Payment Key Protection with AES, SM4 White Box, and SM2

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Solution Overview

Problem

Existing payment key security mechanisms face challenges in balancing encryption speed and management complexity, particularly in electronic payment systems, where symmetric and asymmetric keys are used together, necessitating improved protection against unauthorized exposure.

Innovation Solution

A method involving the generation of AES file and AES keys through a key store management system, combined with SM4 white box secret and SM2 public keys, for triple encryption of payment keys, along with a decryption process requiring access to the SM2 private key and subsequent decryption by AES and SM4 white box secret keys, ensuring secure protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If symmetric key is used for data encryption, then encryption speed is improved, but key management difficulty increases

Engineering Contradiction:

Improveencryption speedVSAvoidkey management difficulty

Core Design Contradiction:

SpeedVSEase of operation

Solution Approach 1:

The patent divides the key management system into multiple components: symmetric keys for data encryption, asymmetric key pairs for key exchange, and hybrid encryption schemes. This segmentation allows each key type to be used for its optimal purpose while reducing overall management complexity through structured organization.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If asymmetric key is used for data encryption, then key management flexibility is improved, but encryption speed decreases

Engineering Contradiction:

Improvekey management flexibilityVSAvoidencryption speed

Core Design Contradiction:

Adaptability or versatilityVSSpeed

Solution Approach 1:

The patent merges symmetric and asymmetric encryption mechanisms into a hybrid system. Asymmetric keys are used for secure key exchange and digital signatures, while symmetric keys handle bulk data encryption. This combination leverages the flexibility of asymmetric encryption for key management and the speed of symmetric encryption for data processing.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If payment key is protected using conventional encryption, then security is improved, but complexity of encryption system increases

Engineering Contradiction:

Improvepayment key securityVSAvoidencryption system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces intermediate key layers and hybrid encryption schemes as mediators between the payment key and external systems. Instead of directly encrypting the payment key with a single complex mechanism, the system uses multiple intermediate encryption layers (symmetric and asymmetric keys) that simplify the overall structure while enhancing security through defense in depth.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS12367488B2Encryption method and decryption method for payment key, payment authentication method, and terminal device

Publication Date: 2025.07.22 SHENZHEN PAX SMART NEW TECH CO LTD

AI summary

An encryption method and a decryption method for a payment key are provided. The encryption method includes: generating an AES file key and an AES key through a key store management system; generating, by the back-end system, a SM4 white box secret key, a SM2 public key and a SM2 private key and saving the SM2 private key; receiving the SM4 white box secret key and the SM2 public key sent by the back-end system; encrypting, by using the AES file key, the SM4 white box secret key and the SM2 public key to generate and save a ciphertext of the SM4 white box secret key and the SM2 public key; encrypting, using the SM4 white box secret key, the AES key and the SM2 public key, a plaintext of the payment key issued by an electronic payment system to generate and save a ciphertext of the payment key.