Split Manufacturing Research Articles

Obfuscated Built-In Self-Authentication With Secure and Efficient Wire-Lifting

Hardware Trojan insertion and intellectual property (IP) theft are two major concerns when dealing with untrusted foundries. Most existing mitigation techniques are limited in protecting against both vulnerabilities. Split manufacturing is designed to stop IP piracy and integrated circuit (IC) cloning, but it fails at preventing untargeted hardware Trojan insertion and incurs significant overheads when high level of security is demanded. Built-in self-authentication (BISA) is a low-cost technique for preventing and detecting hardware Trojan insertion, but is vulnerable to IP piracy, IC cloning, or redesign attacks, especially on original circuitry. In this paper, we propose an obfuscated BISA technique that combines and optimizes both the techniques so that they complement and improve security against both vulnerabilities, while at the same time minimizing design overheads to the extent that the proposed method does not incur prohibitive cost for designs of industrial-level sophistication. Our evaluation on advanced encryption standard and data encryption standard cores shows that the proposed technique can reach security levels more than two times higher, satisfying all existing layout-based security metrics, while reducing overheads from hundreds of percents to less than 13% in power, 5% in delay, and zero percent in area, as compared to best reported performance in existing techniques.

A Practical Split Manufacturing Framework for Trojan Prevention via Simultaneous Wire Lifting and Cell Insertion

Trojans and backdoors inserted by untrusted foundries have become serious threats to hardware security. Split manufacturing is proposed to hide important circuit structures and prevent Trojan insertion by fabricating partial interconnections in trusted foundries. Existing split manufacturing frameworks, however, usually lack security guarantee and suffer from poor scalability. It is observed that inserting dummy cells and wires can have high potential on overcoming the security and scalability problems of existing methods, but it is not compatible with current security definition. In this paper, we focus on answering the questions on how to define the notion of security and how to realize the required security level effectively and efficiently when the insertion of dummy cells and wires is considered. We first generalize existing security criterion by modeling the split manufacturing process as a graph problem. Then, a sufficient condition is derived for the proposed security criterion to avoid the computationally intensive operations in traditional methods. To further enhance the scalability of the framework, we propose a secure-by-construction split manufacturing flow. For the first time, a novel mixed-integer linear programming (MILP) formulation is proposed to simultaneously consider cell and wire insertion together with wire lifting. A Lagrangian relaxation algorithm with a minimum-cost flow transformation technique is employed to solve the MILP formulation efficiently. With extensive experiments, our framework demonstrates significantly better efficiency, overhead reduction, and security guarantee compared with the previous state-of-the-art.

Split Manufacturing-Based Register Transfer-Level Obfuscation

Fabrication-less integrated circuit (IC) design houses outsource fabrication to third-party foundries to reduce cost of manufacturing. The outsourcing of IC fabrication, beyond our expectation, raises concerns regarding intellectual property (IP) piracy and theft by rogue elements in the third-party foundries. Obfuscation techniques have been proposed to increase resistance to reverse engineering, IP recovery, IP theft, and piracy. However, prior work on obfuscation for IP protection has primarily applied to the gate level or the layout level. As a result, it can significantly impact the performance of the original design in addition to requiring redesign of standard cells. In this article, we propose a high-level synthesis and analysis (HLSA)-based obfuscation approach for IP protection. The proposed method is based on split manufacturing. Additional dummy units and MUXes can be added to further obfuscate the design. The proposed technique aligns with the standard-cell-based design methodologies and does not significantly impact the performance of the original design. Our experimental results confirm that the proposed approach can provide high levels of IC obfuscation with moderate area cost.

The Cat and Mouse in Split Manufacturing

Split manufacturing of integrated circuits eliminates vulnerabilities introduced by an untrusted foundry by manufacturing only a part of the target design at an untrusted high-end foundry and the remaining part at a trusted low-end foundry. Most researchers have focused on attack and defenses for hierarchical designs and/or use a relatively high-end trusted foundry, leading to high cost. We propose an attack and defense for split manufacturing for flattened designs. Our attack uses a network-flow model and outperforms previous attacks. We also develop two defense techniques using placement perturbation—one using physical design information and the other using logical information—while considering overhead. The effectiveness of our techniques is demonstrated on benchmark circuits.

