CAN Bus Authentication With Dynamic Shared Keys at Vehicle Ignition
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Solution Overview
Problem
Existing CAN bus communications in vehicles lack security measures for authentication and integrity, as they rely on static shared secret keys that can be easily compromised, leading to potential attacks and manipulation of critical vehicle functions.
Innovation Solution
Dynamically derive a shared secret key upon vehicle ignition, using one-time passcodes based on timestamp, geographical location, and a master key, eliminating the need for pre-provisioned static keys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If static shared secret keys are pre-provisioned to ECUs for CAN bus communication, then authentication and integrity protection can be provided, but the security risk increases because the keys can be easily compromised and a single compromise enables attacks on all associated ECUs
Solution Approach 1:
The patent transforms the static shared secret key into a dynamic key that changes over time. The system derives a shared secret key dynamically based on the current time and a pre-shared seed, so the key is different at each moment. This resolves the contradiction by maintaining authentication reliability while eliminating the risk of static key compromise, as each key instance is unique and time-limited
Solution Approach 2:
The patent changes the parameter of the secret key from static to time-dependent. By incorporating time as a variable in key derivation (using current time and a pre-shared seed to generate a time-varying shared secret), the system maintains authentication capability while making key compromise significantly more difficult, as a compromised key at one time point cannot be used at other time points
2Object-affected harmful factors
If hardware security modules (HSM) are introduced to secure static shared secret keys, then key security is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the need for HSM by removing the requirement to store static secret keys in hardware security modules. Instead, the system uses software-based dynamic key derivation from a simple pre-shared seed and current time, eliminating the need for complex HSM infrastructure while maintaining or improving security
Solution Approach 2:
The patent employs ephemeral, software-based keys that are generated and discarded continuously based on time, replacing expensive, permanent hardware security modules. The keys have short lifetimes and are derived computationally rather than stored physically, significantly reducing hardware complexity and cost while maintaining security
3Ease of manufacture
If pre-provisioned static keys are used across ECUs, then ease of provisioning is improved, but security vulnerability increases because compromising one key compromises all ECUs using that key
Solution Approach 1:
The patent maintains provisioning simplicity by using a single pre-shared seed across all ECUs, but transforms the security model by making the actual operational keys dynamic and time-dependent. This resolves the contradiction because while provisioning remains easy (same seed for all), security resilience improves dramatically since each ECU generates unique time-varying keys, so compromising one ECU's key does not compromise others
Data Source
AI summary
Example embodiments of the present disclosure provide secured controller area network (CAN) communications among vehicle components. According to embodiments, a method for providing may include: generating, by at least one processing unit of a sender, a one-time passcode (OTP); obtaining, by the at least one processing unit of the sender, a master key pre-provisioned to the sender and the receiver; deriving, by the at least one processing unit of the sender, a shared key based on the OTP and the master key; generating, by the at least one processing unit of the sender, a message authentication code (MAC) based on the derived shared key; appending, by the at least one processing unit of the sender, the MAC to a message; and transmitting, by the at least one processing unit of the sender, the appended message to a receiver via a CAN bus.