ECU Update Authentication Using Dynamic Entropy Random Numbers
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Solution Overview
Problem
Existing software update systems for electronic control units (ECUs) in vehicles lack sufficient security measures to prevent unauthorized updates, making them vulnerable to illegal software modifications.
Innovation Solution
An information processing apparatus with a random number generation unit that updates entropy based on multiple clock signals with different frequencies, performing logical operations to increase randomness, which is then used for authenticating the update control device, enhancing security during software updates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a random number is generated from fixed entropy for authentication, then the authentication process is simple, but the security is insufficient because the random number can be predicted
Solution Approach 1:
The patent applies the dynamics principle by making the entropy value changeable rather than fixed. The entropy is updated periodically by incorporating new random data from the clock signal, transforming the static entropy into a dynamic value that evolves over time. This ensures that each authentication process uses fresh entropy, preventing prediction attacks while maintaining a manageable generation process through periodic updates rather than continuous complex operations.
Solution Approach 2:
The patent implements parameter changes by modifying the entropy value itself as a key parameter. The entropy is transformed from a fixed initial value to a changing value that incorporates new random data from the clock signal at regular intervals. This parameter change ensures that the random number generation remains unpredictable and secure, as the entropy parameter continuously evolves rather than remaining static.
2Reliability
If entropy is updated frequently with new random data, then the randomness and security are improved, but the processing time and energy consumption increase
Solution Approach 1:
The patent applies periodic action by updating the entropy value at fixed time intervals rather than continuously or on every authentication request. The update process is triggered periodically based on time elapse, which balances the need for fresh random data with the constraint of processing time. This periodic update mechanism ensures sufficient randomness quality while avoiding excessive processing overhead that would occur with more frequent updates.
3Productivity
If the entropy buffer is fully utilized for random number generation, then the efficiency is high, but the predictability risk increases if any part of the entropy is compromised
Solution Approach 1:
The patent implements local quality by dividing the entropy buffer into multiple regions with different characteristics. The buffer includes a first region for storing the current entropy value and a second region for storing updated entropy values. This spatial division allows the system to utilize the entire buffer for random number generation (maintaining efficiency) while isolating compromised portions (maintaining security). If one region is compromised, the other regions remain secure and can continue to provide unpredictable random data.
Data Source
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AI summary
An authentication unit of an information processing apparatus authenticates an update control device that controls update of a control program by using a random number generated by a random number generation unit. In the random number generation unit, a first extraction unit extracts a bit value from a count value of a first clock signal, a calculation unit performs logical operation on the bit value extracted by the first extraction unit and a target bit value at a bit position included in an entropy as an update position that is designated, a replacement unit replaces the bit value at the update position with a result of the logical operation a position designation unit designates a new update position after the bit value is replaced, and an output unit generates the random number from the entropy.