/* r=x^n using XTR method on traces of FP12s */
public FP4 Xtr_Pow(BIG n)
{
FP4 a = new FP4(3);
FP4 b = new FP4(this);
FP4 c = new FP4(b);
c.Xtr_D();
FP4 t = new FP4(0);
FP4 r = new FP4(0);
n.Norm();
int par = n.Parity();
BIG v = new BIG(n);
v.FShr(1);
if (par == 0)
{
v.Dec(1);
v.Norm();
}
int nb = v.NBits();
for (int i = nb - 1; i >= 0; i--)
{
if (v.Bit(i) != 1)
{
t.Copy(b);
Conj();
c.Conj();
b.Xtr_A(a, this, c);
Conj();
c.Copy(t);
c.Xtr_D();
a.Xtr_D();
}
else
{
t.Copy(a);
t.Conj();
a.Copy(b);
a.Xtr_D();
b.Xtr_A(c, this, t);
c.Xtr_D();
}
}
if (par == 0)
{
r.Copy(c);
}
else
{
r.Copy(b);
}
r.Reduce();
return(r);
}
/* this=this^e */
/* Note this is simple square and multiply, so not side-channel safe */
public FP12 Pow(BIG e)
{
Norm();
e.Norm();
BIG e3 = new BIG(e);
e3.PMul(3);
e3.Norm();
FP12 w = new FP12(this);
int nb = e3.NBits();
for (int i = nb - 2; i >= 1; i--)
{
w.USqr();
int bt = e3.Bit(i) - e.Bit(i);
if (bt == 1)
{
w.mul(this);
}
if (bt == -1)
{
Conj();
w.mul(this);
Conj();
}
}
w.Reduce();
return(w);
/*
* BIG z=new BIG(e);
* FP12 r=new FP12(1);
*
* while (true)
* {
* int bt=z.parity();
* z.fshr(1);
* if (bt==1) r.mul(w);
* if (z.iszilch()) break;
* w.usqr();
* }
* r.reduce();
* return r; */
}
/* 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);
}
