Trust Dependency Management in Trusted Platform Modules

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Solution Overview

Problem

Current Trusted Computing Group standards do not effectively address trust dependencies among components in computer systems, which are crucial for ensuring the integrity and confidentiality of code and data, particularly in systems with multiple Trusted Building Blocks.

Innovation Solution

A method is introduced to define and resolve trust dependency relationships among components by identifying trust-determinant components and Platform Configuration Registers (PCRs) within the Trusted Platform Module (TPM), allowing for the computation of integrity measurements and attestation processes, enabling operations such as generating attestation replies and sealing/unsealing data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If current TCG standards are used without trust dependency support, then the system structure remains simple, but the ability to ensure integrity and confidentiality across multiple Trusted Building Blocks is insufficient

Engineering Contradiction:

Improveintegrity and confidentiality assuranceVSAvoidsystem structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the trust evaluation process by introducing separate trust dependency relationship definitions and resolutions. Each Trusted Building Block has its own set of trust dependencies that are independently managed through PCR trust dependency relationships, allowing modular evaluation of integrity and confidentiality across multiple components without requiring complete system redesign

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces Platform Configuration Registers (PCRs) as intermediaries to manage trust dependencies. PCRs serve as mediators that store trust dependency relationships and enable the evaluation of integrity and confidentiality without direct complex interactions between all Trusted Building Blocks, simplifying the overall system structure while maintaining reliability

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If trust dependency relationships are defined and resolved among components, then the security and integrity of the system is enhanced, but the complexity of managing trust relationships increases

Engineering Contradiction:

Improvesecurity and integrityVSAvoidtrust relationship management

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent makes PCRs universal by enabling them to serve multiple functions: storing integrity measurements, managing trust dependency relationships, and facilitating both attestation and sealing operations. This multi-functionality reduces the need for separate dedicated structures for trust management, thereby enhancing security without proportionally increasing complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent performs preliminary actions by pre-defining trust dependency relationships between components and pre-establishing PCR mappings before actual security operations occur. This allows the system to efficiently resolve trust dependencies during runtime without requiring complex real-time analysis, thus enhancing security while keeping management complexity manageable

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If multiple Trusted Building Blocks with trust dependencies are implemented, then the system can provide finer-grained security control, but the difficulty of detecting and measuring trust relationships increases

Engineering Contradiction:

Improvesecurity control granularityVSAvoidtrust relationship detection

Core Design Contradiction:

Adaptability or versatilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent replaces complex mechanical tracking of trust relationships with cryptographic measurement mechanisms. Instead of manually detecting and measuring trust dependencies, the system uses PCR values and integrity measurements to automatically verify trust relationships, making the detection and measurement process simpler while enabling finer-grained security control

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements feedback mechanisms where the system continuously monitors and verifies trust dependency relationships through PCR readings and integrity measurements. This feedback allows the system to detect changes in trust relationships and adjust security controls accordingly, providing fine-grained adaptability while keeping detection straightforward through automated verification

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS8037318B2System and methods for dependent trust in a computer system

Publication Date: 2011.10.11 ORACLE AMERICAN INC

AI summary

A method for dependent trust in a computer system is provided. In this method, trust dependency relationships are defined among components of the computer system, specifying, for a component, which components it relies on in ensuring the integrity or confidentiality of its code or data. Subsequently, trust dependencies are resolved and the results are used in performing certain operations described in Trusted Computing Group standards including generating an attestation reply, sealing data, and unsealing data. In addition, methods for computing an integrity measurement for a Core Root of Trust for Measurement of a trust-dependent component are included. A system for dependent trust in a computer system is also described.