Recently, return-oriented programming (ROP) attacks have been rapidly increasing. In this letter, we introduce a fast and space-efficient defense technique, called zero-sum defender, that can respond against general ROP attacks. Our technique generates additional codes, at compile time, just before return instructions to check whether the execution has been abused by ROP attacks. We achieve very low runtime overhead with very small increase in file size. In our experimental results, performance overhead is 1.7%, and file size overhead is 4.5%.

Flash storage suffers from severe performance degradation due to its inherent internal synchronization overhead. Especially, flushing an L2P (logical address to physical address) mapping table significantly contributes to the performance degradation. To relieve the problem, we propose an efficient L2P mapping table management scheme on the flash storage, which works along with a small-sized NVRAM. It flushes L2P mapping table from DRAM to NVRAM or flash memory selectively. In our experiments, the proposed scheme shows up to 9.37× better performance than conventional schemes.

We suggest a new probe message structure and an efficient probe-based deadlock detection and recovery algorithm that can be used in distributed database systems. We determine the characteristics of the probe messages and suggest an algorithm that can reduce the communication cost required for deadlock detection and recovery.

The mobile computing system is a set of functions on a distributed environment organized to support mobile hosts. In this environment, mobile hosts should be able to move without any constraints and should remain connected to the network even while moving. Also, they should be able to get necessary information regardless of their current location and time. Distributed mutual exclusion methods for supporting distributed algorithms have hitherto been designed for networks only with static hosts. However, with the emergence of mobile computing environments, a new distributed mutual exclusion method needs to be developed for integrating mobile hosts with underlying distributed systems. In the sense, many issues that should be considered stem from three essential properties of mobile computing system such as wireless communication, portability, and mobility. Thus far, distributed mutual exclusion methods for mobile computing environments were designed based on a token ring structure, which has the drawback of requiring high costs in order to locate mobile hosts. In this paper, we propose not only a distributed mutual exclusion method that can reduce such costs by structuring the entire system as a tree-based logical structure but also recovery schemes that can be applied when a node failure occurs. Finally, we evaluate the operation costs for the mutual exclusion scheme and the recovery scheme.

In ubiquitous computing environments supporting mobile agents, agent anonymity is a critical issue in protecting the privacy of users. Agent anonymity means that no other entity can identify the identity of the agent performing an action. For agent anonymity, the information, that the user creates or contributes to, and the agent itself should not be revealed, which can be accomplished by hiding the identity of the agent working on behalf of the user. In this paper, an anonymity framework is described for mobile agent systems, providing agent anonymity facilities using agent identity encryption and access control facilities, based on partially blind signature. It is possible to service anonymous mobile agents in ubiquitous computing environments while reducing the abuse resulting from anonymity, by deploying the proposed agent anonymity framework.

Virtualization is no longer an emerging research area since the virtual processor and memory operate as efficiently as the physical ones. However, I/O performance is still restricted by the virtualization overhead caused by the costly and complex I/O virtualization mechanism, in particular by massive exits occurring on the guest-host switch and redundant processing of the I/O stacks at both guest and host. A para-virtual device driver may reduce the number of exits to the hypervisor, whereas the network stacks in the guest OS are still duplicated. Previous work proposed a socket-outsourcing technique that bypasses the redundant guest network stack by delivering the network request directly to the host. However, even by bypassing the redundant network paths in the guest OS, the obtained performance was still below 60% of the native device, since notifications of completion still depended on the hypervisor. In this paper, we propose vCanal, a novel network virtualization framework, to improve the performance of network access in the virtual machine toward that of the native machine. Implementation of vCanal reached 96% of the native TCP throughput, increasing the UDP latency by only 4% compared to the native latency.

NAND flash storage devices, such as eMMCs and microSD cards, are now widely used in mobile devices. In this paper, we propose a novel buffer replacement scheme for mobile NAND flash storages. It efficiently improves write performance by evicting pages flash-friendly and maintains high cache hit ratios by managing pages in order of recency. Our experimental results show that the proposed scheme outperforms the best performing scheme in the recent literature, Sp.Clock, by 48%.

A concurrent FIFO queue is a widely used fundamental data structure for parallelizing software. In this letter, we introduce a novel concurrent FIFO queue algorithm for multicore architecture. We achieve better scalability by reducing contention among concurrent threads, and improve performance by optimizing cache-line usage. Experimental results on a server with eight cores show that our algorithm outperforms state-of-the-art algorithms by a factor of two.