go-ethereum/crypto/bls12381/fp12.go
2024-04-08 16:10:46 +02:00

303 lines
6.6 KiB
Go

package bls12381
import (
"errors"
"math/big"
)
type fp12 struct {
fp12temp
fp6 *fp6
}
type fp12temp struct {
t2 [7]*fe2
t6 [4]*fe6
wt2 [3]*wfe2
wt6 [3]*wfe6
}
func newFp12Temp() fp12temp {
t2 := [7]*fe2{}
t6 := [4]*fe6{}
for i := 0; i < len(t2); i++ {
t2[i] = &fe2{}
}
for i := 0; i < len(t6); i++ {
t6[i] = &fe6{}
}
wt2 := [3]*wfe2{}
for i := 0; i < len(wt2); i++ {
wt2[i] = &wfe2{}
}
wt6 := [3]*wfe6{}
for i := 0; i < len(wt6); i++ {
wt6[i] = &wfe6{}
}
return fp12temp{t2, t6, wt2, wt6}
}
func newFp12(fp6 *fp6) *fp12 {
t := newFp12Temp()
if fp6 == nil {
return &fp12{t, newFp6(nil)}
}
return &fp12{t, fp6}
}
func (e *fp12) fp2() *fp2 {
return e.fp6.fp2
}
func (e *fp12) fromBytes(in []byte) (*fe12, error) {
if len(in) != 576 {
return nil, errors.New("input string length must be equal to 576 bytes")
}
fp6 := e.fp6
c1, err := fp6.fromBytes(in[:6*fpByteSize])
if err != nil {
return nil, err
}
c0, err := fp6.fromBytes(in[6*fpByteSize:])
if err != nil {
return nil, err
}
return &fe12{*c0, *c1}, nil
}
func (e *fp12) toBytes(a *fe12) []byte {
fp6 := e.fp6
out := make([]byte, 12*fpByteSize)
copy(out[:6*fpByteSize], fp6.toBytes(&a[1]))
copy(out[6*fpByteSize:], fp6.toBytes(&a[0]))
return out
}
func (e *fp12) new() *fe12 {
return new(fe12)
}
func (e *fp12) zero() *fe12 {
return new(fe12)
}
func (e *fp12) one() *fe12 {
return new(fe12).one()
}
func fp12Add(c, a, b *fe12) {
fp6Add(&c[0], &a[0], &b[0])
fp6Add(&c[1], &a[1], &b[1])
}
func fp12Double(c, a *fe12) {
fp6Double(&c[0], &a[0])
fp6Double(&c[1], &a[1])
}
func fp12Sub(c, a, b *fe12) {
fp6Sub(&c[0], &a[0], &b[0])
fp6Sub(&c[1], &a[1], &b[1])
}
func fp12Neg(c, a *fe12) {
fp6Neg(&c[0], &a[0])
fp6Neg(&c[1], &a[1])
}
func fp12Conjugate(c, a *fe12) {
c[0].set(&a[0])
fp6Neg(&c[1], &a[1])
}
func (e *fp12) mul(c, a, b *fe12) {
wt, t := e.wt6, e.t6
e.fp6.wmul(wt[1], &a[0], &b[0])
e.fp6.wmul(wt[2], &a[1], &b[1])
fp6Add(t[0], &a[0], &a[1])
fp6Add(t[3], &b[0], &b[1])
e.fp6.wmul(wt[0], t[0], t[3])
wfp6SubAssign(wt[0], wt[1])
wfp6SubAssign(wt[0], wt[2])
c[1].fromWide(wt[0])
e.fp6.wmulByNonResidueAssign(wt[2])
wfp6AddAssign(wt[1], wt[2])
c[0].fromWide(wt[1])
}
func (e *fp12) mulAssign(a, b *fe12) {
wt, t := e.wt6, e.t6
e.fp6.wmul(wt[1], &a[0], &b[0])
e.fp6.wmul(wt[2], &a[1], &b[1])
fp6Add(t[0], &a[0], &a[1])
fp6Add(t[3], &b[0], &b[1])
e.fp6.wmul(wt[0], t[0], t[3])
wfp6SubAssign(wt[0], wt[1])
wfp6SubAssign(wt[0], wt[2])
a[1].fromWide(wt[0])
e.fp6.wmulByNonResidueAssign(wt[2])
wfp6AddAssign(wt[1], wt[2])
a[0].fromWide(wt[1])
}
func (e *fp12) mul014(a *fe12, b0, b1, b4 *fe2) {
wt, t := e.wt6, e.t6
e.fp6.wmul01(wt[0], &a[0], b0, b1)
e.fp6.wmul1(wt[1], &a[1], b4)
fp2LaddAssign(b1, b4)
fp6Ladd(t[2], &a[1], &a[0])
e.fp6.wmul01(wt[2], t[2], b0, b1)
wfp6SubAssign(wt[2], wt[0])
wfp6SubAssign(wt[2], wt[1])
a[1].fromWide(wt[2])
e.fp6.wmulByNonResidueAssign(wt[1])
wfp6AddAssign(wt[0], wt[1])
a[0].fromWide(wt[0])
}
func (e *fp12) square(c, a *fe12) {
t := e.t6
// Multiplication and Squaring on Pairing-Friendly Fields
// Complex squaring algorithm
// https://eprint.iacr.org/2006/471
fp6Add(t[0], &a[0], &a[1])
e.fp6.mul(t[2], &a[0], &a[1])
e.fp6.mulByNonResidue(t[1], &a[1])
fp6AddAssign(t[1], &a[0])
e.fp6.mulByNonResidue(t[3], t[2])
