code: protected BigInteger RSAVP1(RSAPublicKey key, BigInteger s) {
  
          if (key == null) {
              throw new IllegalArgumentException("key");
          }
  
          if (s == null) {
              throw new IllegalArgumentException("s");
          }
          BigInteger n = key.getModulus();
          BigInteger e = key.getPublicExponent();
  
          if (s.compareTo(BigInteger.ONE) == -1 || s.compareTo(n) != -1) {
              throw new IllegalArgumentException("message representative out of range");
          }
  
          return s.modPow(e, n);
      }
docs: /*
  See https://tools.ietf.org/html/rfc3447#section-5.2.2