/* Extract PIN from TOKEN for identity CID */
public static int EXTRACT_PIN(sbyte[] CID, int pin, sbyte[] TOKEN)
{
ECP P = ECP.fromBytes(TOKEN);
if (P.is_infinity())
{
return(INVALID_POINT);
}
sbyte[] h = hashit(0, CID);
ECP R = mapit(h);
pin %= MAXPIN;
R = R.pinmul(pin, PBLEN);
P.sub(R);
P.toBytes(TOKEN);
return(0);
}