OTP Control Logic Randomization for Fuse Security
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Solution Overview
Problem
One-Time Programmable (OTP) fuse boxes in silicon manufacturing are vulnerable to fault injection and side-channel leakage attacks, which allow attackers to disrupt or infer sensitive information stored in fuses without altering the fuse box contents or accessing the programming process.
Innovation Solution
Implementing OTP control logic with randomization in both timing and address order to prevent predictable sequencing, using a clock signal interrupt circuit and address transformation mechanisms to obscure the address determination process, thereby making the fuse value sensing and writing process unpredictable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If predictable OTP control logic is used, then ease of operation and manufacturing are improved, but security against fault injection and side-channel attacks deteriorates
Solution Approach 1:
The patent applies dynamics by making the OTP control logic unpredictable through randomization of the address counter sequencing. Instead of a fixed, predictable sequence, the address counter now follows a randomized path determined by random values injected into the system. This dynamic behavior prevents attackers from predicting which fuses will be accessed or in what order, thereby defending against fault injection and side-channel attacks while maintaining ease of operation.
Solution Approach 2:
The patent changes the parameter of address counter sequencing from a fixed, deterministic sequence to a randomized sequence. By introducing random values that alter the addressing pattern, the system transforms the predictable behavior into an unpredictable one. This parameter change ensures that each execution of the OTP control logic follows a different path, making it impossible for attackers to reliably predict fuse access patterns or inject faults at specific points.
2Object-affected harmful factors
If randomization is added to OTP control logic, then security is improved, but device complexity increases
Solution Approach 1:
The patent introduces an intermediary element in the form of a random value generator and injection mechanism that sits between the predictable address counter and the fuse array. This intermediary randomizes the addressing sequence without requiring fundamental changes to the underlying OTP control logic or fuse box structure. The randomization layer acts as a mediator that adds security while keeping the core system architecture relatively simple.
Solution Approach 2:
By implementing dynamic randomization in the address counter sequencing, the patent adds security functionality without permanently increasing structural complexity. The randomization is achieved through software or firmware-controlled random value injection rather than hardwiring complex logic, allowing the system to maintain simplicity while achieving unpredictable behavior. The dynamic nature of the randomization allows the same hardware to produce different execution paths without requiring additional physical components.
Data Source
AI summary
A method and apparatus are described for OTP control logic with randomization for sensing and writing fuse values. In an embodiment, OTP control logic has an address counter to determine an address of a fuse to be read from an OTP fuse box and a corresponding address of a shadow register, a fuse box addressing circuit to read a fuse value from a fuse of the fuse box, a clock circuit coupled to the address counter to provide a clock signal to the address counter, and a randomization circuit to interrupt the clock signal at random times to prevent the address counter from determining a next address in response to the clock signal.