Transponder Authentication via Transmission Delay and Counter

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Solution Overview

Problem

Current authentication methods for transponders in communication with servers are vulnerable to relay attacks and cannot guarantee the authenticity of products or objects, as they rely on one-time passwords that can be intercepted and reused by malicious devices, lacking secure two-way communication and robust countermeasures.

Innovation Solution

A secure authentication method that generates a unique password for each reading event, using a combination of a counter state and transmission delay encrypted with a secret key, transmitted to a server via a reading device, which verifies the authenticity by comparing the decrypted delay and counter state, ensuring the transponder is genuine and preventing replay attacks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a challenge-response protocol with encryption is used to authenticate the transponder, then the authentication security is improved, but the device complexity increases due to the need for special applications and intermediate reading devices

Engineering Contradiction:
Improveauthentication securityVSAvoidcommunication protocol complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the authentication logic from the mobile phone and places it in the transponder itself. The transponder autonomously generates the unique password using its internal counter and secret key, eliminating the need for complex challenge-response protocols on the mobile device. This simplifies the user-side application while maintaining security.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The transponder performs self-authentication by generating its own unique password based on its internal counter state and secret key. The transponder serves itself by creating the authentication credential without requiring complex external authentication mechanisms, thereby simplifying the overall system architecture.

Inventive Principle:
Principle #25Self-service

2Ease of operation

If a one-time password is generated and transmitted to the server, then the authentication process is simplified, but the system becomes vulnerable to relay attacks and replay attacks

Engineering Contradiction:
Improveauthentication process simplicityVSAvoidvulnerability to relay and replay attacks
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The transponder includes a counter that is incremented with each reading event before generating the unique password. This preliminary action of updating the counter ensures that each password is tied to a specific reading event sequence, preventing replay attacks where intercepted passwords could be reused later.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The server receives the unique password and the counter state from the transponder, verifies the counter state to ensure it matches expected sequence, and then authenticates the transponder. This feedback mechanism allows the server to detect and prevent relay attacks by verifying the temporal and sequential validity of each authentication attempt.

Inventive Principle:
Principle #23Feedback

3Reliability

If the transponder uses a counter state and transmission delay in the unique password, then the security against replay attacks is improved, but the manufacturing precision requirements increase

Engineering Contradiction:
Improvesecurity against replay attacksVSAvoidtransmission delay control precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent uses the transmission delay as a variable parameter in the unique password generation. Instead of requiring precise control of transmission timing, the system incorporates the actual measured transmission delay into the password itself. This parameter change approach allows the system to adapt to varying transmission conditions while maintaining security, as each password reflects the specific timing characteristics of its generation.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3671498B1Method for secure authentication of a transponder communicating with a server
Publication Date: 2023.08.09 EM MICROELECTRONIC-MARIN
  • EP3671498B1 patent drawingFigure 1~2

AI summary

The invention relates to a method of authenticating a transponder (1) in communication with a server (2).The method includes the steps of: - calculating a unique password (OTP) in the transponder using a dedicated algorithm based on the state of a counter and a physical quantity, such as a transmission delay determined in the transponder during a reading by a reading device (3), - transmitting the unique password to the server by the reading device, which determines a transmission delay of the transponder, and transmitting to the server in addition to the unique password, the information of the transmission delay determined in the reading device, - decrypting by the dedicated algorithm the received unique password, and - checking if the decrypted transmission delay of the received unique password corresponds to the transmission delay determined by the reading device within a determined time margin, and if the state of the counter is different from a previous counter state received to authenticate the transponder.