Security Module Key Derivation With Runtime Fingerprints
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Solution Overview
Problem
Existing trust anchors in data processing systems, such as TPMs, are vulnerable to attacks when attackers exploit software weaknesses, allowing derived cryptographic keys to be reconstructed, leading to insufficient protection.
Innovation Solution
Incorporate a changeable digital fingerprint based on the measurable current runtime configuration of the environment into the key derivation process, ensuring keys are derived dynamically and change with system manipulations, using a one-way function to enhance security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If static key derivation based on fixed properties is used, then key generation is simple and deterministic, but security is insufficient against attackers who exploit software weaknesses
Solution Approach 1:
The patent transforms static key derivation into a dynamic process by incorporating runtime configuration measurements (fingerprint) as input to the key derivation function. The fingerprint changes based on the actual runtime state of the system, making the derived keys dynamic rather than static. This resolves the contradiction by adding temporal variability to enhance security while maintaining a relatively simple derivation mechanism.
Solution Approach 2:
The patent changes the input parameters of the key derivation function from fixed static properties to dynamic runtime measurements. By using measurements of the actual runtime configuration (such as memory contents, register states, or other system state indicators) as the fingerprint input, the key derivation process incorporates real-time system state, thereby enhancing security against attacks that exploit static weaknesses.
2Reliability
If keys are derived from static properties, then key derivation is fast and deterministic, but derived keys can be reconstructed by attackers who gain control of the system
Solution Approach 1:
The patent makes key derivation dynamic by incorporating runtime fingerprint measurements. Each key derivation now depends on the current runtime state of the system, which changes over time. This prevents attackers from reconstructing keys even if they gain control at different times, because the fingerprint (and thus the derived key) will be different for each runtime state.
Solution Approach 2:
The patent introduces a fingerprint measurement as an intermediary between the static master key and the derived keys. This intermediary captures the dynamic runtime state and feeds it into the key derivation function, creating a bridge between static key material and dynamic security requirements. The fingerprint acts as a mediator that ensures derived keys reflect the actual runtime environment.
3Device complexity
If a single master key is used for all derivations, then key management is simple, but all derived keys remain vulnerable if the master key is compromised
Solution Approach 1:
The patent segments the key derivation process by introducing the fingerprint as a separate, independent input alongside the master key. Instead of deriving all keys from a single master key in isolation, the system now segments key derivation into multiple inputs: the static master key and the dynamic fingerprint. This segmentation ensures that compromise of one component (master key) does not automatically compromise all derived keys, as the fingerprint provides an additional layer of protection.
Solution Approach 2:
By incorporating the dynamic fingerprint into the key derivation process, the patent creates time-varying derived keys even when using a single master key. The derived keys become functions of both the master key and the current runtime state, meaning that keys derived at different times or under different runtime conditions will differ. This dynamic approach mitigates the risk of master key compromise.
Data Source
AI summary
Provided is a method for configuring a security module with at least one derived key, having the following steps: providing a key; deriving a further key from the provided key or from a key previously derived from the provided key, wherein the further key is derived by using an alterable digital fingerprint as key derivation parameter, which is formed on the basis of a measurable current runtime configuration of a runtime environment communicating with the security module.