdown on average when using encryption. We further explore generic and device specific optimizations and gain 10\% to 60\% performance for different operations reducing the initial cost of encryption. Finally, we show that our approach is easy to install and configure across all Android platforms including mobile phones, tablets, and small notebooks without any user perceivable delay for most of the regular Android applications. [ABSTRACT FROM PUBLISHER]

Solid state disk, compared with hard drive disk, has low delay, low energy consumption, high throughput, high bandwidth, and many other advantages. But it is important that, we will meet challenges when using the solid state disk in virtualized environment, because of its own structure and characteristics. But the trim instruction, that plays an important role in space management of SSD, cannot be passed through in a virtualized environment to the underlying solid state disk. So, how to make the trim instruction be handled in virtualized environment will be an urgent problem. An optimized system used in virtualized environment, named Vtrim, is proposed to solve the problem. In the paper, Vtrim monitors the deletion operation in virtual machine and sends the deletion semantic to the Domain 0 immediately. Then the deletion semantic from virtual machine will be translated into the deletion operation in Domain 0. This deletion operation can punch hole on virtual machine disk image, then trigger the trim instruction. In this way, the performance of the SSD in virtualized environment will be improved greatly. Experiments prove that the random write performance will be improved more than 100% at most in the para-virtualization virtual machine with the Vtrim. The average response time will also be reduced to about 40% of the original one in the best case. [ABSTRACT FROM PUBLISHER]