e.fp6.mul(t[0], t[0], t[1])
fp6SubAssign(t[0], t[2])
fp6Sub(&c[0], t[0], t[3])
fp6Double(&c[1], t[2])
}
func (e *fp12) squareAssign(a *fe12) {
t := e.t6
// Multiplication and Squaring on Pairing-Friendly Fields
// Complex squaring algorithm
// https://eprint.iacr.org/2006/471
fp6Add(t[0], &a[0], &a[1])
e.fp6.mul(t[2], &a[0], &a[1])
e.fp6.mulByNonResidue(t[1], &a[1])
fp6AddAssign(t[1], &a[0])
e.fp6.mulByNonResidue(t[3], t[2])
e.fp6.mul(t[0], t[0], t[1])
fp6SubAssign(t[0], t[2])
fp6Sub(&a[0], t[0], t[3])
fp6Double(&a[1], t[2])
}
func (e *fp12) inverse(c, a *fe12) {
// Guide to Pairing Based Cryptography
// Algorithm 5.16
t := e.t6
e.fp6.square(t[0], &a[0]) // a0^2
e.fp6.square(t[1], &a[1]) // a1^2
e.fp6.mulByNonResidue(t[1], t[1]) // βa1^2
fp6SubAssign(t[0], t[1]) // v = (a0^2 - a1^2)
e.fp6.inverse(t[1], t[0]) // v = v^-1
e.fp6.mul(&c[0], &a[0], t[1]) // c0 = a0v
e.fp6.mulAssign(t[1], &a[1]) //
fp6Neg(&c[1], t[1]) // c1 = -a1v
}
func (e *fp12) exp(c, a *fe12, s *big.Int) {
z := e.one()
for i := s.BitLen() - 1; i >= 0; i-- {
e.square(z, z)
if s.Bit(i) == 1 {
e.mul(z, z, a)
}
}
c.set(z)
}
func (e *fp12) cyclotomicExp(c, a *fe12, s *big.Int) {
z := e.one()
for i := s.BitLen() - 1; i >= 0; i-- {
e.cyclotomicSquare(z)
if s.Bit(i) == 1 {
e.mul(z, z, a)
}
}
c.set(z)
}
func (e *fp12) cyclotomicSquare(a *fe12) {
t := e.t2
// Guide to Pairing Based Cryptography
// 5.5.4 Airthmetic in Cyclotomic Groups
e.fp4Square(t[3], t[4], &a[0][0], &a[1][1])
fp2Sub(t[2], t[3], &a[0][0])
fp2DoubleAssign(t[2])
fp2Add(&a[0][0], t[2], t[3])
fp2Add(t[2], t[4], &a[1][1])
fp2DoubleAssign(t[2])
fp2Add(&a[1][1], t[2], t[4])
e.fp4Square(t[3], t[4], &a[1][0], &a[0][2])
e.fp4Square(t[5], t[6], &a[0][1], &a[1][2])
fp2Sub(t[2], t[3], &a[0][1])
fp2DoubleAssign(t[2])
fp2Add(&a[0][1], t[2], t[3])
fp2Add(t[2], t[4], &a[1][2])
fp2DoubleAssign(t[2])
fp2Add(&a[1][2], t[2], t[4])
mulByNonResidue(t[3], t[6])
fp2Add(t[2], t[3], &a[1][0])
fp2DoubleAssign(t[2])
fp2Add(&a[1][0], t[2], t[3])
fp2Sub(t[2], t[5], &a[0][2])
fp2DoubleAssign(t[2])
fp2Add(&a[0][2], t[2], t[5])
}
func (e *fp12) fp4Square(c0, c1, a0, a1 *fe2) {
wt, t := e.wt2, e.t2
// Multiplication and Squaring on Pairing-Friendly Fields
// Karatsuba squaring algorithm
// https://eprint.iacr.org/2006/471
wfp2Square(wt[0], a0)
wfp2Square(wt[1], a1)
wfp2MulByNonResidue(wt[2], wt[1])
wfp2AddAssign(wt[2], wt[0])
c0.fromWide(wt[2])
fp2Add(t[0], a0, a1)
wfp2Square(wt[2], t[0])
wfp2SubAssign(wt[2], wt[0])
wfp2SubAssign(wt[2], wt[1])
c1.fromWide(wt[2])
}
func (e *fp12) frobeniusMap1(a *fe12) {
fp6, fp2 := e.fp6, e.fp6.fp2
fp6.frobeniusMap1(&a[0])
fp6.frobeniusMap1(&a[1])
fp2.mulAssign(&a[1][0], &frobeniusCoeffs12[1])
fp2.mulAssign(&a[1][1], &frobeniusCoeffs12[1])
fp2.mulAssign(&a[1][2], &frobeniusCoeffs12[1])
}
func (e *fp12) frobeniusMap2(a *fe12) {
fp6, fp2 := e.fp6, e.fp6.fp2
fp6.frobeniusMap2(&a[0])
fp6.frobeniusMap2(&a[1])
fp2.mulAssign(&a[1][0], &frobeniusCoeffs12[2])
fp2.mulAssign(&a[1][1], &frobeniusCoeffs12[2])
fp2.mulAssign(&a[1][2], &frobeniusCoeffs12[2])
}
func (e *fp12) frobeniusMap3(a *fe12) {
fp6, fp2 := e.fp6, e.fp6.fp2
fp6.frobeniusMap3(&a[0])
fp6.frobeniusMap3(&a[1])
fp2.mulAssign(&a[1][0], &frobeniusCoeffs12[3])
fp2.mulAssign(&a[1][1], &frobeniusCoeffs12[3])
fp2.mulAssign(&a[1][2], &frobeniusCoeffs12[3])
}