Embedded Chip Initialization with Batch Key Derivation
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Solution Overview
Problem
Existing chip initialization methods are inefficient and time-consuming in personalization stations due to the need for individual cryptographic operations for each chip, particularly in replacing issuer-unspecific keys with issuer-specific keys, leading to high processing times and limited throughput.
Innovation Solution
A method involving loading an image with a non-specific master key onto multiple chips, followed by deriving unique keys within the chips using batch-specific data, allowing issuer-specific keys to be transitioned en masse outside the chip, reducing the need for individual chip-specific calculations in personalization stations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If individual key derivation is performed for each chip in the personalization station, then security is maintained, but personalization time and processing cost increase significantly
Solution Approach 1:
The patent performs preliminary key derivation by generating a master key in the HSM and encrypting it with the chip's public key during chip manufacturing. This pre-computed encrypted master key is stored in the chip, eliminating the need for time-consuming individual key derivation during personalization. The cryptographic operations are moved to the manufacturing phase rather than the personalization phase.
Solution Approach 2:
The patent creates a copy of the master key encrypted with each chip's unique public key. Instead of performing cryptographic operations on each chip individually during personalization, the system pre-creates encrypted key copies during manufacturing that can be efficiently loaded during personalization without requiring HSM involvement for each chip.
2Reliability
If individual cryptographic operations are performed for each chip, then key uniqueness is guaranteed, but processing throughput decreases
Solution Approach 1:
The patent performs the computationally intensive cryptographic operations during chip manufacturing when chips are processed in batches. The master key is derived once in the HSM and then encrypted with multiple chip public keys in advance, allowing high-volume personalization later without repeated cryptographic operations for each chip.
Solution Approach 2:
The patent merges multiple individual key derivation operations into a single master key generation operation followed by batch encryption. Instead of performing separate cryptographic operations for each chip, the system combines the process by deriving one master key and then efficiently encrypting it for multiple chips, thereby increasing throughput while maintaining uniqueness.
3Reliability
If master key derivation is performed for each issuer and each chip, then security is maximized, but cost and complexity increase
Solution Approach 1:
The patent segments the key management process into distinct phases: master key derivation for each issuer is performed once during HSM initialization, while individual chip key encryption is performed during manufacturing. This segmentation eliminates the need for complex per-chip master key derivation during personalization, reducing both cost and complexity while maintaining security.
Solution Approach 2:
The patent performs preliminary master key derivation for each issuer during HSM setup before any chip personalization occurs. This pre-computed issuer-specific master key is then reused for encrypting multiple chips, eliminating the need to repeat the derivation process for each chip and thereby reducing personalization complexity and cost.
Data Source
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AI summary
The invention provides a method for chip initialization of an embedded system chip by loading an image containing at least one operating system and key information that is identical for a plurality of chips, comprising the steps: (1) loading the image into the chip; (2) loading into the chip, (2.1), (2.2) either a master key KMC(M) encrypted with an initial encryption key (SMK(M)), which is stored, in particular encrypted, outside the embedded system chip, and optionally batch-specific key derivation data (DDBatch), wherein the image contains the initial encryption key (SMK(M)) as key information; (2.3), (2.4) or from key derivation data (DDKMC) or batch-specific key derivation data (DDBatch) to derive an issuer- or batch-specific master key (KMC(M)) from the personalization master key (ISK(M)), wherein the image contains the initial personalization master key (ISK(M)) as key information; (3) In the embedded system chip, deriving a key (KMC(D)) unique to each embedded system chip, either (3.1), (3.2) from the issuer-specific master key KMC(M), and optionally batch-specific key derivation data (DDBatch), or (3.3), (3.4) from the initial personalization key (ISK(M)) and the specific key derivation data (DDKMC) or batch-specific key derivation data (DDBatch).