CAN Bus Timing Jitter for Cryptographic Key Exchange Security
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Solution Overview
Problem
The Controller Area Network (CAN) bus systems are vulnerable to timing side-channel attacks, where adversaries can determine which node is transmitting data by measuring precise signal timing differences, compromising the security of cryptographic key exchanges.
Innovation Solution
Introducing randomized jitter into the timing of data bit transmissions to obfuscate signal transition times, making it difficult for adversaries to distinguish between nodes, and using cooperative schemes with multiple transmitters and variable impedance circuits to further obscure signal characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nodes transmit data bits simultaneously on CAN bus to enable secure key exchange, then cryptographic security is improved, but timing side-channel attacks become possible allowing adversaries to distinguish transmitting nodes
Solution Approach 1:
The patent changes the timing parameter of data transmission by introducing random jitter delays before each data bit transmission. This parameter change makes the transmission timing unpredictable and prevents adversaries from using precise timing measurements to distinguish which node is transmitting, thereby mitigating timing side-channel attacks while maintaining secure simultaneous transmission
Solution Approach 2:
The patent applies preliminary action by introducing random jitter delays before the actual data transmission occurs. This preliminary timing randomization is applied to each node's transmission schedule in advance, ensuring that even though nodes transmit simultaneously, the precise timing information that could reveal node identity is obscured before the data exchange begins
2Measurement precision
If precise timing measurements are used to identify transmitting nodes, then node identification capability is improved, but security of cryptographic key exchange deteriorates
Solution Approach 1:
The patent converts the harmful effect of precise timing measurements into a benefit by having all nodes introduce random jitter delays. This makes timing measurements imprecise from the adversary's perspective, but the jitter is coordinated among legitimate nodes so that simultaneous transmission and key exchange security are maintained. The imprecision that would normally harm identification capability is transformed into a protective feature against timing attacks
3Object-affected harmful factors
If random jitter is introduced to obfuscate transmission timing, then resistance to timing attacks is improved, but transmission synchronization may deteriorate
Solution Approach 1:
The patent applies dynamics by making the transmission timing flexible rather than fixed. Each node dynamically adjusts its transmission timing based on randomly generated jitter values, allowing the system to adapt between maintaining security through timing randomization and preserving synchronization through coordinated jitter application among legitimate nodes
Data Source
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AI summary
A method of operating at least one node in a communication network that uses a shared communication medium has been developed to reduce or eliminate timing side-channel attacks performed by an adversary that is connected to the shared communication medium. The method includes generating, with a controller in a first node, a first jitter time offset randomly generated from within a predetermined time range, and transmitting, with a transceiver in the first node, a first data bit through an output of the transceiver that is connected to a shared communication medium, the first data bit being transmitted at a first time corresponding to the first jitter time offset added to a first predetermined transmission time.