Final Exponentiation Calculation Device for BLS Curves

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Solution Overview

Problem

The calculation of final exponentiation in pairing operations on BLS curves with embedding degrees other than those previously studied is inefficient, with no known method to speed up the process effectively.

Innovation Solution

A device that decomposes the exponent part into an easy and hard part using a cyclotomic polynomial and transforms the hard part into a linear sum of the polynomial q(u), facilitating efficient calculation of the final exponentiation in pairing operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the final exponentiation is calculated using conventional methods on BLS curves with new embedding degrees, then the pairing operation can be performed, but the computational burden is extremely heavy and the calculation speed is slow

Engineering Contradiction:
Improvecalculation speed of final exponentiationVSAvoidtime required for final exponentiation calculation
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The patent applies segmentation by dividing the final exponentiation calculation into distinct phases: pre-computation of auxiliary values (including cyclotomic polynomial evaluation and intermediate exponentiations) and main computation phase. This segmentation allows the computationally intensive parts to be prepared in advance and reused, significantly reducing the time required during actual pairing operations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements preliminary action through extensive pre-computation of auxiliary values including evaluating cyclotomic polynomials, computing intermediate exponentiations, and preparing transformation matrices before the actual pairing operation. These pre-computed values are stored and reused during the main computation, eliminating redundant calculations and accelerating the final exponentiation process.

Inventive Principle:
Principle #10Preliminary action

2Device complexity

If the exponent part is decomposed using cyclotomic polynomial and transformed into linear sum, then the computational burden is reduced, but the device complexity increases due to additional transformation steps

Engineering Contradiction:
Improvecomplexity of exponent decomposition and transformationVSAvoidefficiency of final exponentiation calculation
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The patent applies parameter changes by transforming the exponent representation from a standard form to a decomposition based on cyclotomic polynomials. This parameter transformation allows the exponent to be expressed as a sum of terms with specific algebraic structures, enabling more efficient computation through properties of finite fields and elliptic curves, despite requiring additional transformation steps.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS20220269486A1Final exponentiation calculation device, pairing operation device, cryptographic processing device, final exponentiation calculation method, and computer readable medium
Publication Date: 2022.08.25 MITSUBISHI ELECTRIC CORP
  • US20220269486A1 patent drawing
  • US20220269486A1 patent drawing
  • US20220269486A1 patent drawing

AI summary

In a final exponentiation calculation device, a decomposition unit (221) decomposes an exponent part into an easy part and a hard part, using a cyclotomic polynomial, in a final exponentiation calculation part of a pairing operation on an elliptic curve represented by a polynomial r(u), a polynomial q(u), a polynomial t(u), an embedding degree k, and a parameter u. A transformation unit (222) transforms the hard part obtained by decomposition by the decomposition unit (221) into a linear sum of the polynomial q(u). An exponentiation calculation unit (23) calculates the final exponentiation calculation part, using the easy part and the hard part transformed into the linear sum of the polynomial q(u).