/* Multiply P by e in group G2 */
public static ECP2 G2Mul(ECP2 P, BIG e)
{
ECP2 R;
if (USE_GS_G2)
{
ECP2[] Q = new ECP2[4];
FP2 f = new FP2(new BIG(ROM.Fra), new BIG(ROM.Frb));
if (ECP.SEXTIC_TWIST == ECP.M_TYPE)
{
f.Inverse();
f.Norm();
}
BIG q = new BIG(ROM.CURVE_Order);
BIG[] u = GS(e);
BIG t = new BIG(0);
int i, np, nn;
//P.affine();
Q[0] = new ECP2();
Q[0].Copy(P);
for (i = 1; i < 4; i++)
{
Q[i] = new ECP2();
Q[i].Copy(Q[i - 1]);
Q[i].Frob(f);
}
for (i = 0; i < 4; i++)
{
np = u[i].NBits();
t.Copy(BIG.ModNeg(u[i], q));
nn = t.NBits();
if (nn < np)
{
u[i].Copy(t);
Q[i].Neg();
}
u[i].Norm();
//Q[i].affine();
}
R = ECP2.Mul4(Q, u);
}
else
{
R = P.Mul(e);
}
return(R);
}
/* this=1/this */
public void Inverse()
{
// norm();
FP2 t1 = new FP2(a);
FP2 t2 = new FP2(b);
t1.Sqr();
t2.Sqr();
t2.Mul_Ip();
t2.Norm();
t1.Sub(t2);
t1.Inverse();
a.Mul(t1);
t1.Neg();
t1.Norm();
b.Mul(t1);
}
/* sqrt(a+ib) = sqrt(a+sqrt(a*a-n*b*b)/2)+ib/(2*sqrt(a+sqrt(a*a-n*b*b)/2)) */
/* returns true if this is QR */
public bool Sqrt()
{
if (IsZilch())
{
return(true);
}
FP2 wa = new FP2(a);
FP2 ws = new FP2(b);
FP2 wt = new FP2(a);
if (ws.IsZilch())
{
if (wt.Sqrt())
{
a.Copy(wt);
b.Zero();
}
else
{
wt.Div_Ip();
wt.Sqrt();
b.Copy(wt);
a.Zero();
}
return(true);
}
ws.Sqr();
wa.Sqr();
ws.Mul_Ip();
ws.Norm();
wa.Sub(ws);
ws.Copy(wa);
if (!ws.Sqrt())
{
return(false);
}
wa.Copy(wt);
wa.Add(ws);
wa.Norm();
wa.Div2();
if (!wa.Sqrt())
{
wa.Copy(wt);
wa.Sub(ws);
wa.Norm();
wa.Div2();
if (!wa.Sqrt())
{
return(false);
}
}
wt.Copy(b);
ws.Copy(wa);
ws.Add(wa);
ws.Inverse();
wt.Mul(ws);
a.Copy(wa);
b.Copy(wt);
return(true);
}
/* Optimal R-ate double pairing e(P,Q).e(R,S) */
public static FP12 Ate2(ECP2 P1, ECP Q1, ECP2 R1, ECP S1)
{
FP2 f;
BIG x = new BIG(ROM.CURVE_Bnx);
BIG n = new BIG(x);
ECP2 K = new ECP2();
FP12 lv;
int bt;
ECP2 P = new ECP2(P1);
ECP Q = new ECP(Q1);
P.Affine();
Q.Affine();
ECP2 R = new ECP2(R1);
ECP S = new ECP(S1);
R.Affine();
S.Affine();
if (ECP.CURVE_PAIRING_TYPE == ECP.BN)
{
f = new FP2(new BIG(ROM.Fra), new BIG(ROM.Frb));
if (ECP.SEXTIC_TWIST == ECP.M_TYPE)
{
f.Inverse();
f.Norm();
}
n.PMul(6);
if (ECP.SIGN_OF_X == ECP.POSITIVEX)
{
n.Inc(2);
}
else
{
n.Dec(2);
}
}
else
{
n.Copy(x);
}
n.Norm();
BIG n3 = new BIG(n);
n3.PMul(3);
n3.Norm();
FP Qx = new FP(Q.GetX());
FP Qy = new FP(Q.GetY());
FP Sx = new FP(S.GetX());
FP Sy = new FP(S.GetY());
ECP2 A = new ECP2();
ECP2 B = new ECP2();
FP12 r = new FP12(1);
A.Copy(P);
B.Copy(R);
ECP2 MP = new ECP2();
MP.Copy(P);
MP.Neg();
ECP2 MR = new ECP2();
MR.Copy(R);
MR.Neg();
int nb = n3.NBits();
for (int i = nb - 2; i >= 1; i--)
{
r.Sqr();
lv = Line(A, A, Qx, Qy);
r.SMul(lv, ECP.SEXTIC_TWIST);
lv = Line(B, B, Sx, Sy);
r.SMul(lv, ECP.SEXTIC_TWIST);
bt = n3.Bit(i) - n.Bit(i); // bt=n.bit(i);
if (bt == 1)
{
lv = Line(A, P, Qx, Qy);
r.SMul(lv, ECP.SEXTIC_TWIST);
lv = Line(B, R, Sx, Sy);
r.SMul(lv, ECP.SEXTIC_TWIST);
}
if (bt == -1)
{
//P.neg();
lv = Line(A, MP, Qx, Qy);
r.SMul(lv, ECP.SEXTIC_TWIST);
//P.neg();
//R.neg();
lv = Line(B, MR, Sx, Sy);
r.SMul(lv, ECP.SEXTIC_TWIST);
//R.neg();
}
}
if (ECP.SIGN_OF_X == ECP.NEGATIVEX)
{
r.Conj();
}
/* R-ate fixup required for BN curves */
if (ECP.CURVE_PAIRING_TYPE == ECP.BN)
{
if (ECP.SIGN_OF_X == ECP.NEGATIVEX)
{
// r.conj();
A.Neg();
B.Neg();
}
K.Copy(P);
K.Frob(f);
lv = Line(A, K, Qx, Qy);
r.SMul(lv, ECP.SEXTIC_TWIST);
K.Frob(f);
K.Neg();
lv = Line(A, K, Qx, Qy);
r.SMul(lv, ECP.SEXTIC_TWIST);
K.Copy(R);
K.Frob(f);
lv = Line(B, K, Sx, Sy);
r.SMul(lv, ECP.SEXTIC_TWIST);
K.Frob(f);
K.Neg();
lv = Line(B, K, Sx, Sy);
r.SMul(lv, ECP.SEXTIC_TWIST);
}
return(r);
}
