Multi-Level Access Control via Iterative Hashing in Semiconductor Devices
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Solution Overview
Problem
Semiconductor devices require secure access control to restrict access to sensitive data and program codes stored in memory, especially through interfaces like JTAG, as devices become smaller and more complex, necessitating a method to limit access based on user permissions.
Innovation Solution
A method involving a hash operator that repeatedly performs hash operations on inputted passwords until a match is found with a stored hash value, setting access levels based on the number of iterations, with the secure controller controlling the hash operation to set access levels from highest to lower levels depending on the coincidence of hash values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If access control is implemented through repeated hash operations, then security is improved, but access time increases
Solution Approach 1:
The patent pre-calculates and stores hash values for multiple access levels before actual access occurs. When a user provides a password, the system compares it against pre-stored hash values rather than performing repeated hash operations in real-time, thus maintaining security while reducing access time.
Solution Approach 2:
The patent implements a dynamic access control mechanism where the number of hash operation repetitions is adjusted based on the required access level. Different memory regions can have different security requirements, allowing the system to perform fewer repetitions for less sensitive data and more repetitions for highly sensitive data, optimizing the balance between security and access speed.
2Adaptability or versatility
If multiple access levels are implemented with different hash repetition counts, then access control flexibility is improved, but device complexity increases
Solution Approach 1:
The patent divides the memory into multiple regions with different security levels, each region having its own access control parameters. This segmentation allows different parts of the memory to have different security requirements, providing flexibility without requiring complete redesign of the entire memory system.
Solution Approach 2:
The patent implements a universal access control mechanism that can handle multiple access levels using the same basic hash operation framework. By reusing the same hash operator and control logic for different security levels, the system achieves multi-functionality without proportionally increasing complexity.
Data Source
AI summary
An access control method of a semiconductor device includes providing an inputted password as an input of a hash operator; performing a hash operation in the hash operator and outputting a first hash value; controlling the hash operator so that the hash operation is repeatedly performed in the hash operator by providing the first hash value as an input of the hash operator when the first hash value and a second hash value stored in a nonvolatile memory do not coincide; and setting an access level with respect to the inner circuit according to the repetition number of times of the hash operation of the hash operator when the first and second hash values coincide.