Gateway XMSS Remote Attestation for Autonomous Microcontrollers
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Solution Overview
Problem
Existing public-key digital signature algorithms such as RSA and ECDSA are vulnerable to brute-force attacks from quantum computers, necessitating the development of post-quantum cryptography solutions, particularly hash-based signatures like XMSS and LMS, which require robust state synchronization and single-use guarantees for private keys to maintain security.
Innovation Solution
Implementing a system where resource-constrained microcontrollers in autonomous systems use a gateway device to manage XMSS state and perform signature operations, ensuring single-use of private keys and enabling efficient post-quantum secure attestation through a gateway device that orchestrates with other compute nodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hash-based signature schemes (XMSS, LMS) are implemented on resource-constrained microcontrollers, then post-quantum security is achieved, but computational overhead and memory requirements increase
Solution Approach 1:
The system is divided into two parts: a gateway device that performs computationally intensive XMSS state management and signature operations, and resource-constrained microcontrollers that only need to verify signatures. This segmentation allows post-quantum security to be implemented without burdening the limited hardware resources of the microcontrollers.
Solution Approach 2:
The gateway device acts as an intermediary between the microcontrollers and the post-quantum signature verification process. It manages the XMSS private key, generates signatures, and handles state synchronization, thereby shielding the resource-constrained microcontrollers from the computational complexity of hash-based signatures.
2Extent of automation
If XMSS state is managed locally on each microcontroller, then autonomy is maintained, but state synchronization and security guarantees become difficult
Solution Approach 1:
The gateway device serves as a central intermediary that maintains the master XMSS state and synchronizes it with all microcontrollers. This ensures that all nodes in the autonomous system share the same cryptographic state without requiring complex peer-to-peer synchronization protocols.
Solution Approach 2:
The gateway device performs multiple functions: it acts as a certificate authority, manages XMSS state, generates signatures for all microcontrollers, and handles key rotation. This centralized multi-functional approach simplifies the architecture compared to distributed state management.
3Productivity
If private keys are reused across multiple signature operations, then operational efficiency increases, but security is compromised
Solution Approach 1:
The XMSS scheme uses a dynamic state management approach where the gateway device tracks which leaf nodes in the Merkle tree have been used for signing. The system automatically transitions from used leaves to fresh leaves, ensuring each private key component is used only once while maintaining efficient signature generation through pre-computed Merkle authentication paths.
Data Source
Figure 1A~1B
Figure 2A
Figure 2B
AI summary
A method comprises maintaining, for at least one remote device, a security footprint and a verified version of a software stack for the remote device, generating an attestation initiation token that includes a nonce to be used to generate an XMSS signature for attestation of the remote device, sending the attestation initiation token to the remote device, receiving, from the remote device, a modified message representative including a hash of a current version of a software stack for the remote device and an indicator of a version number of the current version of the software stack for the remote device, validating the hash, and in response to a determination that the hash is valid, generating an XMSS signature using the security footprint and the current version of a software stack for the remote device and a security footprint for the apparatus.