Pre-computation Table for Discrete Logarithm Computation

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Solution Overview

Problem

Current public key encryption systems face inefficiencies in solving the discrete logarithm problem, which is crucial for generating secret keys, due to the computational difficulty of finding discrete logarithms in finite fields.

Innovation Solution

The method involves generating a pre-computation table using initial values and an iterating function to store chains of function values, allowing for efficient computation of discrete logarithms by matching target elements with stored values, reducing the time required to solve the problem.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If a pre-computation table is generated and stored, then the time to solve discrete logarithm problems is reduced, but the memory requirements increase

Engineering Contradiction:
Improvecomputation timeVSAvoidmemory space
Core Design Contradiction:
Loss of timeVSQuantity of substance

Solution Approach 1:

The patent applies preliminary action by pre-computing and storing chains of function values in a table before the actual discrete logarithm problem needs to be solved. The pre-computation table stores values of the form (g^i mod p, i) where g is a generator and i ranges from 0 to a predetermined maximum. When a discrete logarithm problem y = g^x mod p needs to be solved, the system only needs to compute g^y mod p and look up the result in the pre-computed table, significantly reducing computation time at the cost of storing the pre-computed values in memory.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If the pre-computation table stores more function values, then the accuracy and completeness of discrete logarithm solutions improve, but the device complexity increases

Engineering Contradiction:
Improvesolution accuracyVSAvoidtable structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the pre-computation table into multiple segments or chains, where each chain corresponds to a different starting value or generator. Instead of storing all possible discrete logarithm values in a single large table, the system creates multiple smaller chains that can be independently managed and searched. This segmentation reduces the complexity of individual table structures while maintaining comprehensive coverage for solving discrete logarithm problems.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentUS9077536B2Method and apparatus for solving discrete logarithm problem using pre-computation table
Publication Date: 2015.07.07 SEOUL NATIONAL UNIVERSITY R&DB FOUNDATION
  • US9077536B2 patent drawing
  • US9077536B2 patent drawing
  • US9077536B2 patent drawing

AI summary

A method and apparatus for computing a discrete logarithm using a pre-computation table are provided. The method includes previously generating the pre-computation table consisting of chains of function values obtained by applying an iterating function to a predetermined number of initial values having a generator of the cyclic group as a base and having different exponents; and if a function value obtained by applying the iterating function to a value having a target element as a base and having an exponent is identical to a function value stored in the pre-computation table, computing the discrete logarithm of the target element by using exponent information of the two function values.