The high speed uplink packet access (HSUPA) wireless standard requires extremely high-performance signal processing in the baseband receiver, the most challenging being the chip rate rake receiver. In this paper we describe the architectural enhancements on the IBM's PowerEN processor, to enable it to support the computational requirements of the rake receiver in a fully programmable and scalable fashion. A key feature of these enhancements is a bank-based very-large register file, with embedded single instruction multiple data (SIMD) support. This processor-in-regfile (PIR) strategy is implemented as local computation elements (LCEs) attached to each bank. This overcomes the limitation on the number of register file ports and at the same time enables high degree of parallelism. We show that these enhancements enable the integration of multi-sector HSUPA G-RAKE receivers on a single processor.

With computing increasingly becoming more dispersed, relying on mobile devices, distributed computing, cloud computing, etc. there is an increasing threat from adversaries obtaining physical access to some of the computer systems through theft or security breaches. With such an untrusted computing node, a key challenge is how to provide secure computing environment where we provide privacy and integrity for data and code of the application. We propose SecureME, a hardware-software mechanism that provides such a secure computing environment. SecureME protects an application from hardware attacks by using a secure processor substrate, and also from the Operating System (OS) through memory cloaking, permission paging, and system call protection. Memory cloaking hides data from the OS but allows the OS to perform regular virtual memory management functions, such as page initialization, copying, and swapping. Permission paging extends the OS paging mechanism to provide a secure way for two applications to establish shared pages for inter-process communication. Finally, system call protection applies spatio-temporal protection for arguments that are passed between the application and the OS. Based on our performance evaluation using microbenchmarks, single-program workloads, and multiprogrammed workloads, we found that SecureME only adds a small execution time overhead compared to a fully unprotected system. Roughly half of the overheads are contributed by the secure processor substrate. SecureME also incurs a negligible additional storage overhead over the secure processor substrate.

In the study of social networks, the interplay between network games and network formation is significant yet not well understood. Research in network games seeks to explain strategic interactions between neighbors, whereas research in network formation explores the evolution of link patterns. Our work combines these approaches. We show how cooperative behavior in prisoners' dilemma (PD) interactions can be sustained via the endogenous structure of the social network, demonstrating that the co-evolution of network games and network formation results in new phenomena.

Many systems may have security requirements such as protecting the privacy of data and code stored in the system, ensuring integrity of computations, or preventing the execution of unauthorized code. It is becoming increasingly difficult to ensure such protections as hardware-based attacks, in addition to software attacks, become more widespread and feasible. Many of these attacks target a system during booting before any employed security measures can take effect. In this paper, we propose SHIELDSTRAP, a security architecture capable of booting a system securely in the face of hardware and software attacks targeting the boot phase. SHIELDSTRAP bridges the gap between the vulnerable initialization of the system and the secure steady state execution environment provided by the secure processor. We present an analysis of the security of SHIELDSTRAP against several common boot time attacks. We also show that SHIELDSTRAP requires an on-chip area overhead of only 0.012% and incurs negligible boot time overhead of 0.37 seconds.

As transistor density continues to grow at an exponential rate in accordance to Moore's law, the goal for many Chip Multi-Processor (CMP) systems is to scale the number of on-chip cores proportionally. Unfortunately, off-chip memory bandwidth capacity is projected to grow slowly compared to the desired growth in the number of cores. This creates a situation in which each core will have a decreasing amount of off-chip bandwidth that it can use to load its data from off-chip memory. The situation in which off-chip bandwidth is becoming a performance and throughput bottleneck is referred to as the bandwidth wall problem.

In today's digital world, computer security issues have become increasingly important. In particular, researchers have proposed designs for secure processors that utilize hardware-based memory encryption and integrity verification to protect the privacy and integrity of computation even from sophisticated physical attacks. However, currently proposed schemes remain hampered by problems that make them impractical for use in today's computer systems: lack of virtual memory and Inter-Process Communication support as well as excessive storage and performance overheads. In this article, we propose (1) address independent seed encryption (AISE), a counter-mode-based memory encryption scheme using a novel seed composition, and (2) bonsai Merkle trees (BMT), a novel Merkle tree-based memory integrity verification technique, to eliminate these system and performance issues associated with prior counter-mode memory encryption and Merkle tree integrity verification schemes. We present both a qualitative discussion and a quantitative analysis to illustrate the advantages of our techniques over previously proposed approaches in terms of complexity, feasibility, performance, and storage. Our results show that AISE+BMT reduces the overhead of prior memory encryption and integrity verification schemes from 12% to 2% on average for single-threaded benchmarks on uniprocessor systems, and from 15% to 4% for coscheduled benchmarks on multicore systems while eliminating critical system-level problems.

