Two-Way NFC Proximity Verification Using Accelerometer Data
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Solution Overview
Problem
Short-range communication systems like NFC and RFID are vulnerable to relay attacks, where messages are relayed through an alternate channel, and existing proximity checks are either non-compliant or one-way, lacking assurance that both devices are in proximity.
Innovation Solution
Implementing a two-way proximity check using additional sensors such as light, sound sensors, and MEMS accelerometers, where both devices record and verify accelerometer data histories through cryptographic hash functions or message authentication codes to ensure mutual proximity assurance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a one-way proximity check is implemented, then the reader can verify the card's proximity, but the card cannot independently verify the reader's proximity, creating a security vulnerability to relay attacks
Solution Approach 1:
The patent implements two-way proximity verification where both the reader and card independently verify each other's proximity using accelerometer data. This inverts the traditional one-way approach by giving the card equal verification capabilities, preventing relay attacks where only the reader verifies proximity.
Solution Approach 2:
The patent uses accelerometer data as an intermediary physical measurement to establish proximity assurance. Both devices record accelerometer histories during the interaction and use these recordings to independently verify that the other device was physically present at the time of communication, creating a mutual proximity guarantee without requiring complex cryptographic protocols.
2Reliability
If existing proximity checks are implemented, then proximity verification is possible, but they violate ISO 14443 compliance by using modified frame structures
Solution Approach 1:
The patent merges proximity verification functionality with the existing ISO 14443 communication protocol by incorporating accelerometer measurements into the standard NFC interaction flow. The proximity check is combined with the normal authentication sequence, allowing both ISO compliance and proximity verification to coexist without requiring protocol modifications.
Solution Approach 2:
The system uses the devices' own built-in accelerometers to perform proximity verification, eliminating the need for external sensing infrastructure or protocol extensions. Each device independently captures and verifies accelerometer data from the other, providing proximity assurance through self-contained measurements that work within existing ISO standards.
3Reliability
If additional sensors are added to both devices, then two-way proximity assurance is achieved, but device complexity and cost increase
Solution Approach 1:
The patent uses accelerometers that serve multiple functions: they detect proximity through physical contact, verify mutual presence through correlated motion patterns, and can potentially detect user intent through movement analysis. This multi-functionality reduces the need for separate dedicated proximity sensors, minimizing added complexity while achieving robust two-way proximity assurance.
Solution Approach 2:
The patent replaces complex optical or RF-based proximity sensing systems with simple mechanical accelerometer measurements. By using the devices' existing motion-sensing capabilities to detect physical interaction patterns, the system achieves accurate proximity verification without requiring additional specialized sensors or complex processing infrastructure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides reliable, ISO-compliant two-way proximity verification, preventing relay attacks by ensuring both devices are physically close, enhancing security in NFC and RFID communications.
Implementation Method 1
both devices involved in the communication are equipped with accelerometers
Implementation Method 2
Each device executes the steps shown in Fig. 2b to obtain proximity assurance. Both devices involved in the communication each establish that the other device is in the proximity... Each device records and verify accelerometer data histories through cryptographic hash functions
Data Source
Figure 1
Figure 2a
Figure 2b
AI summary
A proximity check ensures that a card is physically close to the reader device in order to inhibit relay attacks. The proximity check makes relay attacks more difficult because an additional channel must be intercepted and/or spoofed or relayed. This solution can be used for any kind of short-range communication, including Near Field Communications (NFC).