Ruby B. Lee, the Forrest G. Hamrick Professor in Engineering and professor of electrical and computer engineering, will transition to emeritus status after twenty-four years on the Princeton faculty. She is also associated faculty in the Department of Computer Science, the Center for Information Technology Policy, and the Andlinger Center for Energy and the Environment. Ruby came to Princeton in 1998 after an illustrious career in Silicon Valley, where she pioneered computer innovations at Hewlett-Packard Company (HP). 

Ruby grew up in Singapore, the youngest of six children, and went to top schools there. She chose Cornell University for her undergraduate studies, where she majored in computer science and comparative literature and graduated Phi Beta Kapa in 1973. Ruby continued her education at Stanford University, where she received her master of science in computer science and computer engineering in 1975 and her Ph.D. in electrical engineering in 1980. During her Ph.D. years, she explored various computer architectures with her adviser, Michael Flynn, and her second reader, John Hennessy, respectively giants in Complex Instruction Set Computer (CISC) and the then emerging Reduced Instruction Set Computer (RISC) architectures, making Ruby an early expert in blending the best of competing genres of instruction-set architectures, which she has described as the “native language” of computers. 

Following her graduation in 1980, Ruby was appointed an acting assistant professor of electrical engineering at Stanford. She then received an exciting job offer to design a new computer architecture at HP, which she joined in fall 1981. A very select, small team was commissioned by the company to design a new computer architecture to unify and advance all three of HP’s main computer product families: the business computers, the high-performance technical workstations, and the factory-floor controllers, with the goals of providing leverage of common hardware, flexibility for differentiation in very different markets, and architectural longevity. The resulting PA-RISC (Precision Architecture Reduced Instruction Set Computer) achieved all these goals, shipping world-wide for several decades. PA-RISC had many futuristic architectural features, including very large address spaces, efficient protection features, and flexible support for new instruction set extensions. Ruby was granted many US and international patents for her work in PA-RISC architecture and implementations. Joel Birnbaum, the director of HP Labs and a senior vice president at HP, has called Ruby “one of the best instruction-set architects in the world.” 

Among other noteworthy achievements at HP, Ruby was the lead hardware designer of the first single-chip CMOS PA-RISC microprocessor, the microprocessor project manager for the second CMOS PA-RISC processor, and a contributor to the design definition for several generations of PA-RISC processors, from low-cost designs to the highest-performing processors in the computer industry. As a chief architect at HP from 1992 until 1998, she oversaw the design and implementation of the first multimedia desktops with real-time software MPEG video and video-conferencing, which hadn’t been considered feasible. To facilitate it, Ruby designed the first multimedia acceleration instructions for microprocessors. These were implemented in PA-RISC processors, then in both the Intel 64-bit x86 microprocessors and the Itanium processors. Similar multimedia “subword-parallel” instructions (SIMD instructions) were implemented in all major instruction-set architectures within five years. These facilitated more expressive human-machine interactions through ubiquitous audio, video, images, and animations, in addition to text. Ruby also formed the first security architecture team at HP and defined a security technology roadmap for the company. 

Concurrent with her industry work, Stanford appointed Ruby a consulting associate professor of electrical engineering from 1989 to 1995, and later a consulting professor of electrical engineering from 1995 to 1998. In this capacity she taught and mentored students who would later become leaders in technology. 

At Princeton, Ruby focused mainly on her new passion for security architecture while also working on processor architecture and multimedia architecture. She established the Princeton Architecture Laboratory for Multimedia and Security (PALMS). She wanted to design security into the foundations of computers and was a pioneer in defining security architecture at the hardware level. For example, she created architecture to provide secure execution environments for trusted software modules so that they could run simultaneously on the same processor with untrusted software — even with untrusted or compromised operating systems or hypervisors. Her research has seen adoption in today’s Trusted Execution Environments (TEEs) in security products such as Trustzone in Arm processors and secure enclaves in Intel processors.  

Another important line of research for which Ruby is well-known is her creative design of secure cache memories that are resilient to cache side-channel attacks. Some of her secure caches defied cache design rules that have been taught for decades, yet her designs achieve all of the required cache functions and can achieve security without degrading performance. In some cases, her secure caches improve both security and performance, a goal previously thought infeasible. Her research also demonstrated practical attacks on the last-level cache memories in cloud computing environments, and her team created important concepts like efficient “eviction sets,” which have stimulated new lines of research in hardware and in algorithms, for both attacks and defenses. 

Her most recent research is in using deep learning to improve the security of computer systems, from power-grid controllers to cloud computing servers to smartphones. Her team has also shown new attacks on deep learning and proposed mitigations for them. 

