White-Box Encryption Key Generation Without Random Numbers
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Solution Overview
Problem
Existing white-box cryptography techniques face security challenges, including the need for external encoding that alters the encryption algorithm, vulnerability to key recovery, and difficulty in maintaining strong security without random numbers, especially in environments where attackers can control random number sources.
Innovation Solution
A block cipher system that generates a cryptographic key securely in the white-box model without using random numbers, ensuring strong security by implementing the block cipher as a table-based system with unpredictable key generation, maintaining indistinguishability and preventing key recovery attacks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external encoding is added to enhance security in white-box model, then security is improved, but the encryption algorithm becomes different from the original and device complexity increases
Solution Approach 1:
The patent extracts the key generation function from the traditional encryption algorithm and implements it as a separate white-box secure function. This allows the main encryption algorithm to remain unchanged while adding security through a dedicated key generation mechanism that operates independently, thus avoiding the complexity of modifying the entire encryption algorithm.
Solution Approach 2:
The patent introduces a white-box secure key generation function as an intermediary between the key input and the encryption process. This intermediary function securely generates keys without requiring external encoding or modifying the original encryption algorithm, thereby enhancing security while maintaining algorithmic simplicity.
2Reliability
If random numbers are used to guarantee security in white-box model, then security is improved, but the attacker can freely control the random number source
Solution Approach 1:
The patent implements a self-service key generation mechanism where the white-box secure key generation function internally generates keys without requiring external random numbers. The function uses its own internal state and the input key material to produce secure keys, eliminating dependence on external random number sources that could be controlled by attackers.
Solution Approach 2:
The patent extracts the randomness requirement from the key generation process and replaces it with an internal state-based mechanism. By removing the need for external random numbers, the system eliminates the vulnerability to attacker control while maintaining security through the white-box protected key generation function.
3Reliability
If table-based implementation is used for white-box security, then key recovery resistance is improved, but the table size and memory requirements increase
Solution Approach 1:
The patent segments the key generation process into multiple functional components within the white-box secure function. Instead of using a single large lookup table, the system divides the key generation into smaller operations that use smaller tables, reducing overall memory requirements while maintaining security through the segmented white-box implementation.
Data Source
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AI summary
[Problem] To ensure strong security without using a random number in a white-box model. [Solution] An encryption device according to the present disclosure includes: an encryption part configured to encrypt an input value using a black-box model in which input/output values are able to be recognized from the outside and an intermediate value is not able to be recognized from the outside; and a key generation part configured to encrypt the input value to the encryption part to generate a cryptographic key of the encryption part using a white-box model in which the input/output value and the intermediate value are able to be recognized from the outside.