Key-Ladder Chained Certificates for Computing Device Attestation
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Solution Overview
Problem
The DICE Open profile scheme for remote attestation is vulnerable to key leakage and compromise, requiring specific hardware and software support, and necessitates reporting all UDS certificates, compromising security and scalability.
Innovation Solution
A method using a key ladder to generate N chained certificates, where each certificate includes an authentication tag, and device-specific data is encrypted with a UDS-derived key, ensuring robustness against attacks by requiring attackers to compromise both the UDS and key ladder implementation details.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the DICE Open profile scheme is used for remote attestation, then device authenticity can be verified through certificate chains, but the system becomes vulnerable to key leakage and compromise
Solution Approach 1:
The patent segments the authentication process into multiple independent certificate levels (L1, L2, ..., LN), where each level has its own key pair and certificate. This segmentation ensures that compromise at one level does not automatically compromise other levels, as each level's private key is derived independently through its own key ladder process with different input data
Solution Approach 2:
The patent introduces a hierarchical dimension to the authentication system by creating multiple certificate levels stacked vertically. Each level operates in its own security dimension with separate key pairs, allowing the system to verify authenticity across multiple dimensions while isolating key compromise to specific dimensional layers
2Reliability
If all UDS certificates are reported for validation, then complete authentication verification is achieved, but security and scalability are compromised
Solution Approach 1:
The patent extracts the UDS certificate reporting requirement from the authentication process. Instead of requiring all devices to report their UDS certificates, the system only requires reporting of higher-level certificates (L2 and above) that are derived from the UDS but do not expose it. The UDS certificate itself remains private and unreported
Solution Approach 2:
The patent introduces intermediate certificates (L2, L3, ..., LN) as mediators between the UDS and the final authentication verification. These intermediate certificates serve as proxies that provide verification capability without exposing the underlying UDS, allowing complete authentication verification while maintaining security and scalability
3Reliability
If specific hardware and software support is required for DICE, then attestation functionality is enabled, but device complexity increases
Solution Approach 1:
The patent makes the key ladder mechanism universal by designing it to work with existing hardware security modules and key derivation functions already present in modern devices. The same key ladder approach can be applied across different device types and security architectures, eliminating the need for specialized DICE hardware while maintaining attestation functionality
Data Source
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AI summary
The method includes the steps performed by a first computing device provisioned with a unique device secret, UDS, of generating an N chained certificate[s] attesting the authenticity of an N set[s] of device-specific data (Di) of the first computing device, and transmitting the N chained certificate[s] to a second computing device. The step of generating the N chained certificate[s] comprises a generation process that includes: A. deriving, using a key ladder, a key from the UDS; B. generating an authentication tag from a set of device-specific data, using the key; C. generating a certificate, said certificate including the set of device-specific data and the authentication tag; D. encrypting the set of device-specific data with the key; and E. providing the encrypted set of device-specific data as an input to the key ladder for a subsequent generation process.