OTP Chip Security via Internal Controller and Selector
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing chips have poor security due to exposed enable pins allowing attackers to re-activate the programming interface of one-time programmable (OTP) devices, enabling unauthorized access to sensitive information.
Innovation Solution
A chip design that includes a selector, a one-time programmable device, and a controller, where the controller detects the device value and provides selection signals to control access, preventing unauthorized access by hiding the burning enabling port and using an address filter to protect important data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an en pin is exposed on the exterior to control access to the OTP device, then the programming interface can be activated for burning, but the security of the chip deteriorates because attackers can re-activate the programming interface
Solution Approach 1:
The enable function is extracted from the external pin and moved inside the chip to the controller. The controller internally manages the enable state based on device value detection, eliminating the need for an external en pin that could be exploited by attackers.
Solution Approach 2:
The controller acts as an intermediary between the external interface and the OTP device. It detects the device value and uses the selector to control whether access data reaches the OTP device, preventing direct unauthorized access while allowing legitimate burning operations.
2Object-affected harmful factors
If the controller detects device value and controls access internally, then security is improved by hiding the burning enabling port, but the device complexity increases
Solution Approach 1:
The controller performs multiple functions: it detects the device value, determines whether burning has occurred, controls the selector to manage access, and manages the overall burning process. This multi-functionality reduces the need for separate dedicated components for each function.
Solution Approach 2:
The enable control logic is merged into the controller's existing device value detection and control functions. The selector is integrated into the access path between the external interface and the OTP device, creating a unified control mechanism rather than separate independent systems.
3Object-affected harmful factors
If the selector controls access data to the OTP device based on controller signals, then unauthorized access is prevented after burning, but the access control mechanism becomes more complex
Solution Approach 1:
The controller detects the device value in advance to determine whether burning has occurred before allowing access. The selector is pre-configured with control inputs that will automatically route access data appropriately based on the burning state, preventing unauthorized access before it can occur.
Solution Approach 2:
The selector creates a controlled copy path for access data. When burning is detected, the selector routes access data to a default state that prevents OTP device access, while allowing legitimate burning operations through the controller's management of the control signal.
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
Embodiments of the present invention provide a chip and a chip burning method. The chip includes: a selector, a one time programmable device, and a controller. The controller is separately connected to a selection end of the selector and the one time programmable device, and the controller is configured to detect a device value of the one time programmable device, and provide a first selection signal to the selection end of the selector when the device value of the one time programmable device is within a first preset range. A first input end of the selector is configured to receive access data, a second input end of the selector is configured to receive a preset invalid value, and an output end of the selector is connected to the one time programmable device. The selector is configured to: when the first selection signal is input to the selection end, control the data received by the second input end to be output from the output end of the selector. According to the chip provided in the embodiments of the present invention, there is no burning enabling port exposed on an exterior, and a feature value for controlling an access data input end cannot be modified after being burned. In this way, chip security can be improved.