code: public static ECPoint publicPointFromPrivate(BigInteger privKey) {
          /*
           * TODO: FixedPointCombMultiplier currently doesn't support scalars longer than the group order,
           * but that could change in future versions.
           */
          if (privKey.bitLength() > CURVE.getN().bitLength()) {
              privKey = privKey.mod(CURVE.getN());
          }
          return new FixedPointCombMultiplier().multiply(CURVE.getG(), privKey);
      }
docs: Returns public key point from the given private key. To convert a byte array into a BigInteger,
  use {@code new BigInteger(1, bytes);}