Hardware Cryptographic Module Key Storage Expansion
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Solution Overview
Problem
Hardware security modules have limited storage capacity for cryptographic keys, making it challenging to support enhanced security features in connected vehicle systems, especially with the rise of IoT and connected services, and are costly to expand.
Innovation Solution
A method that determines if non-transitory memory in a hardware cryptographic module is available for storing private cryptographic keys; if not, it encrypts the key with a session parameter and a nesting parameter, then stores the encrypted key in a less secure memory environment, allowing for secure storage outside the secure environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cryptographic keys are stored in hardware security module memory, then security is maintained, but storage capacity is limited to approximately ten 128-bit keys
Solution Approach 1:
The cryptographic key storage is segmented into two parts: the private key material remains in the secure hardware security module, while only the encrypted public key is stored in the external less-secure memory. This segmentation allows the system to maintain security requirements while expanding storage capacity beyond the HSM's internal limitations.
Solution Approach 2:
The patent extracts the public key from the secure HSM environment and stores it externally in less-secure memory after encryption. This extraction enables the system to utilize external storage resources while the critical private key material remains protected within the HSM boundaries.
2Quantity of substance
If hardware security module memory is expanded to store more keys, then storage capacity increases, but cost increases significantly
Solution Approach 1:
The patent uses inexpensive external memory resources to store encrypted public keys, replacing the need for expensive expanded HSM memory. The encrypted data can be regenerated if needed, making the external storage effectively disposable and cost-effective compared to expanding secure hardware memory.
3Quantity of substance
If private cryptographic keys are stored in less secure memory environments, then storage capacity increases, but security risk increases
Solution Approach 1:
Different security measures are applied to different parts of the cryptographic data: the private key material maintains high-security storage within the HSM, while the public key (which is less sensitive) is stored externally with lower security measures. This local differentiation of security quality allows external storage while maintaining overall system security.
Solution Approach 2:
The system uses a composite security approach combining secure HSM storage for private keys with less-secure external storage for encrypted public keys. This composite structure leverages the strengths of both secure and insecure storage environments, achieving both security and expanded capacity.
Data Source
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AI summary
The invention relates to a method of managing private cryptographic keys, the method comprising:determining whether non-transitory memory of a hardware cryptographic module is available in response to a request to store a private cryptographic key;in the event the non-transitory memory of the hardware cryptographic module is available, storing the private cryptographic key therein;in the event the non-transitory memory of the hardware cryptographic module is insufficient:encrypting, by the hardware cryptographic module,the private cryptographic key with a session para meter comprising a short-term session key and a random number,to produce a first encrypted parameter;encrypting, by the hardware cryptographic module,the session parameter with a nesting parameter comprising a nesting key and a random number,to produce a second encrypted parameter, wherein the encrypted private cryptographic key comprises the first encrypted parameter and the second encrypted parameter;storing the encrypted private cryptographic key in a second non-transitory memory having lower security certification than the non-transitory memory of the hardware cryptographic module.The invention further relates to an electronic control unit that when in use can perform the method.