/* Pollards kangaroos used to return PIN error */
public static int KANGAROO(sbyte[] E, sbyte[] F)
{
FP12 ge = FP12.fromBytes(E);
FP12 gf = FP12.fromBytes(F);
int[] distance = new int[TS];
FP12 t = new FP12(gf);
FP12[] table = new FP12[TS];
int i, j, m, s, dn, dm, res, steps;
s = 1;
for (m = 0; m < TS; m++)
{
distance[m] = s;
table[m] = new FP12(t);
s *= 2;
t.usqr();
}
t.one();
dn = 0;
for (j = 0; j < TRAP; j++)
{
i = t.geta().geta().A.lastbits(8) % TS;
t.mul(table[i]);
dn += distance[i];
}
gf.copy(t);
gf.conj();
steps = 0;
dm = 0;
res = 0;
while (dm - dn < MAXPIN)
{
steps++;
if (steps > 4 * TRAP)
{
break;
}
i = ge.geta().geta().A.lastbits(8) % TS;
ge.mul(table[i]);
dm += distance[i];
if (ge.Equals(t))
{
res = dm - dn;
break;
}
if (ge.Equals(gf))
{
res = dn - dm;
break;
}
}
if (steps > 4 * TRAP || dm - dn >= MAXPIN)
{
res = 0;
} // Trap Failed - probable invalid token
return(res);
}