Format Preserving Encryption for Long Strings
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Solution Overview
Problem
Current format-preserving encryption (FPE) methods, such as the FF1 algorithm, are inefficient for encrypting long character strings, as they require repeated invocations of the AES cipher and big number arithmetic operations, leading to slow performance.
Innovation Solution
The Just Encrypt 1 (JE1) system reduces the number of AES invocations per 128 bits of input to slightly more than 3 and uses hardware arithmetic operations during encryption and decryption, minimizing big number arithmetic to improve speed and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the FF1 algorithm is used for format-preserving encryption, then the ciphertext format is preserved and compatibility with legacy functions is maintained, but the encryption speed becomes prohibitively slow for long inputs
Solution Approach 1:
The patent segments the long input string into multiple 128-bit blocks, processing each block independently through the AES cipher. This reduces the computational burden compared to processing the entire long string through multiple sequential FF1 invocations, thereby improving encryption speed while maintaining format preservation for each segment
Solution Approach 2:
The patent changes the operational parameters by using hardware arithmetic operations instead of software-based big number arithmetic. This parameter change in the computational method significantly accelerates the encryption process for long strings while maintaining the format-preserving property through controlled modular arithmetic operations
2Reliability
If multiple invocations of AES cipher are used in FF1 algorithm, then format-preserving encryption is achieved, but the computational complexity and processing time increase significantly
Solution Approach 1:
The patent divides the encryption process into segments corresponding to 128-bit blocks, with each segment requiring only a limited number of AES invocations. This segmentation reduces the total computational complexity compared to applying multiple FF1 invocations across the entire long input, while maintaining security through systematic processing of all segments
Solution Approach 2:
The patent replaces software-based big number arithmetic operations with hardware arithmetic operations. This substitution reduces computational complexity by leveraging dedicated hardware circuits optimized for arithmetic operations, thereby decreasing processing time and computational burden while maintaining the cryptographic security requirements
Data Source
AI summary
A format-preserving Just Encrypt 1 (JE1) system and method provides significant performance advantages over known FPE methods for longer character strings due to the technical improvements.