White-Box Message Encryption with Seed-Based Masking Against CPA

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Solution Overview

Problem

White-box encryption algorithms are vulnerable to chosen-plaintext attacks (CPA) in real-world applications, leading to potential breaches in data security due to identical ciphertexts being generated for identical blocks, especially in environments where the encryption process is visible and modifiable.

Innovation Solution

Implement a mask generation function (MGF) within the white-box encryption algorithm to generate unique masks for each block, using a seed-based approach that integrates with existing encryption APIs, ensuring different ciphertexts are generated for different blocks, even when the same plaintext is encrypted, thereby enhancing semantic security.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If white-box encryption algorithm is used, then encryption process is visible and modifiable, but vulnerability to chosen-plaintext attacks increases

Engineering Contradiction:

Improveencryption process visibilityVSAvoidsecurity against CPA

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent introduces a mask generation function (MGF) as an intermediary component between the plaintext and the encryption process. The MGF takes the plaintext and generates a mask, which is then used to encrypt the plaintext. This intermediary mask layer prevents direct observation of the encryption process while maintaining visibility of the overall encryption flow, thereby resolving the contradiction between ease of operation and security against CPA.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments the encryption process into distinct functional components: mask generation, masking, and encryption. By dividing the encryption process into separate stages with specific functions (MGF for mask generation, separate masking step, and final encryption), the system maintains operational clarity while preventing vulnerable patterns in the encryption output, thus addressing the CPA vulnerability issue.

Inventive Principle:

Principle #1Segmentation

2Device complexity

If identical plaintext blocks are encrypted, then encryption process is simple, but ciphertexts become identical creating security vulnerability

Engineering Contradiction:

Improveencryption process simplicityVSAvoidsemantic security

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent applies preliminary action by generating a mask before the actual encryption process. The mask is generated in advance using the mask generation function, and then this pre-computed mask is used to encrypt the plaintext. This preliminary mask generation ensures that even identical plaintext blocks receive different treatment through the mask, maintaining semantic security without complicating the overall encryption process.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the encryption parameter by introducing a mask that is generated based on the plaintext content. Instead of using a fixed or simple encryption key, the system dynamically generates a mask parameter through the MGF, which then modifies the encryption process. This parameter change ensures that identical plaintext blocks produce different ciphertexts while keeping the encryption mechanism relatively simple.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If mask generation function is added, then CPA resistance is improved, but encryption process complexity increases

Engineering Contradiction:

ImproveCPA resistanceVSAvoidencryption process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent makes the mask generation function universal by designing it to handle multiple purposes: generating masks for encryption, ensuring semantic security, and maintaining compatibility with existing encryption APIs. The MGF serves multiple functions within a single component, which improves CPA resistance without proportionally increasing the overall system complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the mask generation functionality with the existing encryption API structure. By integrating the MGF into the encryption process flow rather than adding it as a separate external component, the system achieves CPA resistance while minimizing the increase in process complexity. The MGF and encryption function are combined in a coordinated manner that maintains operational simplicity.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS12355858B2Method and apparatus for encrypting and decrypting and reading and writing messages, computer device, and storage medium

Publication Date: 2025.07.08 BIGO TECH PTE LTD

AI summary

A method for encrypting messages is provided. The method for encrypting messages includes: generating a seed; generating a mask based on the seed; generating a masked message by masking an original message using the mask; acquiring a target message by performing white box encryption on the masked message; and disclosing the target message and the seed.