Are Proximity Attacks a Threat to the Security of Split Manufacturing of Integrated Circuits?

Split manufacturing is a technique that allows manufacturing the transistor-level and lower metal layers of an integrated circuit (IC) at a high-end, untrusted foundry, while manufacturing only the higher metal layers at a smaller, trusted foundry. Using split manufacturing is only viable if the untrusted foundry cannot reverse engineer the higher metal layer connections (and thus the overall IC design) from the lower layers. This paper studies the effectiveness of proximity attack as a key step to reverse engineer a design at the untrusted foundry. We propose and study different proximity attacks based on how a set of candidates are defined for each broken connection. The attacks use both placement and routing information along with factors which capture the router’s behavior such as per-layer routing congestion. Our studies are based on designs having millions of nets routed across nine metal layers and significant layer-by-layer wire size variation. Our results show that a common, Hamming distance-based proximity attack seldom achieves a match rate over 5%. But our proposed attack yields a relatively small list of candidates which often contains the correct match. Finally, we propose a procedure to artificially insert routing blockages in a design at a desired split level, without causing any area overhead, in order to trick the router to make proximity-based reverse engineering significantly more challenging.

Beyond the Interconnections: Split Manufacturing in RF Designs

With the globalization of the integrated circuit (IC) design flow of chip fabrication, intellectual property (IP) piracy is becoming the main security threat. While most of the protection methods are dedicated for digital circuits, we are trying to protect radio-frequency (RF) designs. For the first time, we applied the split manufacturing method in RF circuit protection. Three different implementation cases are introduced for security and design overhead tradeoffs, i.e., the removal of the top metal layer, the removal of the top two metal layers and the design obfuscation dedicated to RF circuits. We also developed a quantitative security evaluation method to measure the protection level of RF designs under split manufacturing. Finally, a simple Class AB power amplifier and a more sophisticated Class E power amplifier are used for the demonstration through which we prove that: (1) the removal of top metal layer or the top two metal layers can provide high-level protection for RF circuits with a lower request to domestic foundries; (2) the design obfuscation method provides the highest level of circuit protection, though at the cost of design overhead; and (3) split manufacturing may be more suitable for RF designs than for digital circuits, and it can effectively reduce IP piracy in untrusted off-shore foundries.

Hacking with Chinese Characteristics

From the rising number of hackerspaces to an increase in hardware start-ups, maker culture is envisioned as an enabler of the next industrial revolution—a source of unhindered technological innovation, a revamp of broken economies and educational systems. Drawing from long-term ethnographic research, this article examines how China’s makers demarcate Chinese manufacturing as a site of expertise in implementing this vision. China’s makers demonstrate that the future of making—if to materialize in the ways currently envisioned by writers, politicians, and scholars of the global tech industry—rests on taking seriously the technological and cultural fabrics of professional making outside familiar information technology innovation hubs like Silicon Valley: making-do, mass production, and reuse. I trace back to China’s first hackerspace, documenting how a collective of makers began to move away from appropriating Western concepts of openness toward promoting China as source for knowledge, creativity, and innovation. This article demonstrates that when China’s makers set up open hardware businesses and articulate a unique culture of “hacking with Chinese characteristics,” they draw boundaries between the professional making they saw embodied in Chinese industrial production and the hobbyist making embodied in Western histories and cultures of hacking. In so doing, they position China as site of both technological and cultural expertise, intervening in dominant conceptions of computing that split manufacturing and innovation along geographical lines. This article contributes to critical scholarship of innovation and making cultures, technological expertise, and authorship.

Regaining Trust in VLSI Design: Design-for-Trust Techniques

Designers use third-party intellectual property (IP) cores and outsource various steps in their integrated circuit (IC) design flow, including fabrication. As a result, security vulnerabilities have been emerging, forcing IC designers and end-users to reevaluate their trust in hardware. If an attacker gets hold of an unprotected design, attacks such as reverse engineering, insertion of malicious circuits, and IP piracy are possible. In this paper, we shed light on the vulnerabilities in very large scale integration (VLSI) design and fabrication flow, and survey design-for-trust (DfTr) techniques that aim at regaining trust in IC design. We elaborate on four DfTr techniques: logic encryption, split manufacturing, IC camouflaging, and Trojan activation. These techniques have been developed by reusing VLSI test principles.

