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PCIe is the primary high-speed interconnect used to connect processors with accelerators, memory devices, storage, and networking components. It provides a common and scalable foundation for moving large volumes of data between the compute and I/O resources that make up a modern system. As architectures add more powerful accelerators and higher-performance devices, PCIe continues to evolve to deliver greater bandwidth while maintaining low latency and broad ecosystem interoperability. These capabilities have made it essential to data center, AI, cloud, networking, storage, and other performance-intensive systems. PCIe security is no longer optional As PCIe links carry increasingly sensitive workloads, protecting data in motion has become as important as bandwidth, latency, and interoperability. Data moving between processors, accelerators, memory devices, storage subsystems, and network adapters must be protected against interception, tampering, and replay attacks, particularly in AI training, confidential computing, cloud infrastructure, and high-performance data processing. The PCIe specification defines Integrity and Data Encryption (IDE) as the standard for securing data across a PCIe link. IDE protects Transaction Layer Packets with confidentiality, integrity, and replay protection as they travel between connected components. Bifurcation is becoming more common A growing trend to support more devices and make better use of available lanes is PCIe bifurcation, which divides a single wider interface into multiple independent links. For example, a PCIe x16 interface can be configured as two x8 links, four x4 links, or a combination such as x8 + x4 + x2 + x2. The total lane count remains unchanged, but those lanes form more independent connections. Bifurcation gives system designers greater flexibility, improves lane utilization, supports multiple endpoints, and enables reduced resource usage. That flexibility also changes the security model: one x16 link is not equivalent to four separate links because each independent connection requires its own IDE protection, as illustrated in the figure below. This creates an implementation challenge for traditional architectures, which typically dedicate IDE resources to each PCIe controller or port. As the number of independent links grows, designers may need additional encryption engines and management logic, increasing silicon area, power, and design complexity. Why traditional IDE architectures become inefficient With bifurcation increasing the number of links, designers often find themselves replicating encryption engines, management logic, and supporting security infrastructure. This approach introduces several challenges, such as:

• Area growth: Each additional protected link requires additional hardware resources. As the number of links scales, area consumption can grow significantly.
• Floorplanning complexity: Security logic must often be placed close to individual controllers, creating congestion and making physical implementation more difficult.
• Scalability limitations: Security resources scale in proportion to controller count rather than actual throughput requirements. This can produce inefficiencies in highly bifurcated designs.

The result is an architecture where security becomes a scaling bottleneck. Designers gain flexibility through bifurcation but pay for it through duplicated security hardware. Enter Shared IDE Shared IDE takes a different approach. Instead of duplicating IDE resources for every PCIe controller, Shared IDE (as shown in the earlier diagram) allows multiple controllers and links to utilize a common security infrastructure while maintaining independent protection mechanisms. This fundamentally changes the scaling model. Rather than tying security resource growth directly to the number of ports, Shared IDE enables security resources to be shared across multiple interfaces, reducing duplication without compromising standards compliance. The approach offers three primary benefits:

• Lower cost and area: By eliminating unnecessary duplication, Shared IDE can reduce overall hardware requirements. This leads to fewer replicated security blocks, lower silicon area, and improved power efficiency.
• Greater design flexibility: Shared IDE can be physically separated from PCIe controllers and PHYs, giving implementation teams more freedom during floorplanning, which helps to reduce congestion and facilitates easier timing closure.
• Security without compromise: Importantly, sharing resources does not mean sharing security contexts. Each port retains independent protection, dedicated security contexts, separate key management, and standards-aligned PCIe IDE compliance. This means security remains isolated even while implementation resources are shared.

Therefore, the shared infrastructure performs common processing tasks while preserving logical separation between protected connections. In other words, a good Shared IDE implementation reduces overhead without reducing trust. The concept is specifically developed so that security scaling becomes independent of controller scaling. This distinction is important because future PCIe systems are expected to continue increasing both performance and connectivity. Security architectures that depend on linear duplication will become increasingly difficult to justify from both cost and implementation complexity perspectives. Shared IDE for high-performance PCIe Rambus has implemented this Shared IDE approach in a production-ready architecture designed specifically for high-performance PCIe systems. The Rambus Shared IDE solution enables multiple PCIe controllers and links to use a common security infrastructure while maintaining an independent security context for each port. Because PCIe traffic is packetized, the architecture can arbitrate traffic and dynamically process transport-layer packets from multiple controllers without requiring a dedicated cryptographic engine for every connection. The solution combines high-throughput AES-GCM and SM4-GCM processing with a Shared IDE wrapper, segmented bus architecture, dynamic bandwidth allocation, and support for bifurcated PCIe configurations. Its centralized management and configurable pipeline stages simplify integration while preserving the integrity, isolation, and standards alignment required by PCIe IDE. The main benefits of the solution include:

• Improved PPA: Shared processing reduces duplicated security hardware, with potential gate-count reductions of up to ~1.5x compared with traditional approaches.
• Better floorplanning: Security blocks can be placed independently of controllers and PHYs, reducing congestion in critical design regions.
• Bifurcation-friendly scaling: Security resource requirements do not need to increase in direct proportion to the number of protected links.
• Flexible, standards-aligned integration: Configurable deployment options support different architectures while maintaining independent protection for each port.

Looking ahead: Security architectures must scale smarter PCIe bifurcation is becoming a standard design technique because it increases flexibility and enables better utilization of available bandwidth. At the same time, IDE adoption is expanding as organizations seek stronger protection for data in motion. Unfortunately, traditional security architectures were never designed for a world where link counts grow faster than lane counts. Shared IDE addresses this challenge by decoupling security scaling from controller scaling. Instead of replicating security resources every time a design introduces additional protected links, a shared architecture enables multiple interfaces to leverage common security infrastructure while preserving independent protection. For SoC architects, this means lower area, reduced implementation complexity, better floorplanning flexibility, and a more scalable path to future PCIe generations. For companies building next-generation AI, cloud, networking, storage, and data center platforms, Shared IDE represents a smarter way to scale trust. By combining efficient resource utilization with standards-aligned protection, the Rambus Shared IDE solution helps designers build secure bifurcated PCIe systems that are ready for the performance and connectivity demands of tomorrow. The post Shared IDE For PCIe Bifurcation: Scaling Security Without Scaling Complexity & Resources appeared first on Semiconductor Engineering.

Source: https://semiengineering.com/shared-ide- ... resources/