Electronic Key Authentication Using Location-Verified Sequential OTPs
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Solution Overview
Problem
Electronic key systems are vulnerable to relay attacks, where malicious third parties intercept and amplify legitimate data to unlock doors or ignition systems, bypassing encryption and authentication, leading to potential theft.
Innovation Solution
An electronic key system that generates and verifies one-time passwords (OTPs) from both internal and external locations, requiring multiple valid OTPs to unlock doors and activate devices, using internal/external determination modules to authenticate and authorize access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If predetermined data is transmitted wirelessly from the key device to the information processing device, then the electronic key system provides convenient access without physical key insertion, but the system becomes vulnerable to relay attacks where malicious third parties can intercept and amplify the data to unlock doors remotely
Solution Approach 1:
The system performs preliminary actions by transmitting multiple pieces of predetermined data sequentially before the unlocking operation. The information processing device receives and validates each piece of data in order, ensuring that the key device is in proper proximity and has not been relayed through intermediate devices. This preliminary validation sequence prevents relay attacks by establishing temporal and spatial authenticity before granting access.
Solution Approach 2:
The system implements feedback mechanisms where the information processing device sends acknowledgment signals back to the key device after receiving each piece of predetermined data. This bidirectional communication allows the system to verify that the data transmission is occurring directly between the legitimate key device and the target device, providing real-time validation that prevents unauthorized relay attacks while maintaining convenient wireless operation.
2Reliability
If encryption processing is applied to the transmitted data, then the data security is improved, but relay attacks can still succeed because the encrypted data can be captured, amplified, and retransmitted without decryption
Solution Approach 1:
The system segments the authentication process into multiple independent steps, each requiring a separate piece of predetermined data. Instead of transmitting a single encrypted authentication token, the system divides the authentication into a sequence of data transmissions that must occur in specific order. This segmentation prevents relay attacks because capturing and retransmitting encrypted data alone is insufficient - the attacker would need to intercept and replay the entire sequential authentication sequence, which the system validates through timing and ordering checks.
Solution Approach 2:
The system employs periodic action by transmitting multiple pieces of predetermined data at different time intervals rather than a single continuous authentication signal. Each piece of data is transmitted periodically and must be received in the correct sequence. This temporal distribution makes relay attacks ineffective because the system can detect anomalies in the timing and sequence of received data, identifying relayed transmissions as fraudulent while maintaining secure encrypted communication.
Data Source
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AI summary
To provide an electronic key system which is highly resistant to relay attacks, the electronic key system is built from a combination of an automobile and a key device. A user in an external space of the automobile presses a switch on the key device to transmit an OTP 1 generated by the key device to the automobile from the key device (Step S2001 to Step S2003). When the received OTP 1 matches the OTP 1 generated by the automobile, and the received OTP 1 is determined as having been transmitted from the external space of the automobile, the automobile generates lock data and unlocks the lock (Step S1001 to Step S1005). The user enters an internal space of the automobile, and presses the switch on the key device to transmit an OTP 2 generated by the key device to the automobile from the key device (Step S2004 to Step S2006). When the received OTP 2 matches the OTP 2 generated by the automobile, and the received OTP 2 is determined as having been transmitted from the internal space of the automobile, the automobile generates ignition data and switches an ignition switch to an ON state (Step S1006 to Step S1010).