Vehicle Controller Entropy Sampling for Replay-Resistant Random Numbers
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Solution Overview
Problem
Conventional vehicle ECUs lack sufficient randomness in generating challenge responses, making them vulnerable to replay attacks and unauthorized access through protocols like UDS SecurityAccess and Authentication services.
Innovation Solution
Generate pseudo-random numbers using alternative sources such as response time, power-based, and random walk-based methods, which do not require additional hardware, by sampling energy values or transmission times to create an entropy pool and using cryptographic algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ECUs use standard random number generation methods, then the system is simple and does not require additional hardware, but the randomness is insufficient making the system vulnerable to replay attacks
Solution Approach 1:
The ECU uses its own existing operational characteristics (response times, power consumption patterns, internal state transitions) as entropy sources for random number generation, eliminating the need for external hardware while improving security
Solution Approach 2:
The system transforms measurable operational parameters (response time variations, power consumption values, state transition timings) into cryptographic entropy through processing by a random number generator, converting ordinary operational data into secure random numbers
2Reliability
If additional hardware is added to generate true random numbers, then the randomness and security are improved, but the device complexity and cost increase
Solution Approach 1:
The ECU leverages its own operational characteristics as entropy sources, making the existing system serve the dual purpose of normal operation and secure random number generation without requiring additional dedicated hardware components
Solution Approach 2:
The ECU's operational parameters serve multiple functions: normal control operations and entropy source for cryptographic random number generation, maximizing resource utilization without adding dedicated hardware
Data Source
AI summary
A system and method is disclosed for generating a random number to prevent unauthorized access to an application-layer communication protocol within a vehicle. A plurality of instantaneous energy values for an energy source within the vehicle may be sampled until the first controller determines the plurality of instantaneous energy values have exceeded a predetermined value indicating an entropy pool has been created. One more of the plurality of instantaneous energy values within the entropy pool may then be selected as an input seed to a cryptographic algorithm operable to generate the pseudo-random number.