bn_utils.go

package otr3

import (
	"math/big"

	"github.com/coyim/constbn"
)

func modExp(g, x, m *big.Int) *big.Int {
	return new(big.Int).Exp(g, x, m)
}

func modExpP(g, x *big.Int) *big.Int {
	return modExp(g, x, p)
}

func modExpCT(g *constbn.Int, x secretKeyValue, m *constbn.Int) *constbn.Int {
	return new(constbn.Int).ExpB(g, []byte(x), m)
}

func modExpPCT(g *constbn.Int, x secretKeyValue) *constbn.Int {
	return modExpCT(g, x, pct)
}

func modInverse(g, x *big.Int) *big.Int {
	return new(big.Int).ModInverse(g, x)
}

func mul(l, r *big.Int) *big.Int {
	return new(big.Int).Mul(l, r)
}

func sub(l, r *big.Int) *big.Int {
	return new(big.Int).Sub(l, r)
}

func mulMod(l, r, m *big.Int) *big.Int {
	res := mul(l, r)
	res.Mod(res, m)
	return res
}

// Fast division over a modular field, without using division
func divMod(l, r, m *big.Int) *big.Int {
	return mulMod(l, modInverse(r, m), m)
}

func subMod(l, r, m *big.Int) *big.Int {
	res := sub(l, r)
	res.Mod(res, m)
	return res
}

func mod(l, m *big.Int) *big.Int {
	return new(big.Int).Mod(l, m)
}

func lt(l, r *big.Int) bool {
	return l.Cmp(r) == -1
}

func lte(l, r *big.Int) bool {
	return l.Cmp(r) != 1
}

func eq(l, r *big.Int) bool {
	return l.Cmp(r) == 0
}

func gt(l, r *big.Int) bool {
	return l.Cmp(r) == 1
}

func gte(l, r *big.Int) bool {
	return l.Cmp(r) != -1
}