Encryption Method Resisting Known-Plaintext Attacks
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Solution Overview
Problem
Existing encryption methods are vulnerable to known-plaintext attacks (KPA) and face challenges in maintaining a good coding rate and efficiency, especially when applied to streaming encryption, as they often require significant memory and computational resources.
Innovation Solution
A method that generates a random number sequence from a one-dimensional array and uses it to transform the plaintext through exclusive-OR operations, combining with conventional encryption methods to enhance security and coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the encryption key size is increased to improve security against known-plaintext attacks, then security is improved, but device complexity and computational complexity increase
Solution Approach 1:
The encryption process is divided into two distinct stages: a preprocessing stage that applies a pseudorandom permutation to the plaintext, and a subsequent encryption stage that applies a standard encryption algorithm. This segmentation allows each stage to have optimized complexity characteristics, with the preprocessing stage using a lightweight permutation network and the second stage using standardized algorithms.
Solution Approach 2:
The patent applies a preliminary preprocessing step before the main encryption operation. This preprocessing involves applying a pseudorandom permutation using a permutation table generated from secret information, which transforms the plaintext structure in advance to defeat known-plaintext attacks before the standard encryption is applied.
2Reliability
If preprocessing is applied to increase computational complexity for KPA, then security is improved, but memory space requirements increase significantly
Solution Approach 1:
The permutation table is generated locally at the encryption device using a deterministic algorithm based on secret information (key and initialization vector), rather than requiring the entire table to be stored in memory. This allows the system to use minimal memory while still achieving the security benefits of the preprocessing step.
Solution Approach 2:
The system generates its own permutation table on-demand using a pseudo-random number generator seeded with secret information, eliminating the need to pre-load or cache large tables in memory. The generator serves itself by creating the necessary cryptographic material during the encryption process.
3Ease of manufacture
If standard encryption specifications are followed, then compliance is maintained, but security against known-plaintext attacks is reduced
Solution Approach 1:
The patent merges a custom preprocessing step with standard encryption algorithms in a hybrid encryption system. The preprocessing layer provides KPA resistance through pseudorandom permutation, while the subsequent layer uses standardized encryption (such as AES) to maintain compliance with encryption specifications, achieving both security and compliance goals simultaneously.
Data Source
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AI summary
[Problem] To provide, combining a conventional encryption scheme, an encryption that is excellent in coding ratio, suitable for stream encryption and safe against known plain text attacks. [Solution] From a random number sequence array consisting of random number sequences having no mutual correlations and having different lengths, a random number sequence is selected by using, as an index, a random number that is independently generated by means of a physical random number or the like. A plain text to be encrypted is then obfuscated on the basis of the selected random number sequence, further concatenated to the random number and thereafter subjected to application of a conventional type of encryption algorithm.