Multiprocessor computer systems are currently widely used in commercial settings to run critical applications. These applications often operate on sensitive data such as customer records, credit card numbers, and financial data. As a result, these systems are the frequent targets of attacks because of the potentially significant gain an attacker could obtain from stealing or tampering with such data. This provides strong motivation to protect the confidentiality and integrity of data in commercial multiprocessor systems through architectural support. Architectural support is able to protect against software-based attacks, and is necessary to protect against hardware-based attacks. In this work, we propose architectural mechanisms to ensure data confidentiality and integrity in Distributed Shared Memory multiprocessors which utilize a point-to-point based interconnection network. Our approach improves upon previous work in this area, mainly in the fact that our approach reduces performance overheads by significantly reducing the amount of cryptographic operations required. Evaluation results show that our approach can protect data confidentiality and integrity in a 16-processor DSM system with an average overhead of 1.6% and a maximum of only 7% across all SPLASH-2 applications.

In today's digital world, computer security issues have become increasingly important. In particular, researchers have proposed designs for secure processors which utilize hardware-based memory encryption and integrity verification to protect the privacy and integrity of computation even from sophisticated physical attacks. However, currently proposed schemes remain hampered by problems that make them impractical for use in today's computer systems: lack of virtual memory and inter-process communication support as well as excessive storage and performance overheads. In this paper, we propose 1) address independent seed encryption (AISE), a counter-mode based memory encryption scheme using a novel seed composition, and 2) Bonsai Merkle trees (BMT), a novel Merkle tree-based memory integrity verification technique, to eliminate these system and performance issues associated with prior counter-mode memory encryption and Merkle tree integrity verification schemes. We present both a qualitative discussion and a quantitative analysis to illustrate the advantages of our techniques over previously proposed approaches in terms of complexity, feasibility, performance, and storage. Our results show that AISE+BMT reduces the overhead of prior memory encryption and integrity verification schemes from 12% to 2% on average, while eliminating critical system-level problems.

Data security in computer systems has recently become an increasing concern, and hardware-based attacks have emerged. As a result, researchers have investigated hardware encryption and authentication mechanisms as a means of addressing this security concern. Unfortunately, no such techniques have been investigated for Distributed Shared Memory (DSM) multiprocessors, and previously proposed techniques for uni-processor and Symmetric Multiprocessor (SMP) systems cannot be directly used for DSMs. This work is the first to examine the issues involved in protecting secrecy and integrity of data in DSM systems. We first derive security requirements for processor-processor communication in DSMs, and find that different types of coherence messages need different protection. Then we propose and evaluate techniques to provide efficient encryption and authentication of the data in DSM systems. Our simulation results using SPLASH-2 benchmarks show that the execution time overhead for our three proposed approaches is small and ranges from 6% to 8% on a 16-processor DSM system, relative to a similar DSM without support for data secrecy and integrity.

Protection from hardware attacks such as snoopers and mod chips has been receiving increasing attention in computer architecture. This paper presents a new combined memory encryption/authentication scheme. Our new split counters for counter-mode encryption simultaneously eliminate counter overflow problems and reduce per-block counter size, and we also dramatically improve authentication performance and security by using the Galois/counter mode of operation (GCM), which leverages counter-mode encryption to reduce authentication latency and overlap it with memory accesses. Our results indicate that the split-counter scheme has a negligible overhead even with a small (32KB) counter cache and using only eight counter bits per data block. The combined encryption/authentication scheme has an IPC overhead of 5% on average across SPEC CPU 2000 benchmarks, which is a significant improvement over the 20% overhead of existing encryption/authentication schemes