Semiconductor Key Protection via OTP Control Logic

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Solution Overview

Problem

Semiconductor devices with fused keys in one-time programmable (OTP) memory are vulnerable to unauthorized access and key leakage before secure features are enabled, posing a security risk.

Innovation Solution

Incorporating a key protection control logic circuit and key protection setting areas in the semiconductor device, which determines whether to load the key into a key register based on programmed setting values, ensuring the key is not accessible until secure features are enabled, thereby preventing unauthorized access.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the key is permanently programmed in OTP memory during fabrication, then the key is securely stored and cannot be changed, but the key becomes vulnerable to unauthorized access and leakage before secure features are enabled

Engineering Contradiction:

Improvekey storage securityVSAvoidunauthorized key access

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A key protection control logic circuit is introduced as an intermediary between the OTP memory and the key register. This control circuit reads setting values from key protection setting areas and determines whether to load the key into the key register, thereby mediating access control to the key

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

Key protection setting areas are programmed with setting values before the key is made accessible. These pre-programmed setting values enable the control logic circuit to determine in advance whether key loading should be permitted, preventing unauthorized access before secure features are enabled

Inventive Principle:

Principle #10Preliminary action

2Ease of operation

If the key is made accessible to secure software, then secure software can function properly, but unauthorized third parties may access and leak the key

Engineering Contradiction:

Improvesecure software functionalityVSAvoidkey leakage

Core Design Contradiction:

Ease of operationVSLoss of information

Solution Approach 1:

The key protection control logic circuit serves as a mediator that controls key loading into the key register based on setting values. This ensures that only authorized secure software can access the key through the key register, while preventing unauthorized access and potential key leakage

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If key protection setting areas are added to control key access, then unauthorized key access is prevented, but device complexity increases

Engineering Contradiction:

Improvekey access controlVSAvoidmemory structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The OTP memory is segmented into distinct functional areas: a key program area for storing the key and multiple key protection setting areas for storing control values. This segmentation allows the key protection control logic circuit to read setting values and determine key loading, implementing access control with modular memory structure

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS10923203B2Semiconductor device and method of operating semiconductor device

Publication Date: 2021.02.16 SAMSUNG ELECTRONICS CO LTD

AI summary

A semiconductor device includes a one-time programmable (OTP) memory including a key program area and a plurality of key protection setting areas. A key is stored in the key program area, and a plurality of setting values that protect the key stored in the key program area are programmed in the key protection setting areas. The semiconductor device further includes a key register and a key protection control logic circuit. The key register is configured to load the key stored in the OTP memory. The key is accessible to secure software when the key is loaded into the key register. The key protection control logic circuit is configured to load the key stored in the OTP memory into the key register based on the setting values programmed in the key protection setting areas of the OTP memory.