/* GLV method */
public static BIG[] glv(BIG e)
{
int i, j;
BIG t = new BIG(0);
BIG q = new BIG(ROM.CURVE_Order);
BIG[] u = new BIG[2];
BIG[] v = new BIG[2];
for (i = 0; i < 2; i++)
{
t.copy(new BIG(ROM.CURVE_W[i])); // why not just t=new BIG(ROM.CURVE_W[i]);
DBIG d = BIG.mul(t, e);
v[i] = new BIG(d.div(q));
u[i] = new BIG(0);
}
u[0].copy(e);
for (i = 0; i < 2; i++)
{
for (j = 0; j < 2; j++)
{
t.copy(new BIG(ROM.CURVE_SB[j][i]));
t.copy(BIG.modmul(v[j], t, q));
u[i].add(q);
u[i].sub(t);
u[i].mod(q);
}
}
return(u);
}
/* Galbraith & Scott Method */
public static BIG[] gs(BIG e)
{
int i, j;
BIG t = new BIG(0);
BIG q = new BIG(ROM.CURVE_Order);
BIG[] u = new BIG[4];
BIG[] v = new BIG[4];
for (i = 0; i < 4; i++)
{
t.copy(new BIG(ROM.CURVE_WB[i]));
DBIG d = BIG.mul(t, e);
v[i] = new BIG(d.div(q));
u[i] = new BIG(0);
}
u[0].copy(e);
for (i = 0; i < 4; i++)
{
for (j = 0; j < 4; j++)
{
t.copy(new BIG(ROM.CURVE_BB[j][i]));
t.copy(BIG.modmul(v[j], t, q));
u[i].add(q);
u[i].sub(t);
u[i].mod(q);
}
}
return(u);
}
/* this*=b mod Modulus */
public void mul(FP b)
{
long ea = BIG.EXCESS(x);
long eb = BIG.EXCESS(b.x);
if ((ea + 1) * (eb + 1) + 1 >= ROM.FEXCESS)
{
reduce();
}
DBIG d = BIG.mul(x, b.x);
x.copy(BIG.mod(d));
}
/* z=x*y, t is workspace */
private void karmul(int vp, FF x, int xp, FF y, int yp, FF t, int tp, int n)
{
int nd2;
if (n == 1)
{
DBIG d = BIG.mul(x.v[xp], y.v[yp]);
v[vp + 1] = d.Split(8 * ROM.MODBYTES);
v[vp].copy(d);
return;
}
nd2 = n / 2;
radd(vp, x, xp, x, xp + nd2, nd2);
//rnorm(vp,nd2);
radd(vp + nd2, y, yp, y, yp + nd2, nd2);
//rnorm(vp+nd2,nd2);
t.karmul(tp, this, vp, this, vp + nd2, t, tp + n, nd2);
karmul(vp, x, xp, y, yp, t, tp + n, nd2);
karmul(vp + n, x, xp + nd2, y, yp + nd2, t, tp + n, nd2);
t.rdec(tp, this, vp, n);
t.rdec(tp, this, vp + n, n);
rinc(vp + nd2, t, tp, n);
rnorm(vp, 2 * n);
}
