Hardware-Identified Key Store Access for Compromised Firmware
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Solution Overview
Problem
Existing security solutions for integrated circuits (ICs) fail to prevent unauthorized access to keys when firmware is compromised, as identifiers used for key access can be exploited, and keys derived from compromised firmware can be misused or decoded, compromising key confidentiality.
Innovation Solution
A key store system that utilizes hardware identifiers to control access, enforces hardware protected modes for high-security keys, and restricts key usage to hardware-only operations, preventing unauthorized access and misuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If identifiers are used for key access control, then key accessibility is improved, but security is worsened when firmware is compromised
Solution Approach 1:
The patent segments key access control into multiple hierarchical levels: hardware identifiers for basic access, firmware identifiers for derived key access, and hardware protected modes for high-security keys. This segmentation ensures that compromise at one level does not automatically grant access to all keys, as different identifier types and protection modes create isolated security zones.
Solution Approach 2:
The patent introduces hardware protected modes as an intermediary layer between firmware and high-security keys. This intermediary prevents direct access to sensitive keys by requiring additional hardware-enforced authentication steps, so even if firmware is compromised, the intermediary block prevents unauthorized key access.
2Adaptability or versatility
If keys are derived from firmware, then key functionality is improved, but key confidentiality is worsened when firmware is compromised
Solution Approach 1:
The patent implements dynamic key derivation where the security properties of derived keys adapt based on the security mode of the parent key. High-security parent keys automatically enforce hardware protected modes on derived keys, while standard keys use firmware identifiers. This dynamic adaptation ensures key confidentiality is maintained proportionally to the parent key's security level.
Solution Approach 2:
The patent changes the security parameters of derived keys based on their parent key's classification. When a high-security key is used for derivation, the resulting key inherits enhanced parameters including hardware protected mode requirements and restricted access policies, thereby maintaining confidentiality even as key functionality expands.
3Reliability
If hardware protected modes are enforced, then key security is improved, but device complexity is worsened
Solution Approach 1:
The patent creates a universal hardware protected mode framework that serves multiple security functions: access control enforcement, key derivation protection, and firmware authentication. This multi-functional approach consolidates what could be separate complex systems into a single unified mechanism, reducing overall system complexity while maintaining high security standards.
Data Source
AI summary
A computing system or an integrated circuit includes a key storage circuit for storing a key and an access control enforcer circuit that grants access to the key stored in the key storage circuit in response to receiving a request based on a hardware identifier that identifies a hardware system and a subcomponent of the hardware system that is an owner of the key. The access control enforcer circuit accesses a hardware property for a key from an access control attributes circuit in response to a request to access the key. The access control enforcer circuit prevents the key from being returned to an initiator of the request if the hardware property indicates that the key is protected. The access control enforcer circuit permits the key to be used to derive, wrap, or unwrap other keys if the hardware property indicates that the key is protected.