Ruby also created innovative permutation instructions that could efficiently manipulate bits and sub-words in word-oriented processors. These are very useful for accelerating cryptographic operations and multimedia computations, and newer artificial intelligence algorithms, and have been adopted by Intel and others. 

In her research, Ruby has advocated for a clean-slate approach, rethinking the processor architectures and hardware from scratch to meet the new computing demands or to ensure security of the designs. She has also demonstrated that important security features can be added with minimal impact to the current computing architectures and ecosystems, to encourage earlier adoption by the industry. She is best known for her earlier work on processor and multimedia architecture designs, and her later work on computer security, especially on trusted execution environments and various types of secure processor cache designs. 

She was eager to explore all different levels of computer systems in her research, and published works on multimedia and security considering all levels of computer systems, from processor microarchitectures to cloud-based data centers and mobile devices. She was a prolific speaker and her presence was highly regarded at computer architecture conferences. As one of the first faculty exploring computer architecture and security, she paved the path for other researchers to contribute to this important research field. 

Ruby maintained a vibrant research group, always being actively involved in the research and its dissemination through papers, books, and talks. Her group was very effective, benefiting from her ability to channel her management skills from her past industry roles. With her students, she has published hundreds of research papers, including in top computer architecture, computer security, and Artificial Intelligence conferences. She has also authored a first-of-its-kind book, Security Basics for Computer Architects (Morgan & Claypool, 2013), and contributed chapters to other books, such as Secure Cloud Computing (Springer Science & Business Media, 2014). 

As a pioneer in hardware security research, Ruby has founded hardware security workshops and conferences, such as the Hardware and Architectural support for Security and Privacy (HASP, since 2012) and the Institute of Electrical and Electronics Engineers (IEEE) International Symposium on Secure and Private Execution Environment Design (SEED, since 2021). She has also held several very well-received tutorials on hardware security to introduce both the computer architecture and the security research communities to new issues and opportunities in hardware security. Ruby has held leadership roles in the academic publications IEEE Micro, IEEE Transactions on Computers, IEEE Transactions on Cloud Computing, and the Association for Computing Machinery (ACM) Transactions on Embedded Computing Systems. 

She has been a highly regarded keynote speaker at many domestic and international conferences, and has been invited as a visiting professor at Stanford, Imperial College London, and at the National University of Singapore. 

Ruby has also served on national committees to improve cybersecurity and co-authored reports to the White House, government agencies, and Congress that helped to increase awareness for cybersecurity and funding for security research. 

Ruby was extensively involved in teaching and mentoring at Princeton. She has taught undergraduate courses like “Cyber Security,” “Smartphone Security and Architecture,” and “Computer Architecture,” and graduate courses like “Processor Architectures for New Paradigms,” “Trustworthy Computing,” and “Secure Computers.” She loves to teach new topics and often integrates the latest research. She has also enjoyed interdisciplinary team teaching in courses like “Multimedia and its Impact in the Next Millennium” and “Human Identity in the Age of Neuroscience and Information Technology.” 

Ruby was also selected as a featured faculty innovator at the 2015 and 2021 Celebrate Princeton Innovation events, attesting to the potential impact of her research on the world at large. Her graduate students have gone on to professorial careers at universities, to start security companies, and to lead design or consulting teams at major companies. She has also been recognized as a computer pioneer and interviewed by the Computer History Museum. 

On diversity issues, Ruby represented Princeton with President Harold T. Shapiro at the historic conference held by the MIT President for university presidents and their selected senior women faculty regarding the small number of women faculty in science and engineering, especially in the senior ranks. She was also on the President’s committee that later reviewed the status of women faculty at Princeton University. Ruby also has some interesting diversity “firsts” in her career: She was the first female Ph.D. student to have a baby in Stanford’s Electrical Engineering Department and School of Engineering. At HP, she was the first female chief architect in computer systems. At Princeton, Ruby was the first female endowed chair professor in the School of Engineering and Applied Science. 

Internationally recognized, Ruby was elected to the American Academy of Arts and Sciences in 2020 for her pioneering hardware security research at Princeton and her innovations in processor and multimedia architecture. She was elected an ACM fellow in 2001“for pioneering multimedia instructions in general-purpose processor architecture and innovations in the design and implementation of the instruction set architecture of RISC processors” and an IEEE fellow in 2002 “for contributions to general purpose processor architectures.” She is also a member of the Phi Beta Kappa, Alpha Lambda Delta, and Sigma Xi honorary societies. We will miss Ruby in the department, but her leadership in designing security in fundamental computer architecture will likely continue to inspire future research and products in this important area to improve cybersecurity. 

Written by members of the Department of Electrical and Computer Engineering faculty.