Cryptographic Chip Rule-Based Access Control
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Solution Overview
Problem
Current cryptographic chipsets are vulnerable to reverse engineering attacks and key exposure due to direct access by General Purpose Processors (GPPs) and lack flexibility in secure key handling, especially in consumer devices like set-top boxes and smartphones.
Innovation Solution
A cryptographic chip with a secured processor module that employs a mixture of software and hardware shielding, utilizing a key storage module, a rule storage module, and an interface module to enforce rule-based access control and separation-of-concerns, preventing direct access to cryptographic keys and operations by GPPs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If General Purpose Processors directly access cryptographic keys and operations, then ease of operation is improved, but security against reverse engineering attacks deteriorates
Solution Approach 1:
The patent introduces a secured processor module as an intermediary between the GPP and cryptographic keys/operations. This module includes a key storage module, rule storage module, and cryptographic module that act as mediators, allowing GPPs to perform cryptographic operations without direct access to sensitive keys and algorithms, thereby maintaining ease of operation while improving security
Solution Approach 2:
The patent segments the processor into two distinct modules: a GPP for general-purpose operations and a secured processor module for cryptographic operations. This segmentation isolates sensitive cryptographic functions and keys from direct GPP access, reducing the attack surface for reverse engineering while maintaining system functionality
2Ease of operation
If cryptographic keys are stored in accessible memory, then ease of operation is improved, but reliability of key protection deteriorates
Solution Approach 1:
The key storage module within the secured processor module serves as an intermediary that stores cryptographic keys securely. The keys are made available to cryptographic operations through controlled interfaces rather than direct memory access, maintaining operational efficiency while ensuring reliable key protection through hardware-based security boundaries
Solution Approach 2:
The patent applies different security qualities to different parts of the system: the GPP operates with standard accessibility, while the secured processor module implements restricted access policies. Specifically, the key storage module uses hardware-enforced access controls that differ from standard memory access, providing localized high-security protection where needed
3Adaptability or versatility
If flexible key handling is implemented, then adaptability is improved, but device complexity increases
Solution Approach 1:
The secured processor module is designed as a universal interface that handles multiple cryptographic operations (encryption, decryption, key derivation) through a unified rule-based access control mechanism. The rule storage module stores access policies that can be configured for different keys and operations, providing flexible key handling without requiring separate hardware for each function, thus managing complexity while maintaining adaptability
Data Source
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Figure 3
Figure 3A~3C
AI summary
There is described a method of loading a new rule into a rule storage module of a chip. The chip further comprises a key storage module configured to store one or more cryptographic keys. The rule storage module is configured to store one or more rules, each rule comprising respective rule data. The rule data identifies a respective predetermined cryptographic operation associated with the rule and further identifying at least one of the one or more cryptographic keys to be used in the respective predetermined cryptographic operation. The method comprises: (a) receiving a rule loading request, wherein the rule loading request comprises a new rule identifier to identify the new rule to be loaded and further comprises new rule data defining the new rule, the new rule data identifying a specific cryptographic operation associated with the new rule and further identifying at least one of the one or more cryptographic keys to be used in the specific cryptographic operation; (b) assessing whether the rule loading request is allowable; and (c) in response to the rule loading request having been assessed as allowable, loading the new rule into a programmable portion of the rule storage module such that the new rule becomes one of the one or more rules.