Segmented Secret Key Storage for Hardware Security Bottlenecks
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Solution Overview
Problem
Hardware solutions like TPM and HSM for secret key storage are slow and lack capacity to handle large numbers of keys, and periodic key updates pose a risk of secret information leakage until the update is completed.
Innovation Solution
A segmented secret-key storage system that divides a secret key into segments, each stored on a separate apparatus, where decryption or signature operations are performed, and the segments are periodically updated to ensure that the key is not revealed unless all segments are compromised.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a secret key is stored in a single hardware apparatus (TPM or HSM), then the key storage is secure, but the system speed is slow and the capacity to store large numbers of keys is insufficient
Solution Approach 1:
The secret key is divided into multiple segments (first secret-key segment, second secret-key segment, etc.) and distributed across multiple segment storage apparatuses. Each apparatus stores only a portion of the key, and the key can be reconstructed when a predetermined number of segments are combined. This segmentation enables parallel processing and distributes the storage burden, thereby improving system speed and capacity while maintaining security through the requirement of multiple segments for key reconstruction.
2Reliability
If a secret key is updated periodically or under predetermined conditions, then the risk of long-term key exposure is reduced, but secret information may leak during the update period
Solution Approach 1:
The secret key segments are dynamically updated in a distributed manner across multiple storage apparatuses. Each segment can be updated independently and at different times, allowing the system to transition from one key state to another without creating a single point of vulnerability. The key reconstruction function can operate with different combinations of segments, providing flexibility in managing key updates and reducing the risk of information leakage during transitions.
3Reliability
If a secret key is divided into multiple segments stored on separate apparatuses, then the security against key leakage is improved, but the system complexity increases
Solution Approach 1:
The key reconstruction function is designed to be universal, accepting any combination of secret-key segments that meets the predetermined threshold. This multi-functional capability allows the system to work with different numbers and combinations of segment storage apparatuses without requiring fundamentally different reconstruction mechanisms. The function can handle various segmentation schemes and update strategies, reducing the complexity burden by providing a unified approach to key management.
Data Source
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AI summary
The risk of leakage of secret information caused by leakage of the secret key is reduced. A segmented secret-key storage system according to the present invention segments a secret key SK into segments that can be combined at the time of decryption or at the time of generation of a signature and records the secret-key segments sk1, ..., skN in segment storage apparatuses. The secret-key segments are changed, periodically or under a predetermined condition, to another set of secret-key segments that satisfies a condition for combination. According to the segmented secret-key storage system of the present invention, the secret key SK is not revealed unless the secret-key segments are stolen from all the segment storage apparatuses in an interval between changes made to the secret-key segments. Accordingly, the risk of leakage can be greatly reduced in comparison with the risk of leakage of the secret key from a single apparatus.