Block Cipher PRF Construction for Variable-Length Secure Output
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Solution Overview
Problem
Existing pseudo-random functions (PRFs) face challenges in generating variable output lengths efficiently and with high security, particularly when based on block ciphers, leading to inefficiencies and reduced security.
Innovation Solution
A block cipher-based method that generates variable-output-length pseudo-random numbers by producing intermediate values, performing block cipher-based encoding, and deriving a final value through combinations, using hash functions for length pre-processing to ensure high security and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a hash function-based pseudo-random function is used, then variable output length is supported, but efficiency is reduced compared to block ciphers
Solution Approach 1:
The input is divided into multiple blocks of fixed size, and each block is processed independently through the block cipher. This segmentation allows the system to handle variable-length inputs efficiently by processing them in manageable chunks, achieving both variable output length and high efficiency.
Solution Approach 2:
The block cipher-based PRF construction provides universal functionality by accepting variable-length inputs and producing variable-length outputs while maintaining the efficiency characteristics of block ciphers. The construction works for any output length requirement, making it multi-functional and adaptable.
2Productivity
If an n-bit block cipher is used for PRF, then efficiency is maintained, but security is limited to n/2 bits
Solution Approach 1:
Multiple block cipher operations are combined through a specific construction that processes multiple input blocks and combines their outputs. This merging of operations increases the effective security level beyond the single-block cipher limit while maintaining efficiency, achieving n-bit security rather than n/2 bits.
Solution Approach 2:
The construction performs preliminary processing by dividing the input into blocks and preparing multiple intermediate values before final output generation. This preliminary action allows the system to leverage multiple block cipher instances in a way that boosts security without proportionally increasing computational cost.
3Reliability
If Double-block-Hash-then-Sum style PRFs are used to improve security, then security level increases, but efficiency decreases and applicability is limited due to fixed input or output length
Solution Approach 1:
The construction dynamically adapts to different input and output length requirements while maintaining high security. Unlike fixed-length constructions, this system can handle variable-length inputs and produce variable-length outputs, making it dynamically applicable to various cryptographic scenarios without sacrificing efficiency or security.
Data Source
AI summary
The present disclosure relates to a block cipher-based variable-output-length pseudo-random number generation method, apparatus, system, and computer program, and more specifically, in the present disclosure, a method for generating a variable-output-length pseudo-random number using a computing device may include the steps of: generating a plurality of intermediate values, based on a given input value; producing a plurality of intermediate random values by performing block cipher-based encoding on the plurality of intermediate values; and deriving a final random value for the input value, based on a combination of the plurality of intermediate random values.