Contactless Card Identifier Obfuscation to Prevent Transaction Tracking

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Solution Overview

Problem

Conventional contactless smart card transactions expose sensitive data, such as account identifiers, to interception and tracking, as they are often unencrypted or encrypted using known protocols, making them vulnerable to fraud, and lack restrictions on usage contexts.

Innovation Solution

Implement a system where a contactless smart card uses a secondary account number (SAN) for certain transactions and an obfuscated or encrypted primary account number (PAN) for others, ensuring the SAN is restricted to specific contexts and the PAN is protected with dynamic encryption, maintaining compatibility with existing payment infrastructure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the entire account identifier is transmitted unencrypted, then the transaction processing is simple and fast, but the security is compromised and the account identifier can be intercepted and tracked

Engineering Contradiction:

ImprovesecurityVSAvoidencryption complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The account identifier is segmented into two parts: a static primary account number (PAN) stored securely in the account device, and a dynamic secondary account number (SAN) transmitted during transactions. This segmentation allows the static PAN to remain protected while the dynamic SAN enables secure transaction processing without exposing the full account identifier

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system changes the parameter of the account identifier from static to dynamic by introducing the SAN. The SAN is generated based on the PAN and a transaction counter, ensuring that the transmitted identifier changes with each transaction while maintaining a consistent format compatible with existing payment infrastructure

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the account identifier is encrypted using conventional techniques, then the security is improved, but the encrypted data field can still be easily identified by fraudsters using known protocols

Engineering Contradiction:

ImprovesecurityVSAvoiddata field identification

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The sensitive PAN is extracted from the transmitted message and replaced with the SAN. The PAN remains securely stored in the account device and is never transmitted over the communication channel. Only the SAN, which is less sensitive and dynamically changing, is included in the transaction message

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The SAN acts as an intermediary between the PAN and the communication channel. It provides the necessary account identification functionality for transaction processing while shielding the PAN from exposure during transmission, thus preventing fraudsters from identifying and intercepting the sensitive data field

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If a static identifier is used for transactions, then the transaction processing is efficient, but the account identifier can be tracked across multiple transactions

Engineering Contradiction:

Improvetransaction efficiencyVSAvoidprivacy information

Core Design Contradiction:

ProductivityVSLoss of information

Solution Approach 1:

The system transitions from a static account identifier to a dynamic SAN that changes with each transaction. The SAN is generated using the PAN and a transaction counter, ensuring that while the format remains consistent for efficient processing, the actual value changes dynamically to prevent tracking across transactions

Inventive Principle:

Principle #15Dynamics

4Reliability

If conventional encryption techniques are used, then the security is improved, but the system does not restrict usage of sensitive information across various contexts

Engineering Contradiction:

ImprovesecurityVSAvoidusage restriction

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system segments the account identification functionality into the PAN (for secure storage and context-specific usage) and the SAN (for general transaction processing). This segmentation enables different usage contexts: the SAN can be used for most transactions while the PAN remains protected and can be used only when specifically required and authorized

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different parts of the system have different security qualities: the SAN provides standard protection for general transactions, while the PAN receives enhanced protection through secure storage and restricted usage. This local differentiation of security quality allows the system to adapt to various transaction contexts with appropriate security levels

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS12531839B2Techniques for securely communicating sensitive data for disparate data messages

Publication Date: 2026.01.20 VISA INTERNATIONAL SERVICE ASSOCIATION

AI summary

Systems and methods are disclosed for securely communicating sensitive such as an identifier. A user device may receive a first message comprising a terminal type indicator. For certain values of the terminal type indicator, the user device may be configured to transmit a request message comprising a first identifier and an encrypted identifier. For other values of the terminal type indicator, the user device may be configured to generating an obfuscated identifier based at least in part on a first portion of a second identifier and a second portion of the encrypted identifier. The user device may then transmit a request message that includes the obfuscated identifier and the encrypted identifier.