Improvement of Surface Layer Formation Technology for Articles Produced by Layer-by-Layer Laser Sintering

Mathematical relation between roughness of the surface layer of the sintered article and layer-by-layer laser sintering modes obtained from experiments conducted using copper powder material PMS-1. Authors suggest that split manufacturing process of an article and its inner part must be split to roughing, semi-finishing and finishing modes.

History of Regulatory Requirements for Poultry Biologics in the United States, 1970s to 1990s

By the end of the 1960s, The United States Department of Agriculture (USDA) had established the basic purity and safety standards for poultry biologics in the United States and had licensed products to address many of the major poultry diseases of concern at that time. The emergence of new diseases, advances in scientific technology, and changes in poultry husbandry practices that occurred in the 1970s to the 1990s required the development of many new and amended regulatory requirements to keep abreast of the changing needs of the poultry industry. Veterinary Services often approved the use of special or conditional licensing procedures to shorten the time to license products needed to address emerging diseases. Infectious bronchitis, bursal disease, fowl cholera, duck virus enteritis, avian influenza, and other vaccines were rapidly licensed to address emerging disease problems using this procedure. Changes in labeling and packaging requirements were made to address changing vaccination practices. Veterinary Services permitted diluents to be shipped separate from product, first for Marek's disease vaccine and later for vaccines recommended for administration by automatic vaccinating machines. The maximum number of doses permitted to be in one container and package were also amended to address the increased size of poultry flocks. Veterinary Services also approved the use of split manufacturing procedures that permitted two or more licensed manufacturers to work together in the production of a product. This innovative use of licensing products for further manufacture allowed the industry to use production facilities more efficiently and provided a wider variety of combination products. In 1985, Congress passed an amendment to the Virus-Serum-Toxin Act that gave USDA the authority to regulate all veterinary biological products shipped in or from the United States. This amendment brought intrastate biologics manufacturers under federal jurisdiction and ensured all biological products shipped in or from the United States met the same standards of purity, safety, potency, and efficacy. The development of new recombinant DNA (r-DNA) techniques for the production of vaccines required USDA to establish new procedures and rules for the review of these products prior to their release into the environment and eventual licensure. Compliance with the National Environmental Policy Act required the preparation of environmental risk assessments and public participation in the field testing and licensing of live r-DNA products. This article addresses some of the history of these and other changes in regulatory requirements for poultry products that took place in the 1970s to the 1990s, but space does not permit us to address all of the changes that have occurred. We have presented some of what we consider the most notable events in this process and leave it up to future historians to address events that may not have been included.

A 3-D Split Manufacturing Approach to Trustworthy System Development

Securing the supply chain of integrated circuits is of utmost importance to computer security. In addition to counterfeit microelectronics, the theft or malicious modification of designs in the foundry can result in catastrophic damage to critical systems and large projects. In this letter, we describe a 3-D architecture that splits a design into two separate tiers: one tier that contains critical security functions is manufactured in a trusted foundry; another tier is manufactured in an unsecured foundry. We argue that a split manufacturing approach to hardware trust based on 3-D integration is viable and provides several advantages over other approaches.

Applying forming simulation to process and tooling designs for minimizing springback in split dowel manufacturing

In this study, FEA simulations were conducted to analyze the forming and springback of a split dowel forming process. Through 96 simulations, the best dimensional quality product from the current production tooling was obtained. However, it still cannot meet the customer’s geometrical requirement, so a metal finish process (secondary operation) is required. In order to minimize manufacturing cost and time, the secondary operation is not desired. Therefore, a new forming process and die design were developed through many iterative FEA simulations. This new design adds a short coin bead on the seam line area of the split dowel. It has been found that the springback amount is almost eliminated and the product quality exceeds the customer’s geometry requirement. Through this real industry case study, it is shown that FEA simulation can be used to not only optimize the current process but also design a new process and tooling.