Trusted Platform Module Secure Key Storage
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Solution Overview
Problem
Modern storage media fail to securely and irretrievably delete sensitive information, leading to potential security breaches due to data recovery from magnetic and solid-state storage technologies, and whole volume encryption mechanisms require secure key management during updates and hibernation states.
Innovation Solution
A Trusted Platform Module (TPM) is utilized to store and securely delete keys associated with whole volume encryption mechanisms, ensuring irretrievable removal of sensitive information by generating a protector and storing the unlocking key within the TPM's secure storage, which can be deleted even if the storage medium does not guarantee immediate irretrievable deletion, and access to encrypted data is tied to the computing device's configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is stored on modern storage media (magnetic or solid-state), then data accessibility and storage capacity are improved, but secure deletion capability deteriorates because data marked for deletion remains recoverable for substantial time
Solution Approach 1:
The patent extracts the critical security function (key storage) from the unreliable storage media and places it in the TPM. The TPM becomes a separate, secure repository for encryption keys, while the storage media retains data in encrypted form. This separation ensures that even if storage media data is recoverable, the extracted keys needed to decrypt it are not accessible without proper authentication and secure deletion upon logout.
Solution Approach 2:
The TPM acts as an intermediary between the user and the encrypted data on storage media. It mediates key management by securely storing encryption keys, controlling their release based on authentication state, and ensuring their secure deletion when no longer needed. This intermediary role resolves the contradiction by providing secure key handling independent of the storage media's deletion capabilities.
2Ease of operation
If encryption keys are stored in easily accessible form during device updates, then update operation capability is improved, but security protection deteriorates due to potential key exposure
Solution Approach 1:
The system performs preliminary actions by pre-authenticating the update operation and verifying the update package's digital signature before making encryption keys accessible. The TPM validates the update's authenticity in advance, and only after successful validation does it release the necessary keys. This preliminary verification ensures that keys are exposed only when absolutely necessary and for verified operations, resolving the contradiction between update capability and security.
3Reliability
If whole volume encryption is implemented, then data security during physical access is improved, but key management complexity increases due to multiple key layers and state-dependent decryption
Solution Approach 1:
The patent merges the key storage function with the TPM's authentication state tracking capability. Instead of separate key storage and state management systems, the TPM integrates both functions, automatically controlling key release based on the current authentication state. This merging simplifies key management by eliminating the need for separate state-dependent key management logic while maintaining strong security during physical access.
Data Source
AI summary
Temporarily sensitive information can be stored in the non-volatile storage of a TPM, from which it can be securely, and irretrievably, deleted. Additionally, information stored in a TPM can secure information stored on communicationally disconnectable storage media such that, when communicationally disconnected, the information stored on such media is inaccessible. A whole volume encryption service key can be protected by a key stored in a TPM and, even if the protector remains accessible, the secure deletion of the key from the TPM prevents unauthorized disclosure of the whole volume encryption service key. Additionally, TPM stored data can be released only when a computing device is in a particular state, as determined by the PCRs. A hibernation image can be encrypted and the key stored with the TPM such that it is released to decrypt the image and restore active computing only if the state has not materially changed during hibernation.