ceremonyclient/nekryptology/pkg/sharing/v1/polynomial.go
2023-07-05 00:32:28 -05:00

50 lines
1.1 KiB
Go

//
// Copyright Coinbase, Inc. All Rights Reserved.
//
// SPDX-License-Identifier: Apache-2.0
//
package v1
import (
"source.quilibrium.com/quilibrium/monorepo/nekryptology/pkg/core/curves"
)
type polynomial struct {
Coefficients []*curves.Element
}
// newPoly creates a random polynomial of the given degree but with the provided intercept value
func newPoly(intercept *curves.Element, degree uint32) (polynomial, error) {
p := polynomial{
Coefficients: make([]*curves.Element, degree),
}
// Intercept is the value to be split
p.Coefficients[0] = intercept
// random coefficients
for i := uint32(1); i < degree; i++ {
c, err := intercept.Field().RandomElement(nil)
if err != nil {
return p, err
}
p.Coefficients[i] = c
}
return p, nil
}
// evaluate returns the value of the polynomial for the given x
func (p polynomial) evaluate(x *curves.Element) *curves.Element {
// Compute the polynomial value using Horner's Method
degree := len(p.Coefficients) - 1
result := p.Coefficients[degree].Clone()
for i := degree - 1; i >= 0; i-- {
result = result.Mul(x).Add(p.Coefficients[i])
}
return result
}