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Trust Bridges: Secure Information Sharing Across Independent Domains

Introduction to Trust Bridges

Trust bridges are mechanisms that enable the secure sharing of information between two independent trust domains. They can facilitate sharing between trust domains with differing security and operating policies, and support bridging between trust domains that rely on different frameworks, such as X.509 and IEEE 1609.2.

The concept of a trust bridge is to enable secure sharing of information across independent trust domains. A trust bridge ensures that data integrity, confidentiality, and authenticity are preserved throughout the transfer, even when bridging involves proprietary systems.

What a Trust Bridge Can Support

  1. Bridges Security Frameworks
    Trust bridges allow secure communication between trust domains that rely on disparate security frameworks.
  2. Example: An ITS Station configured with an X.509 certificate may need to communicate with a vehicle configured with IEEE Std. 1609.2 certificates.

  3. A trust bridge can validate message content using one framework and re-sign the content using a different framework.

  4. Facilitate Secure Interoperability
    Trust bridges can act as intermediaries between different policy domains, ensuring secure and consistent communication.

  5. End-to-End Security
    Trust bridges support end-to-end authentication by ensuring messages remain tamper-proof and verifiable from source to destination.

  6. Support Interactions with Proprietary Systems
    Trust bridges enable integration of proprietary systems by securely forwarding communications from a public domain to a proprietary domain.

Attributes of a Trust Bridge

A trust bridge should be designed and developed to mitigate the cybersecurity risks faced by all domains it interacts with. Without these safeguards, the trust bridge risks becoming a weak link in the system's security. Key attributes of a trust bridge include:

  1. Tamper Resistance
    Trust bridges should be resistant to both physical and electronic tampering.

  2. End-to-End Authentication Preservation
    Trust bridges must maintain message authenticity across bridged domains, ensuring data integrity and trust.

  3. Auditable
    Trust bridges should maintain detailed event logs for tracking and auditing communication events.

Applications of Trust Bridges in ITS

  1. Inter-Domain Communications
    Trust bridges can secure information flows between Traffic Management Centers (TMCs) and proprietary systems, ensuring that critical data is exchanged securely and reliably.