Block Integrated Trust (BIT)

Mission

The Block Integrated Trust (BIT) Work Group, formerly known as Measurement and Attestation Roots (MARS), within the Trusted Computing Group (TCG) is dedicated to extending the Root of Trust architecture to embedded components and peripheral subsystems, such as IoT devices, microcontrollers, sensors, and other integrated circuits. Its core mission is to enable a standardized, scalable architecture that allows deeply embedded and resource-constrained components to establish cryptographically verifiable identities, protect critical data, and report their health, even when they lack separate, adjunct security hardware due to power, manufacturing processes, space, and cost.

What the group does

The BIT Work Group develops specifications, APIs, and guidance for on-chip, integrated primitives that support measurement, attestation, and secure storage in constrained silicon environments. The group defines end-to-end solutions optimized for lightweight symmetric cryptography, intentionally designed to be implemented as immutable hardware state machines using pure logic to ensure compatibility with a vast range of manufacturing processes. This includes standardizing programming interfaces like Memory-Mapped I/O (MMIO) and command serialization over I2C, SPI, or CAN interfaces using CBOR encoding. A major focus of the Work Group is the development of a comprehensive Symmetric Attestation and Chain of Custody protocol, which utilizes a two-tiered deterministic key hierarchy (Primary Seed and Derivation Parents) to securely manage and cryptographically record the logical transfer of hardware custodianship as components progress through the supply chain.

Why it matters

As the digital ecosystem expands, trust must be anchored not just in main CPUs, but in the myriad of embedded peripheral subsystems, edge IoT devices, and sensors that make up a modern platform. Because these micro-components are often too constrained to support complex asymmetric cryptography (like RSA/ECC) or dedicated security microcontrollers, they present critical vulnerabilities. BIT addresses this by providing a highly optimized, low-footprint hardware Root of Trust. This enables critical defense-in-depth capabilities such as anti-counterfeiting verification, remote attestation of boot health, sealed storage, and secure firmware updates for the absolute smallest of chips. BIT can be used to guarantee supply-chain transparency, prevent the use of counterfeit hardware, and ensure that zero trust architectures can extend all the way down to the peripheral silicon level.

Who participates

Participants in the BIT Work Group include domain experts in embedded device architectures, hardware design, silicon manufacturing, and cryptography. Key demographic representation includes silicon manufacturers, Intellectual Property (IP) block vendors, Original Design Manufacturers (ODMs), Original Equipment Manufacturers (OEMs), and enterprise platform owners. The group collaborates closely with external standard development organizations like the IETF (specifically aligning with the RATS architecture) and SAE International. Internally, the Work Group works alongside other TCG Work Groups, including Vehicle Services, IoT, DICE, TPM, and Infrastructure, to ensure broad interoperability across the automotive, enterprise, and industrial sectors.

Key deliverables

• BIT Library Specification: Defines the core implementation of BIT commands, required cryptographic primitives, and a standard C library API.
• BIT Command Serialization Specification: Details how to format and transmit BIT commands over common peripheral interfaces (e.g., I2C, SPI, CAN) using lightweight CBOR encoding.
• Hardware Reference Implementation: An open, informative hardware reference implementation of the BIT IP-block.
• Profile Guidance and Emulators: Informative source code, hardware emulators, CDDL (Concise Data Definition Language) models, and deployment guidance covering use cases like anti-counterfeiting, verified boot, and update protection.
• In Development: Specifications covering native Memory-Mapped I/O (MMIO) interfaces and a standardized Symmetric Attestation and Chain of Custody Protocol.

Technology the group develops

The BIT Work Group develops the Block Integrated Trust (BIT) architecture and its supporting ecosystem. This includes mechanisms for deterministic device identity generation, snapshot-based device measurement (via Trusted Sensor Registers and PCRs), and layered symmetric attestation. The group also pioneers TCG's logical Chain of Custody technology, allowing verifiable ownership transfers without ever exposing foundational root secrets. BIT is designed to interoperate securely with the broader TCG ecosystem, extending TCG's Root of Trust architecture to embedded components and peripheral subsystems.