One-Time Programmable Memory Emulation with Selective Erase Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The size of one-time programmable (OTP) memories is insufficient for implementing security mechanisms and other functionalities in electronic devices, depending on device parameters and end-use types.
Innovation Solution
A method and circuit that emulate OTP memory by programming a first enable bit in a non-volatile memory with a protection value based on the state of a configuration bit and/or additional bits, restricting erasing operations based on these bits, and controlling device states through status bits in non-volatile and OTP memories.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a one-time programmable memory is used to implement security mechanisms, then security functionality is improved, but the memory size becomes insufficient for user needs
Solution Approach 1:
The patent combines OTP memory and non-volatile memory into a unified memory system where both memory types work together to provide both security functionality and extended storage capacity. The controller manages operations across both memory types, allowing the system to leverage the security properties of OTP memory while utilizing the larger capacity of non-volatile memory for additional user needs.
2Quantity of substance
If the size of OTP memory is increased to meet user needs, then memory capacity is improved, but device complexity and cost increase
Solution Approach 1:
The non-volatile memory serves multiple functions: it provides additional storage capacity beyond OTP memory, can be selectively protected with OTP-like security features when needed, and offers cost-effective capacity expansion. This multi-functional approach allows the system to achieve increased memory capacity without proportionally increasing device complexity, as the same non-volatile memory hardware serves both as bulk storage and as secure storage under certain conditions.
3Reliability
If selective erasing is forbidden in non-volatile memory to ensure security, then security is improved, but flexibility and adaptability of the device decrease
Solution Approach 1:
The system dynamically adjusts erasing permissions for non-volatile memory areas based on the state of enable bits. Some areas of non-volatile memory can have their erasing forbidden (protected) while other areas remain erasable. This dynamic control allows the device to maintain security for critical data while preserving flexibility for non-critical operations, enabling adaptability without compromising core security requirements.
Solution Approach 2:
The non-volatile memory is divided into multiple areas with different protection levels. Each area can be independently controlled with its own enable bit, allowing selective protection. This segmentation enables the system to apply security measures only where necessary while maintaining flexibility in other areas, thus resolving the contradiction between security and adaptability.
Data Source
AI summary
A state of an electronic device is controlled between an initial state, a testing state and a configured state. Transitions between the initial state and the testing state are controlled by setting or resetting a first status bit in a non-volatile memory. Transitions from the initial state or from the testing state to the configured state are controlled by setting a second status bit in a one-time programmable memory. A configuration bit of the electronic device is programmed during the initial state. A first enable bit, associated with an area of a non-volatile memory of the electronic device, is programmed to a protection value as a function of a value of the configuration bit. Programming of the first enable bit is restricted to the initial state. Erasing of the first area of the non-volatile memory is restricted based on a value of the first enable bit.